subject:(Autoignition)

1. Borghesi, Giulio. Autoignition in turbulent two-phase flows.

Degree: PhD, 2013, University of Cambridge

URL: http://www.dspace.cam.ac.uk/handle/1810/244235https://www.repository.cam.ac.uk/bitstream/1810/244235/2/license.txt ; https://www.repository.cam.ac.uk/bitstream/1810/244235/5/thesis.pdf.txt ; https://www.repository.cam.ac.uk/bitstream/1810/244235/3/thesis.pdf.txt ; https://www.repository.cam.ac.uk/bitstream/1810/244235/6/thesis.pdf.jpg

► This dissertation deals with the numerical investigation of the physics of sprays autoigniting at diesel engine conditions using Direct Numerical Simulations (DNS), and with the… (more)

▼ This dissertation deals with the numerical investigation of the physics of sprays autoigniting at diesel engine conditions using Direct Numerical Simulations (DNS), and with the modelling of droplet related effects within the Conditional Moment Closure (CMC) method for turbulent non-premixed combustion. The dissertation can be split in four different sections, with the content of each being summarized below. The first part of the dissertation introduces the equations that govern the temporal and spatial evolution of a turbulent reacting flow, and provides an extensive review of the CMC method for both single and two-phase flows. The problem of modelling droplet related effects in the CMC transport equations is discussed in detail, and physically-sound models for the unclosed terms that appear in these equations and that are affected by the droplet presence are derived. The second part of the dissertation deals with the application of the CMC method to the numerical simulation of several n-heptane sprays igniting at conditions relevant to diesel engine combustion. Droplet-related terms in the CMC equations were closed with the models developed in the first part of the dissertation. For all conditions investigated, CMC could correctly capture the ignition, propagation and anchoring phases of the spray flame. Inclusion of droplet terms in the CMC equations had little influence on the numerical predictions, in line with the findings of other authors. The third part of the dissertation presents a DNS study on the autoignition of n-heptane sprays at high pressure / low temperature conditions. The analysis revealed that spray ignition occurs first in well-mixed locations with a specific value of the mixture fraction. Changes in the operating conditions (initial turbulence intensity of the background gas, global equivalence ratio in the spray region, initial droplet size distribution) affected spray ignition through changes in the mixture formation process. For each spray, a characteristic ignition delay time and a characteristic droplet evaporation time could be defined. The ratio between these time scales was suggested as a key parameter for controlling the ignition delay of the spray. The last part of the dissertation exploits the DNS simulations to perform an a priori analysis of the applicability of the CMC method to autoigniting sprays. The study revealed that standard models for the mixing quantities used in CMC provide poor approximations in two-phase flows, and are partially responsible for the poor prediction of the ignition delay time. It was also observed that first-order closure of the chemical source terms performs poorly during the onset of ignition, suggesting that second-order closures may be more appropriate for studying spray autoignition problems. The contribution of the work presented in this dissertation is to provides a detailed insight into the physics of spray autoignition at diesel engine conditions, to propose and derive original methods for incorporating droplet evaporation effects…

Subjects/Keywords: CFD; Diesel engine; DNS; Autoignition

6 more images…

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Borghesi, G. (2013). Autoignition in turbulent two-phase flows. (Doctoral Dissertation). University of Cambridge. Retrieved from http://www.dspace.cam.ac.uk/handle/1810/244235https://www.repository.cam.ac.uk/bitstream/1810/244235/2/license.txt ; https://www.repository.cam.ac.uk/bitstream/1810/244235/5/thesis.pdf.txt ; https://www.repository.cam.ac.uk/bitstream/1810/244235/3/thesis.pdf.txt ; https://www.repository.cam.ac.uk/bitstream/1810/244235/6/thesis.pdf.jpg

Chicago Manual of Style (16^th Edition):

Borghesi, Giulio. “Autoignition in turbulent two-phase flows.” 2013. Doctoral Dissertation, University of Cambridge. Accessed April 13, 2021. http://www.dspace.cam.ac.uk/handle/1810/244235https://www.repository.cam.ac.uk/bitstream/1810/244235/2/license.txt ; https://www.repository.cam.ac.uk/bitstream/1810/244235/5/thesis.pdf.txt ; https://www.repository.cam.ac.uk/bitstream/1810/244235/3/thesis.pdf.txt ; https://www.repository.cam.ac.uk/bitstream/1810/244235/6/thesis.pdf.jpg.

MLA Handbook (7^th Edition):

Borghesi, Giulio. “Autoignition in turbulent two-phase flows.” 2013. Web. 13 Apr 2021.

Vancouver:

Borghesi G. Autoignition in turbulent two-phase flows. [Internet] [Doctoral dissertation]. University of Cambridge; 2013. [cited 2021 Apr 13]. Available from: http://www.dspace.cam.ac.uk/handle/1810/244235https://www.repository.cam.ac.uk/bitstream/1810/244235/2/license.txt ; https://www.repository.cam.ac.uk/bitstream/1810/244235/5/thesis.pdf.txt ; https://www.repository.cam.ac.uk/bitstream/1810/244235/3/thesis.pdf.txt ; https://www.repository.cam.ac.uk/bitstream/1810/244235/6/thesis.pdf.jpg.

Council of Science Editors:

Borghesi G. Autoignition in turbulent two-phase flows. [Doctoral Dissertation]. University of Cambridge; 2013. Available from: http://www.dspace.cam.ac.uk/handle/1810/244235https://www.repository.cam.ac.uk/bitstream/1810/244235/2/license.txt ; https://www.repository.cam.ac.uk/bitstream/1810/244235/5/thesis.pdf.txt ; https://www.repository.cam.ac.uk/bitstream/1810/244235/3/thesis.pdf.txt ; https://www.repository.cam.ac.uk/bitstream/1810/244235/6/thesis.pdf.jpg

University of Waterloo

2. Milford, Adrian. Investigation of an Inhomogeneous Mixing Model for Conditional Moment Closure Applied to Autoignition.

Degree: 2010, University of Waterloo

URL: http://hdl.handle.net/10012/5102

► Autoignition of high pressure methane jets at engine relveant conditions within a shock tube is investigated using Conditional Moment Closure (CMC). The impact of two… (more)

▼ Autoignition of high pressure methane jets at engine relveant conditions within a shock tube is investigated using Conditional Moment Closure (CMC). The impact of two commonly used approximations applied in previous work is examined, the assumption of homogeneous turbulence in the closure of the micro-mixing term and the assumption of negligible radial variation of terms within the CMC equations. In the present work two formulations of an inhomogeneous mixing model are implemented, both utilizing the β -PDF, but diﬀering in the respective conditional velocity closure that is applied. The common linear model for conditional velocity is considered, in addition to the gradient diﬀusion model. The validity of cross-stream averaging the CMC equations is examined by comparing results from two-dimensional (axial and radial) solution of the CMC equations with cross-stream averaged results. The CMC equations are presented and all terms requiring closure are discussed. So- lution of the CMC equations is decoupled from the ﬂow ﬁeld solution using the frozen mixing assumption. Detailed chemical kinetics are implemented. The CMC equations are discretized using ﬁnite diﬀerences and solved using a fractional step method. To maintain consistency between the mixing model and the mixture fraction variance equation, the scalar dissipation rate from both implementations of the inhomogeneous model are scaled. The autoignition results for ﬁve air temperatures are compared with results obtained using homogeneous mixing models and experimental data. The gradient diﬀusion conditional velocity model is shown to produce diverging be- haviour in low probability regions. The corresponding proﬁles of conditional scalar dis- sipation rate are negatively impacted with the use of the gradient model, as unphysical behaviour at lean mixtures within the core of the fuel jet is observed. The predictions of ignition delay and location from the Inhomogeneous-Linear model are very close to the homogeneous mixing model results. The Inhomogeneous-Gradient model yields longer ig- nition delays and ignition locations further downstream. This is inﬂuenced by the higher scalar dissipation rates at lean mixtures resulting from the divergent behaviour of the gradient conditional velocity model. The ignition delays obtained by solving the CMC equations in two dimensions are in excellent agreement with the cross-stream averaged values, but the ignition locations are predicted closer to the injector.

Subjects/Keywords: Autoignition; CMC

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Milford, A. (2010). Investigation of an Inhomogeneous Mixing Model for Conditional Moment Closure Applied to Autoignition. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/5102

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Milford, Adrian. “Investigation of an Inhomogeneous Mixing Model for Conditional Moment Closure Applied to Autoignition.” 2010. Thesis, University of Waterloo. Accessed April 13, 2021. http://hdl.handle.net/10012/5102.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Milford, Adrian. “Investigation of an Inhomogeneous Mixing Model for Conditional Moment Closure Applied to Autoignition.” 2010. Web. 13 Apr 2021.

Vancouver:

Milford A. Investigation of an Inhomogeneous Mixing Model for Conditional Moment Closure Applied to Autoignition. [Internet] [Thesis]. University of Waterloo; 2010. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/10012/5102.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Milford A. Investigation of an Inhomogeneous Mixing Model for Conditional Moment Closure Applied to Autoignition. [Thesis]. University of Waterloo; 2010. Available from: http://hdl.handle.net/10012/5102

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Cambridge

3. Borghesi, Giulio. Autoignition in turbulent two-phase flows.

Degree: PhD, 2013, University of Cambridge

URL: https://doi.org/10.17863/CAM.14033 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.566193

► This dissertation deals with the numerical investigation of the physics of sprays autoigniting at diesel engine conditions using Direct Numerical Simulations (DNS), and with the… (more)

▼ This dissertation deals with the numerical investigation of the physics of sprays autoigniting at diesel engine conditions using Direct Numerical Simulations (DNS), and with the modelling of droplet related effects within the Conditional Moment Closure (CMC) method for turbulent non-premixed combustion. The dissertation can be split in four different sections, with the content of each being summarized below. The first part of the dissertation introduces the equations that govern the temporal and spatial evolution of a turbulent reacting flow, and provides an extensive review of the CMC method for both single and two-phase flows. The problem of modelling droplet related effects in the CMC transport equations is discussed in detail, and physically-sound models for the unclosed terms that appear in these equations and that are affected by the droplet presence are derived. The second part of the dissertation deals with the application of the CMC method to the numerical simulation of several n-heptane sprays igniting at conditions relevant to diesel engine combustion. Droplet-related terms in the CMC equations were closed with the models developed in the first part of the dissertation. For all conditions investigated, CMC could correctly capture the ignition, propagation and anchoring phases of the spray flame. Inclusion of droplet terms in the CMC equations had little influence on the numerical predictions, in line with the findings of other authors. The third part of the dissertation presents a DNS study on the autoignition of n-heptane sprays at high pressure / low temperature conditions. The analysis revealed that spray ignition occurs first in well-mixed locations with a specific value of the mixture fraction. Changes in the operating conditions (initial turbulence intensity of the background gas, global equivalence ratio in the spray region, initial droplet size distribution) affected spray ignition through changes in the mixture formation process. For each spray, a characteristic ignition delay time and a characteristic droplet evaporation time could be defined. The ratio between these time scales was suggested as a key parameter for controlling the ignition delay of the spray. The last part of the dissertation exploits the DNS simulations to perform an a priori analysis of the applicability of the CMC method to autoigniting sprays. The study revealed that standard models for the mixing quantities used in CMC provide poor approximations in two-phase flows, and are partially responsible for the poor prediction of the ignition delay time. It was also observed that first-order closure of the chemical source terms performs poorly during the onset of ignition, suggesting that second-order closures may be more appropriate for studying spray autoignition problems. The contribution of the work presented in this dissertation is to provides a detailed insight into the physics of spray autoignition at diesel engine conditions, to propose and derive original methods for incorporating droplet evaporation effects within CMC in a…

Subjects/Keywords: 620; CFD; Diesel engine; DNS; Autoignition

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Borghesi, G. (2013). Autoignition in turbulent two-phase flows. (Doctoral Dissertation). University of Cambridge. Retrieved from https://doi.org/10.17863/CAM.14033 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.566193

Chicago Manual of Style (16^th Edition):

Borghesi, Giulio. “Autoignition in turbulent two-phase flows.” 2013. Doctoral Dissertation, University of Cambridge. Accessed April 13, 2021. https://doi.org/10.17863/CAM.14033 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.566193.

MLA Handbook (7^th Edition):

Borghesi, Giulio. “Autoignition in turbulent two-phase flows.” 2013. Web. 13 Apr 2021.

Vancouver:

Borghesi G. Autoignition in turbulent two-phase flows. [Internet] [Doctoral dissertation]. University of Cambridge; 2013. [cited 2021 Apr 13]. Available from: https://doi.org/10.17863/CAM.14033 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.566193.

