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University of Illinois – Urbana-Champaign
1.
Shields, Benjamin Thomas.
Stationary edge flames in a wedge with hydrodynamic variable-density interaction.
Degree: PhD, Theoretical & Applied Mechans, 2020, University of Illinois – Urbana-Champaign
URL: http://hdl.handle.net/2142/108502 
► Edge flames are a canonical two-dimensional flame structure appearing in more complicated combustion problems, such as lifted jet flames and in the dynamics of the…
(more)
▼ Edge flames are a canonical two-dimensional
flame structure appearing in more complicated combustion problems, such as lifted jet flames and in the dynamics of the growth and repair of
flame holes in nonpremixed turbulent combustion. Typical theoretical configurations to study
edge flames are unable to evaluate retreating
edge flames with strong hydrodynamic-coupling. A new computational configuration is introduced which places the
edge flame in a wedge-shaped counterflow with a mass sink, providing control over the position of the
edge flame, and allowing access to stationary, hydrodynamically-coupled retreating flames (at high strain). This framework is first used to evaluate
edge flames using a simple global one-step chemistry model and Fickian transport. This simple model is used to characterize the behavior of the resulting
edge flames, including