Council of Science Editors:

Borghesi G. Autoignition in turbulent two-phase flows. [Doctoral Dissertation]. University of Cambridge; 2013. Available from: https://doi.org/10.17863/CAM.14033 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.566193

University of Melbourne

4. FOONG, TIEN MUN. On the autoignition of ethanol/gasoline blends in spark-ignition engines.

Degree: 2013, University of Melbourne

URL: http://hdl.handle.net/11343/38517

► Ethanol shows significant potential for improving both the efficiency and emissions of spark-ignition engines. It can be made from renewable or waste sources, in which… (more)

▼ Ethanol shows significant potential for improving both the efficiency and emissions of spark-ignition engines. It can be made from renewable or waste sources, in which case its use can substantially reduce the emission of greenhouse gases. However, there is still some uncertainty as to the best use of ethanol in spark ignition engines. This uncertainty is largely related to its blending with gasoline, and the susceptibility of the resulting mixture to the onset of autoignition - a form of uncontrolled combustion that reduces engine performance and leads to engine damage. This work studies the autoignition of ethanol blended with gasoline and its surrogates in three parts. The octane numbers and the blending behaviour of ethanol with gasoline and its surrogates are first presented. The effect of charge cooling of ethanol on the octane numbers is then examined. Finally, the key parameters and mechanisms leading to the autoignition of these fuel blends are identified and analysed using numerical simulations. The presented work shows that both n-heptane, isooctane and their Primary Reference Fuels blend synergistically with ethanol, whilst toluene blends antagonistically. This finding appears to explain the different reported trends in the octane numbers of ethanol/gasoline blends, and also has implications for fuel design. Also, since the standard Research Octane Number (RON) test is influenced by both the fuel's charge cooling and its autoignition chemistry, the proposed, 'modified' RON test appears to be a more practical means of examining the significance of the autoignition chemistry of various fuels. Finally, nitric oxide (NO) is shown to significantly affect the autoignition of these fuel blends. However, considerable uncertainty is present in the chemical interaction of ethanol with isooctane, n-heptane and toluene, and that of NO with different gasoline surrogates and ethanol, suggesting that further experiment and modelling are required.

Subjects/Keywords: ethanol; gasoline; autoignition; octane number; charge cooling

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

FOONG, T. M. (2013). On the autoignition of ethanol/gasoline blends in spark-ignition engines. (Doctoral Dissertation). University of Melbourne. Retrieved from http://hdl.handle.net/11343/38517

Chicago Manual of Style (16^th Edition):

FOONG, TIEN MUN. “On the autoignition of ethanol/gasoline blends in spark-ignition engines.” 2013. Doctoral Dissertation, University of Melbourne. Accessed April 13, 2021. http://hdl.handle.net/11343/38517.

MLA Handbook (7^th Edition):

FOONG, TIEN MUN. “On the autoignition of ethanol/gasoline blends in spark-ignition engines.” 2013. Web. 13 Apr 2021.

Vancouver:

FOONG TM. On the autoignition of ethanol/gasoline blends in spark-ignition engines. [Internet] [Doctoral dissertation]. University of Melbourne; 2013. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/11343/38517.

Council of Science Editors:

FOONG TM. On the autoignition of ethanol/gasoline blends in spark-ignition engines. [Doctoral Dissertation]. University of Melbourne; 2013. Available from: http://hdl.handle.net/11343/38517

University of Sydney

5. MacFarlane, Andrew Ralph William. An experimental investigation into the role of autoignition in turbulent flame stabilisation .

Degree: 2019, University of Sydney

URL: http://hdl.handle.net/2123/20400

► This thesis presents experimental and complimentary numerical results based on a turbulent jet in a hot coflow burner (JHC). The thesis focuses on understanding and… (more)

▼ This thesis presents experimental and complimentary numerical results based on a turbulent jet in a hot coflow burner (JHC). The thesis focuses on understanding and exploring the relative importance of autoignition in the flame stabilisation process for the conditions, temperatures and fuels considered. The influence of fuel type is explored using a range of gaseous fuels including: alkanes, alkenes, H2 and dimethyl ether (DME). High-speed (10 kHz) measurements of chemiluminescence and sound are applied to all flame cases, for all fuels, the measurements are used to temporally resolve the interaction of the flame base with ignition kernels. Similar flame-base and ignition kernel interaction characteristics are found for all fuels where the formation and merging of rapidly growing ignition kernels stabilise these flames. A measurement campaign employing 10 kHz OH and CH2O Planar Laser Induced Fluorescence combined with volumetric chemiluminescence imaging is applied to the ignition kernel formation region in DME flames. The measurements identify regions of low and high-temperatures respectively, with their spatial overlap representing heat release. The kernel heat release measurements indicate that differing degrees of autoignition stabilisation occurs for DME flames, specific to high and low coflow temperature flames. High coflow temperature flames produce lower heat release ignition-kernels; hence these flames are believed to have reduced dependence on autoignition for stability. Zero-dimensional and one-dimensional numerical simulation results, obtained in this thesis, agree with the findings from the hot coflow experiments. The 0-D ignition delay times are shown to successfully capture the different fuels lift-off height sensitivities with coflow temperature. The sensitivity of relatively low coflow temperatures are particularly well represented by delay times, with a linear correlation between delay times and experimental lift-off heights. To replicate the strained and diffusive conditions induced by the JHC burner, unsteady 1-D counter-flow simulations were applied. These simulations, using DME, identify that for high coflow temperature flames, the ignition kernels produce lower heat release, since they are igniting leaner. Using CH4 with the same counter-flow setup, the effect of strain-rate was explored. It was found that increased strain rate delays ignition, since the unity balance between diffusion and production fluxes of CH2O is also delayed. Furthermore, under autoignition conditions, the counter-flow solver, in addition to a premixed solver, show CH2O convection and production fluxes increase, with a corresponding diffusive decrease.

Subjects/Keywords: turbulent combustion; autoignition; experimental; laser diagnostics

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

MacFarlane, A. R. W. (2019). An experimental investigation into the role of autoignition in turbulent flame stabilisation . (Thesis). University of Sydney. Retrieved from http://hdl.handle.net/2123/20400

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

MacFarlane, Andrew Ralph William. “An experimental investigation into the role of autoignition in turbulent flame stabilisation .” 2019. Thesis, University of Sydney. Accessed April 13, 2021. http://hdl.handle.net/2123/20400.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

MacFarlane, Andrew Ralph William. “An experimental investigation into the role of autoignition in turbulent flame stabilisation .” 2019. Web. 13 Apr 2021.

Vancouver:

MacFarlane ARW. An experimental investigation into the role of autoignition in turbulent flame stabilisation . [Internet] [Thesis]. University of Sydney; 2019. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/2123/20400.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

MacFarlane ARW. An experimental investigation into the role of autoignition in turbulent flame stabilisation . [Thesis]. University of Sydney; 2019. Available from: http://hdl.handle.net/2123/20400

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of New South Wales

6. Zhang, Haoyang. Modelling of stratified charge compression ignition engines.

Degree: Photovoltaics & Renewable Energy Engineering, 2014, University of New South Wales

URL: http://handle.unsw.edu.au/1959.4/53630 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12325/SOURCE02?view=true

► Homogeneous charge compression-ignition (HCCI) engines have been considered to hold potential for next generation internal combustion engines with low emissions and low fuel-consumption. However, some… (more)

▼ Homogeneous charge compression-ignition (HCCI) engines have been considered to hold potential for next generation internal combustion engines with low emissions and low fuel-consumption. However, some technical hurdles, such as low combustion-efficiency at low load and excessive pressure-rise rate (PRR) at high load, significantly challenge its practical application.In this thesis, fundamental studies of fuel ignition response to thermal stratification were first conducted by using direct numerical simulations coupled with a detailed chemistry mechanism. For a two-stage ignition fuel with negative temperature coefficient (NTC) behaviour, dimethyl ether, the auto-ignition regime was found to depend strongly on the initial temperature. Molecular diffusion was found to be negligible in comparison to chemical reaction when the initial temperature fell inside NTC regime; however, once the initial temperature was outside NTC regime, diffusion became relatively more significant. Diffusion was also observed to decrease with an increase of the length-scale. PRR was found to be reduced with thermal stratification, but this was also dependent on the mean temperature.Then, non-reacting multi-dimensional engine modelling was conducted to investigate the effects of fuel direct injection on the resulting mixture distribution. It was found that as the start of injection was retarded, more fuel was concentrated in the central areas of the cylinder, leading to a potential increase of combustion efficiency and potential reduction of carbon monoxide and unburned hydrocarbons, but a potential increase of excessive nitrogen oxides. Droplet-wall interaction and spray-to-spray interaction were observed to play essential roles in fuel distribution. Furthermore, the use of high injection pressure can enhance the mixing, while the use of high swirl ratio and low injection pressure showed negative effects on the global mixing.Finally, reacting engine simulations were carried on to study the effects of thermal stratification on a fully premixed HCCI engine fuelled by ethanol. These studies pointed out many challenges with attempts to model HCCI predictively, owing to strong sensitivities to initial charge temperature and pressure, wall temperatures, residual gas composition, initial turbulence intensity and models for its evolution and wall models. These sensitivities were analysed and used to construct an optimised model that agreed quite well with experimental pressure traces and associated quantities such as the PRR, the indicated mean effective pressure, and the thermal efficiency. Analysis of the optimised model results was used to determine that enhanced thermal stratification demonstrated a significant reduction of the PRR. The degree of the reduction was found to depend on the penetration of thermal stratification into the bulk-gas regions. In addition, turbulence played an important role in the control combustion phasing primarily by altering the distributions of thermal stratification. Advisors/Committee Members: Hawkes, Evatt, Photovoltaics & Renewable Energy Engineering, Faculty of Engineering, UNSW, Kook, Sanghoon, Mechanical & Manufacturing Engineering, Faculty of Engineering, UNSW.

Subjects/Keywords: CFD; HCCI; SCCI; Autoignition; Direct injection

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Zhang, H. (2014). Modelling of stratified charge compression ignition engines. (Doctoral Dissertation). University of New South Wales. Retrieved from http://handle.unsw.edu.au/1959.4/53630 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12325/SOURCE02?view=true

Chicago Manual of Style (16^th Edition):

Zhang, Haoyang. “Modelling of stratified charge compression ignition engines.” 2014. Doctoral Dissertation, University of New South Wales. Accessed April 13, 2021. http://handle.unsw.edu.au/1959.4/53630 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12325/SOURCE02?view=true.

MLA Handbook (7^th Edition):

Zhang, Haoyang. “Modelling of stratified charge compression ignition engines.” 2014. Web. 13 Apr 2021.

Vancouver:

Zhang H. Modelling of stratified charge compression ignition engines. [Internet] [Doctoral dissertation]. University of New South Wales; 2014. [cited 2021 Apr 13]. Available from: http://handle.unsw.edu.au/1959.4/53630 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12325/SOURCE02?view=true.

Council of Science Editors:

Zhang H. Modelling of stratified charge compression ignition engines. [Doctoral Dissertation]. University of New South Wales; 2014. Available from: http://handle.unsw.edu.au/1959.4/53630 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:12325/SOURCE02?view=true

Universitat Politècnica de València

7. López Pintor, Darío. Theoretical and experimental study on the autoignition phenomena of homogeneous reactive mixtures .

Degree: 2017, Universitat Politècnica de València

URL: http://hdl.handle.net/10251/90642

► The main objective of this Thesis is the study of the autoignition phenomenon of reactive mixtures from a theoretical and experimental point of view. A… (more)

▼ The main objective of this Thesis is the study of the autoignition phenomenon of reactive mixtures from a theoretical and experimental point of view. A wide parametric study has been carried out in a Rapid Compression-Expansion Machine (RCEM) for different initial temperatures, compression ratios, equivalence ratios and molar fractions of oxygen (by using synthetic EGR) for different fuels. The ignition delay referred to cool flames (if it can be identified), as well as the ignition delay referred to the high-temperature stage of the ignition, have been experimentally obtained and their trends have been explained regarding the chemical kinetics of each fuel. The different effects of the species that compose the synthetic EGR on the ignition delay have been studied, decoupling the thermodynamic effects from the chemical ones. Different compositions have been taken into account to generate the synthetic EGR, and validation limits have been obtained for each mixture. The thermodynamic and the chemical effects have shown to be opposed, while the dominant one is different depending on the working temperature. Several chemical kinetic mechanisms have been validated by comparison to the experimental results. A detailed mechanism for iso-octane and n-heptane blends and a reduced mechanisms for n-dodecane have been analyzed. Moreover, a sub-model for the generation and decay of excited OH* has been validated by comparison to chemiluminescence and spectroscopy results. The different radiation sources have been studied for iso-octane and n-heptane by means of spectroscopy techniques. Besides, chemiluminescence measurements filtered at 310nm (OH* emission wavelength) have been performed in order to analyze the generalization and propagation velocity of the autoignition front. The ignition propagation has shown to depend on the thermodynamic conditions reached in the combustion chamber when the first ignition spot occurs and not on the global reactivity of the mixture. Furthermore, two different radiation sources have been found at 310nm in the spectroscopic analysis depending on the ignition intensity: the decay of the OH* radical from excited to ground state and the oxidation of CO to CO2 (CO continuum). However, these optical techniques have been applied only in the experiments carried out with iso-octane and n-heptane due to technical limitations. Finally, a new predictive model has been theoretically developed starting from the Glassman's model for autoignition. This method is based on modeling the accumulation rate of chain carriers up to reach their critical concentration (obtaining the ignition delay referred to cool flames) and, afterwards, modeling the disappearance rate of such chain carriers up to their consumption (when the maximum heat release rate is reached, obtaining the ignition delay referred to the high-temperature stage of the process). The predictive capability of the model has been compared to the ability of other methods that can be found in the literature, such as the Livengood & Wu integral method. The… Advisors/Committee Members: Desantes Fernández, José Mª (advisor), López Sánchez, José Javier (advisor).

Subjects/Keywords: autoignition; chemical kinetics; sequential autoignition; autoignition propagation; chemiluminescence; spectroscopy; RCEM; rapid compression-expansion machine; CHEMKIN; ignition delay; ignition modelling; chain carriers; ignition prediction

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

López Pintor, D. (2017). Theoretical and experimental study on the autoignition phenomena of homogeneous reactive mixtures . (Doctoral Dissertation). Universitat Politècnica de València. Retrieved from http://hdl.handle.net/10251/90642

Chicago Manual of Style (16^th Edition):

López Pintor, Darío. “Theoretical and experimental study on the autoignition phenomena of homogeneous reactive mixtures .” 2017. Doctoral Dissertation, Universitat Politècnica de València. Accessed April 13, 2021. http://hdl.handle.net/10251/90642.

MLA Handbook (7^th Edition):

López Pintor, Darío. “Theoretical and experimental study on the autoignition phenomena of homogeneous reactive mixtures .” 2017. Web. 13 Apr 2021.

Vancouver:

López Pintor D. Theoretical and experimental study on the autoignition phenomena of homogeneous reactive mixtures . [Internet] [Doctoral dissertation]. Universitat Politècnica de València; 2017. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/10251/90642.

Council of Science Editors:

López Pintor D. Theoretical and experimental study on the autoignition phenomena of homogeneous reactive mixtures . [Doctoral Dissertation]. Universitat Politècnica de València; 2017. Available from: http://hdl.handle.net/10251/90642

Penn State University

8. Elies, Daniel Jason. Autoignition of Hydrogen and Syngas with Air in a Turbulent Flow Reactor.

Degree: 2012, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/16294

► A good deal of attention has been given recently to combustion of syngas in gas turbines used for power generation. Syngas is a mixture of… (more)

▼ A good deal of attention has been given recently to combustion of syngas in gas turbines used for power generation. Syngas is a mixture of hydrogen and carbon monoxide produced from coal gasification, a process where coal is partially oxidized producing a gaseous product with high concentrations of hydrogen and carbon monoxide. Although coal gasification is not a new technology, recent interest has been spurred by concerns about climate change due in large part to increased levels of carbon dioxide in the atmosphere. Coal-fired power plants in 2011 produced approximately 46% of the electricity used in the United States, but contributed 79% of the energy related carbon dioxide emissions. The reason that coal contributes such a large portion of the carbon dioxide emissions is that the carbon to hydrogen ratio of coal is high as compared to other hydrocarbon fuels. As a result, more of the energy released from burning coal comes from the oxidation of carbon rather than hydrogen, which increases the amount of carbon dioxide emitted per kilowatt hour. To reduce these high carbon dioxide emissions, the use of syngas as fuel is part of the "Clean Coal" effort that will use carbon sequestration to remove carbon dioxide from the combustion products and store it underground. One of the challenges of using syngas as a fuel is the variable composition in terms of the amount of hydrogen and carbon monoxide present in the fuel. This variable composition results from the wide variety of coal that can be used to produce syngas. These compositional variations alter the combustion characteristics of syngas. Additionally, present gas turbine technology for power generation utilizes lean-premixed conditions to reduce oxides of nitrogen formation, that is fuel and hot air from the compressor are premixed prior to combustion. If premixed syngas and air was to ignite in the gas turbine premixer, severe damage would occur. Consequently, one of the combustion characteristics of particular importance is the autoignition time. Autoignition is a measure of the time for a mixture of fuel and oxidizer at some elevated temperature to spontaneously ignite. Thus, the present study specifically addresses measurements of the autoignition time for hydrogen and hydrogen/carbon monoxide mixtures under conditions relevant to gas turbines used for power generation. Experiments were conducted using a turbulent flow reactor for the purpose of examining autoignition times for hydrogen and hydrogen/carbon monoxide mixtures with air. Experiments with only hydrogen as fuel were conducted at experimental conditions including ignition delay times of 130 and 210 ms, equivalence ratios of 0.375 and 0.750, and pressures of 10 and 15 atm. Temperatures could be varied between 800 and 900 K using a combination of an electric heater and a hydrogen and oxygen fueled preburner. Experiments were also conducted with a mixture of hydrogen and carbon monoxide, to simulate Syngas, at a pressure of 15 atm, an ignition delay time of 130 ms, and at equivalence… Advisors/Committee Members: Robert John Santoro, Thesis Advisor/Co-Advisor.

Subjects/Keywords: autoignition; flow reactor; syngas; hydrogen; premixed; ignition delay

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Elies, D. J. (2012). Autoignition of Hydrogen and Syngas with Air in a Turbulent Flow Reactor. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/16294

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Elies, Daniel Jason. “Autoignition of Hydrogen and Syngas with Air in a Turbulent Flow Reactor.” 2012. Thesis, Penn State University. Accessed April 13, 2021. https://submit-etda.libraries.psu.edu/catalog/16294.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Elies, Daniel Jason. “Autoignition of Hydrogen and Syngas with Air in a Turbulent Flow Reactor.” 2012. Web. 13 Apr 2021.

Vancouver:

Elies DJ. Autoignition of Hydrogen and Syngas with Air in a Turbulent Flow Reactor. [Internet] [Thesis]. Penn State University; 2012. [cited 2021 Apr 13]. Available from: https://submit-etda.libraries.psu.edu/catalog/16294.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Elies DJ. Autoignition of Hydrogen and Syngas with Air in a Turbulent Flow Reactor. [Thesis]. Penn State University; 2012. Available from: https://submit-etda.libraries.psu.edu/catalog/16294

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

9. Moyer, Orin D. AUTOIGNITION OF N-HEPTANE, ETHANOL, METHYL HEXANOATE AND METHYL 3-HEXENOATE IN A MOTORED ENGINE .

Degree: 2011, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/12579

► Autoignition of fuel blends consisting of ethanol, n-heptane, and two biodiesel surrogates: methyl hexanoate (mhx) and methyl 3-hexenoate (m3h) were studied in a Cooperative Fuels… (more)

▼ Autoignition of fuel blends consisting of ethanol, n-heptane, and two biodiesel surrogates: methyl hexanoate (mhx) and methyl 3-hexenoate (m3h) were studied in a Cooperative Fuels Research (CFR) motored-engine at equivalence ratios (¥Õ) 0.25 and 0.50 (typical ¥Õ of HCCI and diesel engine operation) with an intake temperature of 155¨¬C. The objectives of the study were to further understand the low-temperature oxidation chemistry of the four pure fuels and their blends, to compare the effect of a saturated and unsaturated methyl ester containing the same number of carbon atoms as n-heptane, to observe the intermediate species by GS-MS and GC-FID examination of exhaust samples taken prior to the autoignition event, and to study the impact of ethanol on each of the methyl esters . The compression ratio of the CFR engine was gradually increased from the lowest point to the point where the onset of high-temperature heat-release (HTHR) occurred. Within the test range of this research, all fuels and their blends where driven to their critical compression ratio (the onset of HTHR); and it was observed through heat-release analysis and of CO emissions trends comparison that the saturated methyl ester (mhx) exhibited cool-flame behavior while its unsaturated counterpart did not. This observation agrees with previous studies by Zhang and Boehman that the presence of a double-bond in the aliphatic chain suppresses cool-flame behavior by inhibiting isomerization reactions of peroxy radicals that are key to low-temperature oxidation chemistry. All blends with ethanol had a roughly linear effect on the delay of the onset of HTHR. Another trend observed was that blends with increasing ethanol content had a lower magnitude of LTHR and an onset occurring further after top dead center at the same compression ratio indicating that blends with increasing ethanol content are less reactive in the low-temperature regime. Interestingly, the magnitude of LTHR increases with increasing compression ratio for mhx/hept blends while the magnitude of LTHR was noted to decrease for pure mhx. Further, it was observed that the magnitude of the LTHR at the critical compression ratio decreases with increasing ethanol content for pure mhx and its n-heptane blends as a result of the inhibiting effect of ethanol on ignition. Advisors/Committee Members: Dr Boehman, Thesis Advisor/Co-Advisor, Andre Louis Boehman, Thesis Advisor/Co-Advisor.

Subjects/Keywords: methyl hexenoate; C7; motored engine; esters; biodiesel; CFR; methyl hexanaote; autoignition

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Moyer, O. D. (2011). AUTOIGNITION OF N-HEPTANE, ETHANOL, METHYL HEXANOATE AND METHYL 3-HEXENOATE IN A MOTORED ENGINE . (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/12579

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Moyer, Orin D. “AUTOIGNITION OF N-HEPTANE, ETHANOL, METHYL HEXANOATE AND METHYL 3-HEXENOATE IN A MOTORED ENGINE .” 2011. Thesis, Penn State University. Accessed April 13, 2021. https://submit-etda.libraries.psu.edu/catalog/12579.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Moyer, Orin D. “AUTOIGNITION OF N-HEPTANE, ETHANOL, METHYL HEXANOATE AND METHYL 3-HEXENOATE IN A MOTORED ENGINE .” 2011. Web. 13 Apr 2021.

Vancouver:

Moyer OD. AUTOIGNITION OF N-HEPTANE, ETHANOL, METHYL HEXANOATE AND METHYL 3-HEXENOATE IN A MOTORED ENGINE . [Internet] [Thesis]. Penn State University; 2011. [cited 2021 Apr 13]. Available from: https://submit-etda.libraries.psu.edu/catalog/12579.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Moyer OD. AUTOIGNITION OF N-HEPTANE, ETHANOL, METHYL HEXANOATE AND METHYL 3-HEXENOATE IN A MOTORED ENGINE . [Thesis]. Penn State University; 2011. Available from: https://submit-etda.libraries.psu.edu/catalog/12579

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

10. Christensen, Michelle Kathleen. Flow Reactor Autoignition Studies of Iso-octane at High Pressures and Low-to-intermediate Temperatures.

Degree: 2012, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/14556

► The trend in internal combustion engine and aviation gas turbine design is moving increasingly toward a computational approach, requiring well-validated chemical kinetics models. Autoignition delay… (more)

▼ The trend in internal combustion engine and aviation gas turbine design is moving increasingly toward a computational approach, requiring well-validated chemical kinetics models. Autoignition delay measurements are among the key set of validation data used by chemical kinetics modelers. Autoignition is an ignition event that occurs when the mixture reaches conditions of temperature, pressure, and equivalence ratio such that the rate of chain branching exceeds the rate of chain termination. In this case there is no external ignition source, such as a spark or initiating flame. Iso-octane, the compound studied in this work, is one of the fuels used to establish the octane rating for gasoline. Recently it has become of further interest as a component in fuel mixtures referred to as surrogate fuel mixtures such as JP-8. These surrogate fuel mixtures consist of only a few compounds that behave chemically in a manner similar to a practical fuel. Studies of autoignition of iso-octane were conducted in a high-pressure flow reactor. A novel methodology was employed in which the minimum equivalence ratio required for ignition was established for specific conditions of pressure, temperature, and residence time. Liquid iso-octane was spray injected into the products of a hydrogen/oxygen/argon preburner, and the resulting vaporized mixture was then rapidly mixed with air in the high-pressure flow reactor. Autoignition delay times were obtained at pressures of 15, 17.5, 20, and 22.5 atm, for a temperature range of 640-850 K. Residence times of approximately 70, 100, 125, 155, and 175 ms were investigated over equivalence ratios ranging from 0.25 to 0.8. Very few previous iso-octane ignition delay studies have investigated the conditions included in the present study. However, the current experiments have some overlapping pressure and temperature conditions (15 atm and 650-850 K) with rapid compression machine experiments. The rapid compression machine results are all for stoichiometric mixtures, whereas the current results are for equivalence ratios ranging from 0.37-0.8. The results from this work are useful for model validation as they are consistent with trends from previous studies and extend into a range of pressures, temperatures, and equivalence ratios not previously investigated. The onset of autoignition for all pressures occurred at approximately 640K. Trends in the results showed that as temperature increased, the threshold equivalence ratio decreased. As temperature increased further into the negative temperature coefficient (NTC) region, the threshold equivalence ratio increased with increasing temperature. The NTC behavior started at temperatures of approximately 700-725K and ended at approximately 775K. At temperatures above 775K, the threshold equivalence ratio again decreased with increasing temperature. Pressure also had a strong effect on ignition delay. For all conditions, as pressure increased the threshold equivalence ratio decreased. Results were compared with two chemical kinetics models. Good agreement… Advisors/Committee Members: Robert John Santoro, Dissertation Advisor/Co-Advisor, Thomas Litzinger, Committee Member, Harold Harris Schobert, Committee Member, Stephen R Turns, Committee Member.

Subjects/Keywords: autoignition; ignition delay time; iso-octane; flow reactor

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Christensen, M. K. (2012). Flow Reactor Autoignition Studies of Iso-octane at High Pressures and Low-to-intermediate Temperatures. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/14556

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Christensen, Michelle Kathleen. “Flow Reactor Autoignition Studies of Iso-octane at High Pressures and Low-to-intermediate Temperatures.” 2012. Thesis, Penn State University. Accessed April 13, 2021. https://submit-etda.libraries.psu.edu/catalog/14556.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Christensen, Michelle Kathleen. “Flow Reactor Autoignition Studies of Iso-octane at High Pressures and Low-to-intermediate Temperatures.” 2012. Web. 13 Apr 2021.

Vancouver:

Christensen MK. Flow Reactor Autoignition Studies of Iso-octane at High Pressures and Low-to-intermediate Temperatures. [Internet] [Thesis]. Penn State University; 2012. [cited 2021 Apr 13]. Available from: https://submit-etda.libraries.psu.edu/catalog/14556.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Christensen MK. Flow Reactor Autoignition Studies of Iso-octane at High Pressures and Low-to-intermediate Temperatures. [Thesis]. Penn State University; 2012. Available from: https://submit-etda.libraries.psu.edu/catalog/14556

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

North Carolina State University

11. Gupta, Kamlesh Govindram. Numerical Studies of H2 and H2/CO Autoignition in Turbulent Jets.

Degree: MS, Mechanical Engineering, 2010, North Carolina State University

URL: http://www.lib.ncsu.edu/resolver/1840.16/162

► The present study is carried out in two parts. In the first part, the autoignition of hydrogen in a turbulent jet with preheated air is… (more)

▼ The present study is carried out in two parts. In the first part, the autoignition of hydrogen in a turbulent jet with preheated air is studied computationally using the stand-alone one-dimensional turbulence (ODT) model. The simulations are based on varying the jet Reynolds number and the mixture pressure. Also, computations are carried out for homogeneous autoignition at different mixture fractions and the same two pressure conditions considered for the jet simulations. The simulations show that autoignition is delayed in the jet configuration relative to the earliest autoignition events in homogeneous mixtures. This delay is primarily due to the presence of scalar dissipation associated with the scalar mixing layer in the jet configuration as well as with the presence of turbulent stirring. Turbulence plays additional roles in the subsequent stages of the autoignition process. Pressure effects also are present during the autoignition process and the subsequent high-temperature combustion stages. These effects may be attributed primarily to the autoignition delay time sensitivity to the mixture conditions and the role of pressure and air preheating on molecular transport properties. The overall trends are such that turbulence increases autoignition delay times and accordingly the ignition length and pressure further contributes to this delay. In the second part of this study, similar autoignition study of mixture of hydrogen and carbon monoxide is conducted. Two different mixture compositions are considered. They correspond to H2:CO:N2 ratios by volume of 15:35:50 and 20:30:50. Each composition is simulated for two oxidizer preheat temperatures and two fuel jet Reynolds numbers at atmospheric pressure. Homogeneous autoignition is carried out for same preheat mixture conditions for comparison with the turbulent jet results. The autoignition delay time recorded for jet cases is lower than the homogeneous autoignition delay time. This is attributed to the differential diffusion of hydrogen, which plays an important and enhancing role of the diffusion of hydrogen into the oxidizer. Advisors/Committee Members: Dr. William Roberts, Committee Member (advisor), Dr. Tiegang Fang, Committee Member (advisor), Dr. Tarek Echekki, Committee Chair (advisor).

Subjects/Keywords: hydrogen; turbulent jets; one-dimensional turbulence model; carbon-monoxide; autoignition

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Gupta, K. G. (2010). Numerical Studies of H2 and H2/CO Autoignition in Turbulent Jets. (Thesis). North Carolina State University. Retrieved from http://www.lib.ncsu.edu/resolver/1840.16/162

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Gupta, Kamlesh Govindram. “Numerical Studies of H2 and H2/CO Autoignition in Turbulent Jets.” 2010. Thesis, North Carolina State University. Accessed April 13, 2021. http://www.lib.ncsu.edu/resolver/1840.16/162.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Gupta, Kamlesh Govindram. “Numerical Studies of H2 and H2/CO Autoignition in Turbulent Jets.” 2010. Web. 13 Apr 2021.

Vancouver:

Gupta KG. Numerical Studies of H2 and H2/CO Autoignition in Turbulent Jets. [Internet] [Thesis]. North Carolina State University; 2010. [cited 2021 Apr 13]. Available from: http://www.lib.ncsu.edu/resolver/1840.16/162.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Gupta KG. Numerical Studies of H2 and H2/CO Autoignition in Turbulent Jets. [Thesis]. North Carolina State University; 2010. Available from: http://www.lib.ncsu.edu/resolver/1840.16/162

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

North Carolina State University

12. Zhang, Sha. Study of Finite-Rate Chemistry Effects on Turbulent Jet Diffusion Flames and Non-homogeneous Autoigntion Using the One-Dimensional Turbulence Model.

Degree: MS, Mechanical Engineering, 2003, North Carolina State University

URL: http://www.lib.ncsu.edu/resolver/1840.16/1257

► In current study Numerical simulation of turbulent combustion process is approached using One Dimensional Turbulence (ODT) model. The ODT model is based on the coupling… (more)

▼ In current study Numerical simulation of turbulent combustion process is approached using One Dimensional Turbulence (ODT) model. The ODT model is based on the coupling of molecular processes (reaction and diffusion) with turbulent transport in a spatially- and temporally-resolved fashion over a one-dimensional domain. The domain corresponds to a transverse (or radial) direction; while, the transient evolution of the thermo-chemical scalars on the 1D domain represents the spatial evolution downstream of the jet inlet. The linear-eddy approach for modeling molecular mixing in turbulent flow involves stochastic simulation on a 1D domain with sufficient resolution to predict all relevant physical length scales properly. Firstly ODT is carried out to predict the hydrogen and air jet diffusion flame with helium dilution in the fuel. The comparison with existing experimental data was made for the numerical result of ODT simulation of jet diffusion flames in both conditional means and rms of scalars of measurements and computational results. Another application of ODT was made in present work to verify the capability of prediction of autoignition (self-ignition) of one of free shear layer flow — jet diffusion flow. Different range of pressure and Reynolds number are set to identify the effects of turbulence intensity and mixture properties on the self-ignition chemistry. Autoignition delay time was studied based on these different conditions. At the same time the ability of the prediction of mixture temperature and species mass fraction profile were tested. A principle numerical result is expected and discussed. Conditional pdf and progress variable were used to analyze the computational result of ODT. Analysis was focus on the temperature growth and the mass fraction distribution of intermediate species and product. Advisors/Committee Members: Dr. Andrey V. Kuznetsov, Committee Member (advisor), Dr. Kevin M. Lyons, Committee Member (advisor), Dr. Tarek Echekki, Committee Chair (advisor).

Subjects/Keywords: autoignition; ODT; turbulent combustion

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Zhang, S. (2003). Study of Finite-Rate Chemistry Effects on Turbulent Jet Diffusion Flames and Non-homogeneous Autoigntion Using the One-Dimensional Turbulence Model. (Thesis). North Carolina State University. Retrieved from http://www.lib.ncsu.edu/resolver/1840.16/1257

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Zhang, Sha. “Study of Finite-Rate Chemistry Effects on Turbulent Jet Diffusion Flames and Non-homogeneous Autoigntion Using the One-Dimensional Turbulence Model.” 2003. Thesis, North Carolina State University. Accessed April 13, 2021. http://www.lib.ncsu.edu/resolver/1840.16/1257.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Zhang, Sha. “Study of Finite-Rate Chemistry Effects on Turbulent Jet Diffusion Flames and Non-homogeneous Autoigntion Using the One-Dimensional Turbulence Model.” 2003. Web. 13 Apr 2021.

Vancouver:

Zhang S. Study of Finite-Rate Chemistry Effects on Turbulent Jet Diffusion Flames and Non-homogeneous Autoigntion Using the One-Dimensional Turbulence Model. [Internet] [Thesis]. North Carolina State University; 2003. [cited 2021 Apr 13]. Available from: http://www.lib.ncsu.edu/resolver/1840.16/1257.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Zhang S. Study of Finite-Rate Chemistry Effects on Turbulent Jet Diffusion Flames and Non-homogeneous Autoigntion Using the One-Dimensional Turbulence Model. [Thesis]. North Carolina State University; 2003. Available from: http://www.lib.ncsu.edu/resolver/1840.16/1257

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Boston University

13. Morrison, Paul. Driving efficiency in design for rare events using metamodeling and optimization.

Degree: MS, Mechanical Engineering, 2015, Boston University

URL: http://hdl.handle.net/2144/16226

► Rare events have very low probability of occurrence but can have significant impact. Earthquakes, volcanoes, and stock market crashes can have devastating impact on those… (more)

Subjects/Keywords: Engineering; Autoignition; Importance sampling; Metamodeling; Optimization; Rare events

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Morrison, P. (2015). Driving efficiency in design for rare events using metamodeling and optimization. (Masters Thesis). Boston University. Retrieved from http://hdl.handle.net/2144/16226

Chicago Manual of Style (16^th Edition):

Morrison, Paul. “Driving efficiency in design for rare events using metamodeling and optimization.” 2015. Masters Thesis, Boston University. Accessed April 13, 2021. http://hdl.handle.net/2144/16226.

MLA Handbook (7^th Edition):

Morrison, Paul. “Driving efficiency in design for rare events using metamodeling and optimization.” 2015. Web. 13 Apr 2021.

Vancouver:

Morrison P. Driving efficiency in design for rare events using metamodeling and optimization. [Internet] [Masters thesis]. Boston University; 2015. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/2144/16226.

Council of Science Editors:

Morrison P. Driving efficiency in design for rare events using metamodeling and optimization. [Masters Thesis]. Boston University; 2015. Available from: http://hdl.handle.net/2144/16226

Wayne State University

14. Zyada, Antowan. Ethanol Autoignition Modeling And Validation At Wide Ranges Of Mixture Temperatures, Pressures, And Equivalence Ratios.

Degree: PhD, Mechanical Engineering, 2018, Wayne State University

URL: https://digitalcommons.wayne.edu/oa_dissertations/2197

► A new ethanol detailed kinetic model with 107 species and 1795 reactions was developed by using the reaction mechanism generator (RMG) and a thorough… (more)

Subjects/Keywords: Autoignition; Combustion images; Ethanol; Ignition delay time; Mechanism; RMG; Mechanical Engineering

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Zyada, A. (2018). Ethanol Autoignition Modeling And Validation At Wide Ranges Of Mixture Temperatures, Pressures, And Equivalence Ratios. (Doctoral Dissertation). Wayne State University. Retrieved from https://digitalcommons.wayne.edu/oa_dissertations/2197

Chicago Manual of Style (16^th Edition):

Zyada, Antowan. “Ethanol Autoignition Modeling And Validation At Wide Ranges Of Mixture Temperatures, Pressures, And Equivalence Ratios.” 2018. Doctoral Dissertation, Wayne State University. Accessed April 13, 2021. https://digitalcommons.wayne.edu/oa_dissertations/2197.

MLA Handbook (7^th Edition):

Zyada, Antowan. “Ethanol Autoignition Modeling And Validation At Wide Ranges Of Mixture Temperatures, Pressures, And Equivalence Ratios.” 2018. Web. 13 Apr 2021.

Vancouver:

Zyada A. Ethanol Autoignition Modeling And Validation At Wide Ranges Of Mixture Temperatures, Pressures, And Equivalence Ratios. [Internet] [Doctoral dissertation]. Wayne State University; 2018. [cited 2021 Apr 13]. Available from: https://digitalcommons.wayne.edu/oa_dissertations/2197.

Council of Science Editors:

Zyada A. Ethanol Autoignition Modeling And Validation At Wide Ranges Of Mixture Temperatures, Pressures, And Equivalence Ratios. [Doctoral Dissertation]. Wayne State University; 2018. Available from: https://digitalcommons.wayne.edu/oa_dissertations/2197

15. Evans, Michael J. Flame Stabilisation in the Transition to MILD Combustion.

Degree: 2017, University of Adelaide

URL: http://hdl.handle.net/2440/119081

► Emissions reduction and energy management are current and future concerns for governments and industries alike. The primary source of energy worldwide for electricity, air transport… (more)

▼ Emissions reduction and energy management are current and future concerns for governments and industries alike. The primary source of energy worldwide for electricity, air transport and industrial processes is combustion. Moderate or intense low oxygen dilution (MILD) combustion offers improved thermal efficiency and a significant reduction of CO and NOx pollutants, soot and thermo-acoustic instabilities compared to conventional combustion. Whilst combustion in the MILD regime offers considerable advantages over conventional combustion, neither the structure of reacting jets under MILD conditions, nor the boundaries of the MILD regime are currently well understood. This work, therefore, serves to fill this gap in the understanding of flame structure near the boundaries of the MILD regime. The MILD combustion regime has been previously investigated experimentally and numerically in premixed reactors and non-premixed flames. In this study, definitions of MILD combustion are compared and contrasted, with the phenomenological premixed description of MILD combustion extended to describe non-premixed flames. A simple criterion is derived analytically which offers excellent agreement with observations of previously studied cases and new, non-premixed MILD and autoignitive flames presented in this work. This criterion facilitates a simple, predictive approach to distinguish MILD combustion, autoignitive flames, and the transition between the two regimes. The adequacy of simplified reactors as a tool for predicting non-premixed ignition behaviour in the transition between MILD combustion and autoignition has not previously been resolved, and is addressed in this work. The visual lift-off behaviour seen in the transition between MILD combustion and conventional autoignitive flames seen experimentally is successfully replicated using simplified reactors. The location of the visible flame base in a jet-in-hot-coflow burner is shown to be highly sensitive to the relative location of the most reactive mixture fraction and the high strain-rate shear layer due to the strong coupling of between ignition chemistry and the underlying flow-field. Previous studies have demonstrated a strong dependence of ignition delay times to significant concentrations of minor species. Simulations presented in this work demonstrate that small concentrations of the hydroxyl radical (OH), similar to those expected in practical environments, significantly affect ignition delay and intensity of non-premixed MILD combustion, however have little effect on autoignitive flames. Importantly, such concentrations of OH do not result in a change in flame structure for the cases investigated. Whilst these results stress the importance of minor species in modelling the transient ignition of non-premixed MILD combustion, steady-state simulations do not demonstrate the same sensitivity to concentrations of minor species expected in hot combustion products. These results suggest that the temperature and oxygen concentration in the oxidant stream are the most important… Advisors/Committee Members: Medwell, Paul (advisor), School of Mechanical Engineering (school).

Subjects/Keywords: MILD combustion; autoignition; lifted flames; flamelet theory; eddy dissipation concept (EDC)

14 more images…

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Evans, M. J. (2017). Flame Stabilisation in the Transition to MILD Combustion. (Thesis). University of Adelaide. Retrieved from http://hdl.handle.net/2440/119081

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Evans, Michael J. “Flame Stabilisation in the Transition to MILD Combustion.” 2017. Thesis, University of Adelaide. Accessed April 13, 2021. http://hdl.handle.net/2440/119081.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Evans, Michael J. “Flame Stabilisation in the Transition to MILD Combustion.” 2017. Web. 13 Apr 2021.

Vancouver:

Evans MJ. Flame Stabilisation in the Transition to MILD Combustion. [Internet] [Thesis]. University of Adelaide; 2017. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/2440/119081.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Evans MJ. Flame Stabilisation in the Transition to MILD Combustion. [Thesis]. University of Adelaide; 2017. Available from: http://hdl.handle.net/2440/119081

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Iowa State University

16. Reinbacher, Fynn. Hotspot characterization and detonation initiation in thermally stratified reactive mixtures.

Degree: 2018, Iowa State University

URL: https://lib.dr.iastate.edu/etd/16442

► In a society powered by combustion, a detailed understanding of the underlying physics is imperative. Among the main challenges in the development of high performance,… (more)

▼ In a society powered by combustion, a detailed understanding of the underlying physics is imperative. Among the main challenges in the development of high performance, high efficiency advanced gasoline engines are end-gas, auto- or pre-ignition and super-knock, a phenomenon attributed to the formation of detonation waves. Detonations, while wanted in few select applications, are generally to be avoided in any combustion system due to the attributed high over pressures. Hotspots, regions of higher temperature or reactivity, play a key role in understanding both autoignition and detonation initiation. Critical factors determining the thermomechanical response of a fluid to a local hotspot strongly depend on the hotspot size, temperature and temperature in the surrounding fluid, all of which influence different timescales of the ignition process. As such common modeling approaches for hotspots include rapid spatially resolved energy deposition or energy deposition through boundaries, and modeling via spatially resolved thermal stratification, such as linear temperature gradients or sinusoids. This thesis aims to improve hotspot modeling methods, by introducing a method to model a wide range of smooth temperature distributions with a small amount of parameters, and by introducing a new characterization method for the critical timescales during the initial hotspot ignition process. First a new modeling approach is introduced in order to investigate the influence of smooth temperature variations on hotspot ignition. Previous studies have already shown that temperature plateaus, modeling a hotspot center of finite size, can facilitate detonations in temperature gradients that otherwise wouldn't. Realistic temperature distributions however, will have some kind of smooth, continuous temperature distribution. A superelliptic model is introduced. Adding only 2 additional parameters compared to the plateau and gradient model, allows this new model to parametrize smooth temperature variations across wide ranges of hotspot core sizes and gradients. Various degrees of smoothness in the curved temperature profile can by achieved by varying a superelliptic exponent. By using an acoustic timescale characterization approach the results obtained could be contrasted with those obtained in previous works. It could be shown that while the intensity of the incidental pressure wave emitted at the reaction of the hotspot center is similar for plateau like and smooth temperature variations. Smooth temperature profiles on the other hand were shown to facilitate much more severe gasdynamic responses than discontinuous temperature distributions. It was further shown that hotspots considered partially inertially confined by means of an acoustic timescale characterization, can be extremely sensitive to slight variations in the superelliptic exponent and lead to direct detonation initiation. Second in order to improve the predictability of the pressure response from a local reaction hotspot, a new timescale characterization approach based on…

Subjects/Keywords: Acoustic Timescale Characterization; Autoignition; Detonation; Hotspot; Ignition; Aerospace Engineering

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Reinbacher, F. (2018). Hotspot characterization and detonation initiation in thermally stratified reactive mixtures. (Thesis). Iowa State University. Retrieved from https://lib.dr.iastate.edu/etd/16442

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Reinbacher, Fynn. “Hotspot characterization and detonation initiation in thermally stratified reactive mixtures.” 2018. Thesis, Iowa State University. Accessed April 13, 2021. https://lib.dr.iastate.edu/etd/16442.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Reinbacher, Fynn. “Hotspot characterization and detonation initiation in thermally stratified reactive mixtures.” 2018. Web. 13 Apr 2021.

Vancouver:

Reinbacher F. Hotspot characterization and detonation initiation in thermally stratified reactive mixtures. [Internet] [Thesis]. Iowa State University; 2018. [cited 2021 Apr 13]. Available from: https://lib.dr.iastate.edu/etd/16442.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Reinbacher F. Hotspot characterization and detonation initiation in thermally stratified reactive mixtures. [Thesis]. Iowa State University; 2018. Available from: https://lib.dr.iastate.edu/etd/16442

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Delft University of Technology

17. Oldenhof, E. Autoignition and flame stabilisation processes in turbulent non-premixed hot coflow flames.

Degree: 2012, Delft University of Technology

URL: http://resolver.tudelft.nl/uuid:1afe5856-eacf-42c6-b140-97ab6dafa19c ; urn:NBN:nl:ui:24-uuid:1afe5856-eacf-42c6-b140-97ab6dafa19c ; urn:NBN:nl:ui:24-uuid:1afe5856-eacf-42c6-b140-97ab6dafa19c ; http://resolver.tudelft.nl/uuid:1afe5856-eacf-42c6-b140-97ab6dafa19c

► This dissertation examines stabilisation processes in turbulent non-premixed jet flames, created by injecting gaseous fuel into a co-flowing stream of hot, low-oxygen combustion products. Being… (more)

Subjects/Keywords: autoignition; flame stabilisation; turbulent combustion

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Oldenhof, E. (2012). Autoignition and flame stabilisation processes in turbulent non-premixed hot coflow flames. (Doctoral Dissertation). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:1afe5856-eacf-42c6-b140-97ab6dafa19c ; urn:NBN:nl:ui:24-uuid:1afe5856-eacf-42c6-b140-97ab6dafa19c ; urn:NBN:nl:ui:24-uuid:1afe5856-eacf-42c6-b140-97ab6dafa19c ; http://resolver.tudelft.nl/uuid:1afe5856-eacf-42c6-b140-97ab6dafa19c

Chicago Manual of Style (16^th Edition):

Oldenhof, E. “Autoignition and flame stabilisation processes in turbulent non-premixed hot coflow flames.” 2012. Doctoral Dissertation, Delft University of Technology. Accessed April 13, 2021. http://resolver.tudelft.nl/uuid:1afe5856-eacf-42c6-b140-97ab6dafa19c ; urn:NBN:nl:ui:24-uuid:1afe5856-eacf-42c6-b140-97ab6dafa19c ; urn:NBN:nl:ui:24-uuid:1afe5856-eacf-42c6-b140-97ab6dafa19c ; http://resolver.tudelft.nl/uuid:1afe5856-eacf-42c6-b140-97ab6dafa19c.

MLA Handbook (7^th Edition):

Oldenhof, E. “Autoignition and flame stabilisation processes in turbulent non-premixed hot coflow flames.” 2012. Web. 13 Apr 2021.

Vancouver:

Oldenhof E. Autoignition and flame stabilisation processes in turbulent non-premixed hot coflow flames. [Internet] [Doctoral dissertation]. Delft University of Technology; 2012. [cited 2021 Apr 13]. Available from: http://resolver.tudelft.nl/uuid:1afe5856-eacf-42c6-b140-97ab6dafa19c ; urn:NBN:nl:ui:24-uuid:1afe5856-eacf-42c6-b140-97ab6dafa19c ; urn:NBN:nl:ui:24-uuid:1afe5856-eacf-42c6-b140-97ab6dafa19c ; http://resolver.tudelft.nl/uuid:1afe5856-eacf-42c6-b140-97ab6dafa19c.

Council of Science Editors:

Oldenhof E. Autoignition and flame stabilisation processes in turbulent non-premixed hot coflow flames. [Doctoral Dissertation]. Delft University of Technology; 2012. Available from: http://resolver.tudelft.nl/uuid:1afe5856-eacf-42c6-b140-97ab6dafa19c ; urn:NBN:nl:ui:24-uuid:1afe5856-eacf-42c6-b140-97ab6dafa19c ; urn:NBN:nl:ui:24-uuid:1afe5856-eacf-42c6-b140-97ab6dafa19c ; http://resolver.tudelft.nl/uuid:1afe5856-eacf-42c6-b140-97ab6dafa19c

Loughborough University

18. Gu, Jiayi. Chemical kinetics modelling study of naturally aspirated and boosted SI engine flame propagation and knock.

Degree: PhD, 2015, Loughborough University

URL: http://hdl.handle.net/2134/17356

► Modern spark ignition engines are downsized and boosted to meet stringent emission standards and growing customer demands on performance and fuel economy. They operate under… (more)

▼ Modern spark ignition engines are downsized and boosted to meet stringent emission standards and growing customer demands on performance and fuel economy. They operate under high intake pressures and close to their limits to engine knock. As the intake pressure is increased knock becomes the major barrier that prevents further improvement on downsized boosted spark ignition engines. It is generally accepted that knock is caused by end gas autoignition ahead of the propagating flame. The propagating flame front has been identified as one of the most influential factors that promote the occurrence of autoignition. Systematic understanding and numerical relation between the propagating flame front and the occurrence of knock are still lacking. Additionally, knock mitigation strategy that minimizes compromise on engine performance needs further researching. Therefore the objectives of the current research consist of two steps: 1). study of turbulent flame propagation in both naturally aspirated SI engine. 2) study of the relationship between flame propagation and the occurrence of engine knock for downsized and boosted SI engine. The aim of the current research is, firstly, to find out how turbulent flames propagate in naturally aspirated and boosted S.I. engines, and their interaction with the occurrence of knock; secondly, to develop a mitigation method that depresses knock intensity at higher intake pressure. Autoignition of hydrocarbon fuels as used in spark ignition engines is a complex chemical process involving large numbers of intermediate species and elementary reactions. Chemical kinetics models have been widely used to study combustion and autoignition of hydrocarbon fuels. Zero-dimensional multi-zone models provide an optimal compromise between computational accuracy and costs for engine simulation. Integration of reduced chemical kinetics model and zero-dimensional three-zone engine model is potentially a effective and efficient method to investigate the physical, chemical, thermodynamic and fluid dynamic processes involved in in-cylinder turbulence flame propagation and knock. The major contributions of the current work are made to new knowledge of quantitative relations between intake pressure, turbulent flame speed, and knock onset timing and intensity. Additionally, contributions have also been made to the development of a knock mitigation strategy that effectively depresses knock intensity under higher intake pressure while minimizes the compromise on cylinder pressure, which can be directive to future engine design.

Subjects/Keywords: 621.43; SI engines; Flame propagation; Autoignition; Chemical kinetics

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Gu, J. (2015). Chemical kinetics modelling study of naturally aspirated and boosted SI engine flame propagation and knock. (Doctoral Dissertation). Loughborough University. Retrieved from http://hdl.handle.net/2134/17356

Chicago Manual of Style (16^th Edition):

Gu, Jiayi. “Chemical kinetics modelling study of naturally aspirated and boosted SI engine flame propagation and knock.” 2015. Doctoral Dissertation, Loughborough University. Accessed April 13, 2021. http://hdl.handle.net/2134/17356.

MLA Handbook (7^th Edition):

Gu, Jiayi. “Chemical kinetics modelling study of naturally aspirated and boosted SI engine flame propagation and knock.” 2015. Web. 13 Apr 2021.

Vancouver:

Gu J. Chemical kinetics modelling study of naturally aspirated and boosted SI engine flame propagation and knock. [Internet] [Doctoral dissertation]. Loughborough University; 2015. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/2134/17356.

Council of Science Editors:

Gu J. Chemical kinetics modelling study of naturally aspirated and boosted SI engine flame propagation and knock. [Doctoral Dissertation]. Loughborough University; 2015. Available from: http://hdl.handle.net/2134/17356

University of Melbourne

19. Morganti, Kai J. A study of the knock limits of liquefied petroleum gas (LPG) in spark-ignition engines.

Degree: 2013, University of Melbourne

URL: http://hdl.handle.net/11343/38535

► A substantial increase in the use of alternative transport fuels is considered by some to be an important part of our response to climate change.… (more)

▼ A substantial increase in the use of alternative transport fuels is considered by some to be an important part of our response to climate change. Liquefied Petroleum Gas (LPG) is one such fuel that shows significant potential to improve the efficiency and greenhouse gas emissions of conventional spark-ignition engines. However, there is still some uncertainty as to the best use of LPG in spark-ignition engines. This uncertainty can largely be attributed to variations in the composition of LPG, along with the susceptibility of these different mixtures to so-called ‘autoignition’. Often, this undesirable form of combustion leads to potentially damaging rates of in-cylinder pressure rise, and therefore should be avoided. This requirement places an upper limit on the efficiency of the spark-ignition engine. This thesis therefore aims to develop a fundamental understanding of the mechanisms responsible for the autoignition of LPG mixtures under conditions relevant to spark-ignition engines. A comprehensive experimental study of the susceptibility of different LPG mixtures to autoignition is first presented. This utilises the standard ASTM Research and Motor methods for liquid fuels, which are adapted to enable the autoignition propensity of different LPGs to be quantified in terms of the so-called ‘Research and Motor octane numbers’ (RON and MON respectively). The engine experiments are then examined numerically using a multi-zone combustion model that incorporates detailed chemical kinetics. This model is calibrated and validated using empirical data, and is used to investigate the key kinetic pathways leading to the autoignition of different LPG mixtures. The work presented in this thesis first demonstrates that the linear blending of octane numbers appears to be reasonable for most LPGs. It is also shown that almost all LPGs have higher RONs than both standard and premium gasolines. Importantly, imposition of the existing MON and vapour pressure requirements specified in the Australian LPG fuel standard further increases this advantage over all gasolines. This suggests that the existing fuel standards unnecessarily restrict the composition of commercial LPGs, given the widespread use of LPG in retro-fitted gasoline vehicles at present. The modelling results indicate that an accurate model of LPG autoignition in a spark-ignition engine needs to include several key phenomena. In particular, careful modelling of the in-cylinder heat transfer and residual nitric oxide concentration should be performed, in addition to the flame propagation modelling and autoignition chemistry. When these key phenomena are included in the model, the autoignition of most LPG mixtures could be modelled to within 1.0 crank angle degree (0.28 ms) of experiment.

Subjects/Keywords: liquefied petroleum gas; LPG; octane number; RON; MON; kinetic modelling; autoignition

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Morganti, K. J. (2013). A study of the knock limits of liquefied petroleum gas (LPG) in spark-ignition engines. (Doctoral Dissertation). University of Melbourne. Retrieved from http://hdl.handle.net/11343/38535

Chicago Manual of Style (16^th Edition):

Morganti, Kai J. “A study of the knock limits of liquefied petroleum gas (LPG) in spark-ignition engines.” 2013. Doctoral Dissertation, University of Melbourne. Accessed April 13, 2021. http://hdl.handle.net/11343/38535.

MLA Handbook (7^th Edition):

Morganti, Kai J. “A study of the knock limits of liquefied petroleum gas (LPG) in spark-ignition engines.” 2013. Web. 13 Apr 2021.

Vancouver:

Morganti KJ. A study of the knock limits of liquefied petroleum gas (LPG) in spark-ignition engines. [Internet] [Doctoral dissertation]. University of Melbourne; 2013. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/11343/38535.

Council of Science Editors:

Morganti KJ. A study of the knock limits of liquefied petroleum gas (LPG) in spark-ignition engines. [Doctoral Dissertation]. University of Melbourne; 2013. Available from: http://hdl.handle.net/11343/38535

University of Waterloo

20. Buckrell, Andrew James Michael. Investigation of Mixing Models and Finite Volume Conditional Moment Closure Applied to Autoignition of Hydrogen Jets.

Degree: 2012, University of Waterloo

URL: http://hdl.handle.net/10012/6583

► In the present work, the processes of steady combustion and autoignition of hydrogen are investigated using the Conditional Moment Closure (CMC) model with a Reynolds… (more)

▼ In the present work, the processes of steady combustion and autoignition of hydrogen are investigated using the Conditional Moment Closure (CMC) model with a Reynolds Averaged Navier-Stokes (RANS) Computational Fluid Dynamics (CFD) code. A study of the effects on the flowfield of changing turbulence model constants, specifically the turbulent Schmidt number, Sct, and C epsilon 1 of the k − epsilon model, are investigated. The effects of two different mixing models are explored: the AMC model, which is commonly used in CMC implementations, and a model based on the assumption of inhomogeneous turbulence. The background equations required for implementation of the CMC model are presented, and all relevant closures are discussed. The numerical implementation of the CMC model, in addition to other techniques aimed at reducing computational expense of the CMC calculations, are provided. The CMC equation is discretised using finite volume (FV) method. The CFD and CMC calculations are fully coupled, allowing for simulations of steady flames or flame development after the occurrence of autoignition. Through testing of a steady jet flame, it is observed that the flowfield calculations follow typical k − epsilon model trends, with an overprediction of spreading and an underprediction of penetration. The CMC calculations are observed to perform well, providing good agreement with experimental measurements. Autoignition simulations are conducted for 3 different cases of turbulence constants and 7 different coflow temperatures to determine the final effect on the steady flowfield. In comparison to the standard constants, reduction of Sct results in a reduction of the centreline mixing intensity within the flowfield and a corresponding reduction of ignition length, while reducing C 1 results in an increase of centreline mixing intensity and an increase in the ignition length. All scenarios tested result in an underprediction of ignition length in comparison to experimental results; however, good agreement with the experimental trends is achieved. At low coflow temperatures, the effects of mixing intensity within the flowfield are seen to have the largest influence on ignition length, while at high coflow temperatures, the chemical source term in the CMC equation increases in magnitude, resulting in very little difference between predictions for different sets of turbulence constants. The inhomogeneous mixing model is compared using the standard turbulence constants. A reduction of ignition lengths in comparison to the AMC model is observed. In steady state simulation of the autoigniting flow, the inhomogeneous model is observed to predict both lifted flames and fully anchored flames, depending on coflow temperature.

Subjects/Keywords: CFD; CMC; turbulent combustion; autoignition; hydrogen; computational fluid dynamics

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Buckrell, A. J. M. (2012). Investigation of Mixing Models and Finite Volume Conditional Moment Closure Applied to Autoignition of Hydrogen Jets. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/6583

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Buckrell, Andrew James Michael. “Investigation of Mixing Models and Finite Volume Conditional Moment Closure Applied to Autoignition of Hydrogen Jets.” 2012. Thesis, University of Waterloo. Accessed April 13, 2021. http://hdl.handle.net/10012/6583.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Buckrell, Andrew James Michael. “Investigation of Mixing Models and Finite Volume Conditional Moment Closure Applied to Autoignition of Hydrogen Jets.” 2012. Web. 13 Apr 2021.

Vancouver:

Buckrell AJM. Investigation of Mixing Models and Finite Volume Conditional Moment Closure Applied to Autoignition of Hydrogen Jets. [Internet] [Thesis]. University of Waterloo; 2012. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/10012/6583.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Buckrell AJM. Investigation of Mixing Models and Finite Volume Conditional Moment Closure Applied to Autoignition of Hydrogen Jets. [Thesis]. University of Waterloo; 2012. Available from: http://hdl.handle.net/10012/6583

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of British Columbia

21. Wu, Ning. Autoignition and emission characteristics of gaseous fuel direct-injection compression-ignition combustion.

Degree: PhD, Mechanical Engineering, 2007, University of British Columbia

URL: http://hdl.handle.net/2429/357

► Heavy-duty natural gas engines offer air pollution and energy diversity benefits. However, current homogeneous-charge lean-burn engines suffer from impaired efficiency and high unburned fuel emissions.… (more)

▼ Heavy-duty natural gas engines offer air pollution and energy diversity benefits. However, current homogeneous-charge lean-burn engines suffer from impaired efficiency and high unburned fuel emissions. Natural gas direct-injection engines offer the potential of diesel-like efficiencies, but require further research. To improve understanding of the autoignition and emission characteristics of natural gas direct-injection compression-ignition combustion, the effects of key operating parameters (including injection pressure, injection duration, and pre-combustion temperature) and gaseous fuel composition(including the effects of ethane, hydrogen and nitrogen addition) were studied. An experimental investigation was carried out on a shock tube facility. Ignition delay, ignition kernel location, and NOx emissions were measured. The results indicated that the addition of ethane to the fuel resulted in a decrease in ignition delay and a significant increase in NOx emissions. The addition of hydrogen to the fuel resulted in a decrease in ignition delay and a significant decrease in NOx emissions. Diluting the fuel with nitrogen resulted in an increase in ignition delay and a significant decrease in NOx emissions. Increasing pre-combustion temperature resulted in a significant reduction in ignition delay, and a significant increase in NOx emissions. Modest increase in injection pressure reduced the ignition delay; increasing injection pressure resulted in higher NOx emissions. The effects of ethane, hydrogen, and nitrogen addition on the ignition delay of methane were also successfully predicted by FlameMaster simulation. OH radical distribution in the flame was visualized utilizing Planar Laser Induced Fluorescence (PLIF). Single-shot OH-PLIF images revealed the stochastic nature of the autoignition process of non-premixed methane jets. Examination of the convergence of the ensemble-averaged OH-PLIF images showed that increasing the number of repeat experiments was the most effective way to achieve a more converged result. A combustion model, which incorporated the Conditional Source-term Estimation(CSE) method for the closure of the chemical source term and the Trajectory Generated Low-Dimensional Manifold (TGLDM) method for the reduction of detailed chemistry, was applied to predict the OH distribution in a combusting non-premixed methane jet. The model failed to predict the OH distribution as indicated by the ensemble-averaged OH-PLIF images, since it cannot account for fluctuations in either turbulence or chemistry.

Subjects/Keywords: autoignition; non-premixed; methane; jet

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Wu, N. (2007). Autoignition and emission characteristics of gaseous fuel direct-injection compression-ignition combustion. (Doctoral Dissertation). University of British Columbia. Retrieved from http://hdl.handle.net/2429/357

Chicago Manual of Style (16^th Edition):

Wu, Ning. “Autoignition and emission characteristics of gaseous fuel direct-injection compression-ignition combustion.” 2007. Doctoral Dissertation, University of British Columbia. Accessed April 13, 2021. http://hdl.handle.net/2429/357.

MLA Handbook (7^th Edition):

Wu, Ning. “Autoignition and emission characteristics of gaseous fuel direct-injection compression-ignition combustion.” 2007. Web. 13 Apr 2021.

Vancouver:

Wu N. Autoignition and emission characteristics of gaseous fuel direct-injection compression-ignition combustion. [Internet] [Doctoral dissertation]. University of British Columbia; 2007. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/2429/357.

Council of Science Editors:

Wu N. Autoignition and emission characteristics of gaseous fuel direct-injection compression-ignition combustion. [Doctoral Dissertation]. University of British Columbia; 2007. Available from: http://hdl.handle.net/2429/357

22. Rose, Evan Noah. Autoignition Dynamics and Combustion of n-Dodecane Dropletsunder Transcritical Conditions.

Degree: MSs, EMC - Mechanical Engineering, 2019, Case Western Reserve University School of Graduate Studies

URL: http://rave.ohiolink.edu/etdc/view?acc_num=case1554288408975334

► Understanding the spontaneous ignition and burning behavior of liquid fuels is criticalto improving the performance of modern combustion devices. This work examinesthe effects of varying… (more)

Subjects/Keywords: Mechanical Engineering; combustion; autoignition; ignition; droplet; NTC; two-stage ignition; dodecane

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Rose, E. N. (2019). Autoignition Dynamics and Combustion of n-Dodecane Dropletsunder Transcritical Conditions. (Masters Thesis). Case Western Reserve University School of Graduate Studies. Retrieved from http://rave.ohiolink.edu/etdc/view?acc_num=case1554288408975334

Chicago Manual of Style (16^th Edition):

Rose, Evan Noah. “Autoignition Dynamics and Combustion of n-Dodecane Dropletsunder Transcritical Conditions.” 2019. Masters Thesis, Case Western Reserve University School of Graduate Studies. Accessed April 13, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case1554288408975334.

MLA Handbook (7^th Edition):

Rose, Evan Noah. “Autoignition Dynamics and Combustion of n-Dodecane Dropletsunder Transcritical Conditions.” 2019. Web. 13 Apr 2021.

Vancouver:

Rose EN. Autoignition Dynamics and Combustion of n-Dodecane Dropletsunder Transcritical Conditions. [Internet] [Masters thesis]. Case Western Reserve University School of Graduate Studies; 2019. [cited 2021 Apr 13]. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=case1554288408975334.

Council of Science Editors:

Rose EN. Autoignition Dynamics and Combustion of n-Dodecane Dropletsunder Transcritical Conditions. [Masters Thesis]. Case Western Reserve University School of Graduate Studies; 2019. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=case1554288408975334

Clemson University

23. Robertson, Dennis. Combustion Phasing Modeling for Control of Spark-Assisted Compression Ignition Engines.

Degree: PhD, Automotive Engineering, 2020, Clemson University

URL: https://tigerprints.clemson.edu/all_dissertations/2732

► Substantial fuel economy improvements for light-duty automotive engines demand novel combustion strategies. Low temperature combustion (LTC) demonstrates potential for significant fuel efficiency improvement; however,… (more)

▼ Substantial fuel economy improvements for light-duty automotive engines demand novel combustion strategies. Low temperature combustion (LTC) demonstrates potential for significant fuel efficiency improvement; however, control complexity is an impediment for real-world transient operation. Spark-assisted compression ignition (SACI) is an LTC strategy that applies a deflagration flame to generate sufficient energy to trigger autoignition in the remaining charge. For other LTC strategies, control of autoignition timing is difficult as there is no direct actuator for combustion phasing. SACI addresses this challenge by using a spark plug to initiate a flame that then triggers autoignition in a significant portion of the charge. The flame propagation phase limits the rate of cylinder pressure increase, while autoignition rapidly completes combustion. High dilution is generally required to maintain production-feasible reaction rates. This high dilution, however, increases the likelihood of flame quench, and therefore potential misfires. Mitigating these competing constraints requires careful mixture preparation strategies for SACI to be feasible in production. Operating a practical engine within this restrictive regime is a key modeling and control challenge. Current models are not sufficient for control-oriented work such as calibration optimization, transient control strategy development, and real-time control. To resolve the modeling challenge, a fast-running cylinder model is developed and presented in this work. It comprises of five bulk gas states and a fuel stratification model comprising of ten equal-mass zones within the cylinder. The zones are quasi-dimensional, and their state varies with crank angle to capture the effect of fuel spray and mixing. For each zone, combustion submodels predict flame propagation burn duration, autoignition phasing, and the concentration of oxides of nitrogen. During the development of the combustion submodels, both physics-based and data-driven techniques are considered. However, the best balance between accuracy and computational expense leads to the nearly exclusive selection of data-driven techniques. The data-driven models are artificial neural networks (ANNs), trained to an experimentally-validated one-dimensional (1D) engine reference model. The simplified model matches the reference 1D engine model with an R2 value of 70‒96% for key combustion parameters. The model requires 0.8 seconds to perform a single case, a 99.6% reduction from the reference 1D engine model. The reduced model simulation time enables rapid exploration of the control space. Over 250,000 cases are evaluated across the entire range of actuator positions. From these results, a transient-capable calibration is formulated. To evaluate the strength of the steady-state calibration, it is operated over a tip-in and tip-out. The response to the transients required little adjustment, suggesting the steady-state calibration is robust. The model also demonstrates the capability to adapt in-cylinder state and spark… Advisors/Committee Members: Robert Prucka, Zoran Filipi, Benjamin Lawler, Jiangfeng Zhang.

Subjects/Keywords: Autoignition; Combustion; Flame Propagation; Machine Learning; Modeling; SACI

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Robertson, D. (2020). Combustion Phasing Modeling for Control of Spark-Assisted Compression Ignition Engines. (Doctoral Dissertation). Clemson University. Retrieved from https://tigerprints.clemson.edu/all_dissertations/2732

Chicago Manual of Style (16^th Edition):

Robertson, Dennis. “Combustion Phasing Modeling for Control of Spark-Assisted Compression Ignition Engines.” 2020. Doctoral Dissertation, Clemson University. Accessed April 13, 2021. https://tigerprints.clemson.edu/all_dissertations/2732.

MLA Handbook (7^th Edition):

Robertson, Dennis. “Combustion Phasing Modeling for Control of Spark-Assisted Compression Ignition Engines.” 2020. Web. 13 Apr 2021.

Vancouver:

Robertson D. Combustion Phasing Modeling for Control of Spark-Assisted Compression Ignition Engines. [Internet] [Doctoral dissertation]. Clemson University; 2020. [cited 2021 Apr 13]. Available from: https://tigerprints.clemson.edu/all_dissertations/2732.

Council of Science Editors:

Robertson D. Combustion Phasing Modeling for Control of Spark-Assisted Compression Ignition Engines. [Doctoral Dissertation]. Clemson University; 2020. Available from: https://tigerprints.clemson.edu/all_dissertations/2732

University of California – Berkeley

24. North, Andrew. Experimental Investigations of Partially Premixed Hydrogen Combustion in Gas Turbine Environments.

Degree: Applied Science & Technology, 2013, University of California – Berkeley

URL: http://www.escholarship.org/uc/item/2v3007n3

► The carbon dioxide emission prevention advantage of generating power with high hydrogen content fuels using gas turbines motivates an improved understanding of the ignition behavior… (more)

▼ The carbon dioxide emission prevention advantage of generating power with high hydrogen content fuels using gas turbines motivates an improved understanding of the ignition behavior of hydrogen in premixed and partially premixed environments. Hydrogen rich fueled flame stability is sensitive to operating conditions, including environment pressure, temperature, and jet velocity. Furthermore, when premixed or partially premixed operation is desired for nitric oxide emissions reduction, a diluent, such as nitrogen, is often added in allowing fuel/air mixing prior to combustion. Thus, the concentration of the diluent added is an additional independent variable on which flame stability dependence understanding is needed. The focus of this research is on characterizing the dependence of hydrogen jet flame stability on environment temperature, jet velocity, diluent concentration, and pressure by determining the dependence of the liftoff height of lifted flames on these 4 independent parameters. Nitrogen is used as the diluent due to its availability and effectiveness in promoting liftoff. Experiments are first conducted at atmospheric pressure in scoping subsequent research where the additional parameter of pressure is added. The stability and liftoff characteristics of a nitrogen diluted hydrogen jet flame at atmospheric pressure in a vitiated co-flow are investigated experimentally and numerically with particular attention focused on regimes where multiple stabilization mechanisms are active. Information gleaned from this research is instrumental for informing modeling approaches in flame transition situations when both autoignition and flame propagation influence combustion characteristics. Stability regime diagrams which outline the conditions under which the flame is attached, lifted, blown-out, and unsteady are experimentally developed and explored. The stability of the flame is investigated with a 1D Reynolds Averaged Navier Stokes parabolic numerical model which shows that under certain conditions, local turbulent flame speeds exceed the local velocity for the production of stable lifted hydrogen flames. These modeling results suggest that the dominant flame stabilization mechanism is flame propagation, and likely tribrachial flame propagation, consistent with the conclusions of prior studies for jet flames issuing into ambient environments such as the research of Muñiz and Mungal (1997). The lifted regime is further characterized at atmospheric pressure in determining liftoff height dependence on co-flow temperature, jet velocity, and nitrogen dilution. A strong sensitivity of liftoff height to co-flow temperature, jet velocity, and nitrogen dilution is observed. The numerical model results trend well with the experimentally developed stability regime diagrams. Liftoff heights predicted by Kalghatgi's correlation are unable to capture the effects of nitrogen dilution on liftoff height for the heated co-flow cases. A uniquely formulated Damköhler number was therefore developed which acceptably captures the…

Subjects/Keywords: Alternative energy; Mechanical engineering; Autoignition; Flame Propagation; Hydrogen; Jet Flames; Lifted Flames; Turbulent Combustion

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

North, A. (2013). Experimental Investigations of Partially Premixed Hydrogen Combustion in Gas Turbine Environments. (Thesis). University of California – Berkeley. Retrieved from http://www.escholarship.org/uc/item/2v3007n3

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

North, Andrew. “Experimental Investigations of Partially Premixed Hydrogen Combustion in Gas Turbine Environments.” 2013. Thesis, University of California – Berkeley. Accessed April 13, 2021. http://www.escholarship.org/uc/item/2v3007n3.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

North, Andrew. “Experimental Investigations of Partially Premixed Hydrogen Combustion in Gas Turbine Environments.” 2013. Web. 13 Apr 2021.

Vancouver:

North A. Experimental Investigations of Partially Premixed Hydrogen Combustion in Gas Turbine Environments. [Internet] [Thesis]. University of California – Berkeley; 2013. [cited 2021 Apr 13]. Available from: http://www.escholarship.org/uc/item/2v3007n3.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

North A. Experimental Investigations of Partially Premixed Hydrogen Combustion in Gas Turbine Environments. [Thesis]. University of California – Berkeley; 2013. Available from: http://www.escholarship.org/uc/item/2v3007n3

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

25. Kang, Dongil. Impacts of Fuel Chemical Structure and Composition on Fundamental Ignition Behavior and Autoignition Chemistry in a Motored Engine.

Degree: PhD, Chemical Engineering, 2016, University of Michigan

URL: http://hdl.handle.net/2027.42/133374

► The autoignition characteristics of individual hydrocarbon species studied in motored engine can provide a better understanding of the autoignition process and complex fuels for homogeneous… (more)

▼ The autoignition characteristics of individual hydrocarbon species studied in motored engine can provide a better understanding of the autoignition process and complex fuels for homogeneous spark and compression ignition engines, whether the interest is understanding and preventing knock or controlling autoignition. In both instances, there is a critical need to comprehend how fuel molecular structure either retards or promotes autoignition reactivity. This understanding ultimately contributes to the development of kinetic mechanisms, which are needed for simulation of reacting flows and autoignition processes. For this reason, the dissertation discusses autoignition data on i) three pentane isomers (n-pentane, neo-pentane and iso-pentane), ii) ethyl-cycloahexane and its two isomers (1,3-dimethyl-cyclohexane and 1,2-dimethyl-cyclohexane), and iii) diisobutylene in primary reference fuels. looking for their chemical structural impacts on the ignition process. Particularly for exploring the low and intermediate temperature regions, the motored variable compression ratio engine, developed from a Cooperative Fuel Research (CFR) Octane Rating engine, provided a good platform. Analyses of the stable intermediates in the CFR engine exhaust at various end of compression pressures and temperatures can help to identify reaction pathways through which different compounds prefer to autoignite. The approach of those studies is to conduct a systematic investigation of the autoignition, which can provide useful input for qualitative and semi-quantitative validation of kinetic mechanisms for oxidation of target chemical compounds. Finally, the dissertation is further extended to an experimental validation of jet aviation fuel surrogates, potentially emulating a series of physical and chemical ignition processes in diesel engines, with an emphasis on the needs for detailed auto-ignition characteristics of various individual hydrocarbon species. Advisors/Committee Members: Boehman, Andre L (committee member), Savage, Phillip E (committee member), Violi, Angela (committee member), Schwank, Johannes W (committee member).

Subjects/Keywords: Autoignition process; CFR octane rating engine; hydrocarbon oxidation; Chemical Engineering; Mechanical Engineering; Engineering

15 more images…

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Kang, D. (2016). Impacts of Fuel Chemical Structure and Composition on Fundamental Ignition Behavior and Autoignition Chemistry in a Motored Engine. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/133374

Chicago Manual of Style (16^th Edition):

Kang, Dongil. “Impacts of Fuel Chemical Structure and Composition on Fundamental Ignition Behavior and Autoignition Chemistry in a Motored Engine.” 2016. Doctoral Dissertation, University of Michigan. Accessed April 13, 2021. http://hdl.handle.net/2027.42/133374.

MLA Handbook (7^th Edition):

Kang, Dongil. “Impacts of Fuel Chemical Structure and Composition on Fundamental Ignition Behavior and Autoignition Chemistry in a Motored Engine.” 2016. Web. 13 Apr 2021.

Vancouver:

Kang D. Impacts of Fuel Chemical Structure and Composition on Fundamental Ignition Behavior and Autoignition Chemistry in a Motored Engine. [Internet] [Doctoral dissertation]. University of Michigan; 2016. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/2027.42/133374.

Council of Science Editors:

Kang D. Impacts of Fuel Chemical Structure and Composition on Fundamental Ignition Behavior and Autoignition Chemistry in a Motored Engine. [Doctoral Dissertation]. University of Michigan; 2016. Available from: http://hdl.handle.net/2027.42/133374

Penn State University

26. Kalaskar, Vickey Baliram. Ignition Behavior of Gasolines and Surrogate Fuels in Low Temperature Combustion Strategies.

Degree: 2015, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/25975

► This dissertation discusses the results from three different studies aimed at understanding the importance of fuel chemical structure during low temperature combustion (LTC) strategies, like… (more)

▼ This dissertation discusses the results from three different studies aimed at understanding the importance of fuel chemical structure during low temperature combustion (LTC) strategies, like homogeneous charge compression ignition (HCCI) and partially premixed combustion (PPC) employed in internal combustion (IC) engines wherein the focus is on high octane fuels. Boosted intake air operation combined with exhaust gas recirculation, internal as well as external, has become a standard path for expanding the load limits of IC engines employing LTC strategies mentioned above as well as conventional diesel and spark ignition (SI) engines. However, the effects of fuel compositional variation have not been fully explored. The first study focusses on three different fuels, where each of them were evaluated using a single cylinder boosted HCCI engine using negative valve overlap. The three fuels investigated were: a regular grade gasoline (RON = 90.2), 30% ethanol-gasoline blend (E30, RON = 100.3), and 24% iso-butanol-gasoline blend (IB24, RON = 96.6). Detailed sweeps of intake manifold pressure (atmospheric to 250 kPaa), EGR (0 – 25% EGR), and injection timing were conducted to identify fuel-specific effects. While significant fuel compositional differences existed, the results showed that all these fuels achieved comparable operation with minor changes in operational conditions. Further, it was shown that the available enthalpy from the exhaust would not be sufficient to satisfy the boost requirements at higher load operation by doing an analysis of the required turbocharger efficiency. While the first study concentrated on load expansion of HCCI, it is important to mention that controlling LTC strategies is difficult under low load or idle operating conditions. To ensure stable operation, fuel injection in the negative valve overlap (NVO) is used as one of method of achieving combustion control. However the combustion chemistry under high temperature and fuel rich conditions that exist during the NVO have not been previously explored. The second study focused on examining the products of fuel rich chemistry as a result of fuel injection in the NVO. In this study, a unique six stroke cycle was used to segregate the exhaust from the NVO and to study the chemistry of the range of fuels injected during NVO under low oxygen conditions. The fuels investigated were methanol, ethanol, iso-butanol, and iso-octane. It was observed that the products of reactions under NVO conditions were highly dependent on the injected fuel’s structure with iso-octane producing less than 1.5% hydrogen and methanol producing more than 8%. However a weak dependence was observed on NVO duration and initial temperature, indicating that NVO reforming was kinetically limited. Finally, the experimental trends were compared with CHEMKIN (single zone, 0-D model) predictions using multiple kinetic mechanism that were readily available through literature. Due to the simplicity of the model and inadequate information on the fuel injection process, the… Advisors/Committee Members: Andre Louis Boehman, Dissertation Advisor/Co-Advisor, Randy Vander Wal, Dissertation Advisor/Co-Advisor, Chunshan Song, Committee Member, Daniel Connell Haworth, Committee Member, James Szybist, Special Member.

Subjects/Keywords: Autoignition; Combustion; Compression ignition; Negative valve overlap; Ignition behavior; LTC; HCCI; PPC

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Kalaskar, V. B. (2015). Ignition Behavior of Gasolines and Surrogate Fuels in Low Temperature Combustion Strategies. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/25975

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Kalaskar, Vickey Baliram. “Ignition Behavior of Gasolines and Surrogate Fuels in Low Temperature Combustion Strategies.” 2015. Thesis, Penn State University. Accessed April 13, 2021. https://submit-etda.libraries.psu.edu/catalog/25975.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Kalaskar, Vickey Baliram. “Ignition Behavior of Gasolines and Surrogate Fuels in Low Temperature Combustion Strategies.” 2015. Web. 13 Apr 2021.

Vancouver:

Kalaskar VB. Ignition Behavior of Gasolines and Surrogate Fuels in Low Temperature Combustion Strategies. [Internet] [Thesis]. Penn State University; 2015. [cited 2021 Apr 13]. Available from: https://submit-etda.libraries.psu.edu/catalog/25975.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Kalaskar VB. Ignition Behavior of Gasolines and Surrogate Fuels in Low Temperature Combustion Strategies. [Thesis]. Penn State University; 2015. Available from: https://submit-etda.libraries.psu.edu/catalog/25975

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Wayne State University

27. Zheng, Ziliang. Effect Of Cetane Number And Volatility On Autoignition And Combustion Of Alternative Fuels And Their Surrogates.

Degree: PhD, Mechanical Engineering, 2014, Wayne State University

URL: https://digitalcommons.wayne.edu/oa_dissertations/947

► Diesel engine has become a popular choice for trucks, trains, boats, and most other heavy-duty applications. The inherent benefits of diesel engine are high… (more)

Subjects/Keywords: alternative fuels; autoignition; CFD simulation; combustion; ignition quality tester; surrogate; Mechanical Engineering

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Zheng, Z. (2014). Effect Of Cetane Number And Volatility On Autoignition And Combustion Of Alternative Fuels And Their Surrogates. (Doctoral Dissertation). Wayne State University. Retrieved from https://digitalcommons.wayne.edu/oa_dissertations/947

Chicago Manual of Style (16^th Edition):

Zheng, Ziliang. “Effect Of Cetane Number And Volatility On Autoignition And Combustion Of Alternative Fuels And Their Surrogates.” 2014. Doctoral Dissertation, Wayne State University. Accessed April 13, 2021. https://digitalcommons.wayne.edu/oa_dissertations/947.

MLA Handbook (7^th Edition):

Zheng, Ziliang. “Effect Of Cetane Number And Volatility On Autoignition And Combustion Of Alternative Fuels And Their Surrogates.” 2014. Web. 13 Apr 2021.

Vancouver:

Zheng Z. Effect Of Cetane Number And Volatility On Autoignition And Combustion Of Alternative Fuels And Their Surrogates. [Internet] [Doctoral dissertation]. Wayne State University; 2014. [cited 2021 Apr 13]. Available from: https://digitalcommons.wayne.edu/oa_dissertations/947.

Council of Science Editors:

Zheng Z. Effect Of Cetane Number And Volatility On Autoignition And Combustion Of Alternative Fuels And Their Surrogates. [Doctoral Dissertation]. Wayne State University; 2014. Available from: https://digitalcommons.wayne.edu/oa_dissertations/947

28. Johnson, Kali. Investigation on the Influence of Organic Polymer Additives on n-Heptane Autoignition.

Degree: M.S.M.E., Mechanical Engineering, 2016, University of Minnesota

URL: http://hdl.handle.net/11299/185086

► Increasing compression ratio of spark ignition (SI) engines can improve fuel efficiency; however, engines with higher compression ratios are more likely to experience knock or… (more)

▼ Increasing compression ratio of spark ignition (SI) engines can improve fuel efficiency; however, engines with higher compression ratios are more likely to experience knock or pre-ignition, a potentially damaging phenomenon. One method to suppress knock is to use fuel additives; however, traditional organometallic additives like tetraethyl lead, while effective create toxic lead oxide nanoparticles. This study examined the hypothesis that organic polymer nanoparticles could be used as environmentally benign anti-knock additives by scavenging gas-phase radicals responsible for autoignition and then be consumed in the eventual combustion event. The organic polymer polycyclohexylethylene (PCHE) in n-heptane, a single component gasoline fuel surrogate, was experimentally investigated. To imitate fuel atomization and vaporization in a SI engine, a pneumatic atomizer was used to generate PCHE nanoparticles entrained in gaseous n-heptane and air mixtures. Liquid phase concentrations of 0.01, 0.05 and 0.10 percent by weight PCHE in n-heptane were compared to n-heptane with no additive. Particle number as a function of diameter produced by the atomization process was quantified for each solution. In addition, the thermal stability and autoignition characteristics of the additive-doped fuels were examined using a laminar flow reactor. Results of the study showed that the pneumatic atomization process was able to successfully produce solid PCHE nanoparticles. Number of particles increased with additive concentration indicating that the PCHE was miscible in liquid n-heptane. Thermal degradation of the PCHE nanoparticles began when the reactor temperature reached approximately 775 ˚C. Although droplet evaporation produced PCHE nanoparticles in significant concentrations, the reactive experiments showed no difference in autoignition temperature between the additive-containing fuels and n-heptane alone. Although the central hypothesis of the study was not proven for PCHE particles, the same experimental design can be tested with other organic polymers.

Subjects/Keywords: Autoignition; Fuel Additive; Organic Polymers

…List of Figures Figure 1: Autoignition sites in the end gas along the cylinder wall (… …the Autoignition Temperature Experiments… …42 Figure 13: Thermocouple placement inside Furnace for Autoignition Experiments ....... 50… …70 Figure 25: dT/dt versus Outlet Temperature for four Autoignition Trials… …73 Figure 27: Total Concentration vs. Time for Four Autoignition Experiment Trials…

10 more images…

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Johnson, K. (2016). Investigation on the Influence of Organic Polymer Additives on n-Heptane Autoignition. (Masters Thesis). University of Minnesota. Retrieved from http://hdl.handle.net/11299/185086

Chicago Manual of Style (16^th Edition):

Johnson, Kali. “Investigation on the Influence of Organic Polymer Additives on n-Heptane Autoignition.” 2016. Masters Thesis, University of Minnesota. Accessed April 13, 2021. http://hdl.handle.net/11299/185086.

MLA Handbook (7^th Edition):

Johnson, Kali. “Investigation on the Influence of Organic Polymer Additives on n-Heptane Autoignition.” 2016. Web. 13 Apr 2021.

Vancouver:

Johnson K. Investigation on the Influence of Organic Polymer Additives on n-Heptane Autoignition. [Internet] [Masters thesis]. University of Minnesota; 2016. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/11299/185086.

Council of Science Editors:

Johnson K. Investigation on the Influence of Organic Polymer Additives on n-Heptane Autoignition. [Masters Thesis]. University of Minnesota; 2016. Available from: http://hdl.handle.net/11299/185086

University of Maryland

29. Fuller, Casey Charles. INVESTIGATION OF JP-8 AUTOIGNITION UNDER VITIATED COMBUSTION CONDITIONS.

Degree: Mechanical Engineering, 2011, University of Maryland

URL: http://hdl.handle.net/1903/11583

► Limited data on jet fuel ignition and oxidation at low-O2, vitiated conditions has hindered the validation of kinetic models for combustion under such conditions. In… (more)

Subjects/Keywords: Mechanical Engineering; Autoignition; Flow Reactor; Jet Fuel; Low Pressure; Nitric Oxide; Vitiated Air

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Fuller, C. C. (2011). INVESTIGATION OF JP-8 AUTOIGNITION UNDER VITIATED COMBUSTION CONDITIONS. (Thesis). University of Maryland. Retrieved from http://hdl.handle.net/1903/11583

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Fuller, Casey Charles. “INVESTIGATION OF JP-8 AUTOIGNITION UNDER VITIATED COMBUSTION CONDITIONS.” 2011. Thesis, University of Maryland. Accessed April 13, 2021. http://hdl.handle.net/1903/11583.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Fuller, Casey Charles. “INVESTIGATION OF JP-8 AUTOIGNITION UNDER VITIATED COMBUSTION CONDITIONS.” 2011. Web. 13 Apr 2021.

Vancouver:

Fuller CC. INVESTIGATION OF JP-8 AUTOIGNITION UNDER VITIATED COMBUSTION CONDITIONS. [Internet] [Thesis]. University of Maryland; 2011. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/1903/11583.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Fuller CC. INVESTIGATION OF JP-8 AUTOIGNITION UNDER VITIATED COMBUSTION CONDITIONS. [Thesis]. University of Maryland; 2011. Available from: http://hdl.handle.net/1903/11583

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

30. Grib, Stephen William. LAMINAR AND TURBULENT STUDY OF COMBUSTION IN STRATIFIED ENVIRONMENTS USING LASER BASED MEASUREMENTS.

Degree: 2018, University of Kentucky

URL: https://uknowledge.uky.edu/me_etds/117

► Practical gas turbine engine combustors create extremely non-uniform flowfields, which are highly stratified making it imperative that similar environments are well understood. Laser diagnostics were… (more)

▼ Practical gas turbine engine combustors create extremely non-uniform flowfields, which are highly stratified making it imperative that similar environments are well understood. Laser diagnostics were utilized in a variety of stratified environments, which led to temperature or chemical composition gradients, to better understand autoignition, extinction, and flame stability behavior. This work ranged from laminar and steady flames to turbulent flame studies in which time resolved measurements were used. Edge flames, formed in the presence of species stratification, were studied by first developing a simple measurement technique which is capable of estimating an important quantity for edge flames, the advective heat flux, using only velocity measurements. Both hydroxyl planar laser induced fluorescence (OH PLIF) and particle image velocimetry (PIV) were used along with numerical simulations in the development of this technique. Interacting triple flames were also created in a laboratory scale burner producing a laminar and steady flowfield with symmetric equivalence ratio gradients. Studies were conducted in order to characterize and model the propagation speed as a function of the flame base curvature and separation distance between the neighboring flames. OH PLIF, PIV and Rayleigh scattering measurements were used in order to characterize the propagation speed. A model was developed which is capable of accurately representing the propagation speed for three different fuels. Negative edge flames were first studied by developing a one-dimensional model capable of reproducing the energy equation along the stoichiometric line, which was dependent on different boundary conditions. Unsteady and laminar negative edge flames were also simulated with periodic boundary conditions in order to assess the difference between the steady and unsteady cases. The diffusive heat loss was unbalanced with the chemical heat release and advective heat flux energy gain terms which led to the flame proceeding and receding. The temporal derivative balanced the energy equation, but also aided in the understanding of negative edge flame speeds. Turbulent negative edge flame velocities were measured for extinguishing flames in a separate experiment as a function of the bulk advective heat flux through the edge and turbulence level. A burner was designed and built for this study which created statistically stationary negative edge flames. The edge velocity was dependent on both the bulk advective heat flux and turbulence levels. The negative edge flame velocities were obtained with high speed stereo-view chemiluminescence and two dimensional PIV measurements. Autoignition stabilization was studied in the presence of both temperature and species stratification, using a simple laminar flowfield. OH and CH2O PLIF measurements showed autoignition characteristics ahead of the flame base. Numerical chemical and flow simulations also revealed lower temperature chemistry characteristics ahead of the flame base leading to the conclusion of lower…

Subjects/Keywords: Laser Diagnostics; Edge Flames; Autoignition; Flame Stabilization; Extinction; Heat Transfer, Combustion; Propulsion and Power

10 more images…

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Grib, S. W. (2018). LAMINAR AND TURBULENT STUDY OF COMBUSTION IN STRATIFIED ENVIRONMENTS USING LASER BASED MEASUREMENTS. (Doctoral Dissertation). University of Kentucky. Retrieved from https://uknowledge.uky.edu/me_etds/117

Chicago Manual of Style (16^th Edition):

Grib, Stephen William. “LAMINAR AND TURBULENT STUDY OF COMBUSTION IN STRATIFIED ENVIRONMENTS USING LASER BASED MEASUREMENTS.” 2018. Doctoral Dissertation, University of Kentucky. Accessed April 13, 2021. https://uknowledge.uky.edu/me_etds/117.

MLA Handbook (7^th Edition):

Grib, Stephen William. “LAMINAR AND TURBULENT STUDY OF COMBUSTION IN STRATIFIED ENVIRONMENTS USING LASER BASED MEASUREMENTS.” 2018. Web. 13 Apr 2021.

Vancouver:

Grib SW. LAMINAR AND TURBULENT STUDY OF COMBUSTION IN STRATIFIED ENVIRONMENTS USING LASER BASED MEASUREMENTS. [Internet] [Doctoral dissertation]. University of Kentucky; 2018. [cited 2021 Apr 13]. Available from: https://uknowledge.uky.edu/me_etds/117.

Council of Science Editors:

Grib SW. LAMINAR AND TURBULENT STUDY OF COMBUSTION IN STRATIFIED ENVIRONMENTS USING LASER BASED MEASUREMENTS. [Doctoral Dissertation]. University of Kentucky; 2018. Available from: https://uknowledge.uky.edu/me_etds/117

Open Access Theses and Dissertations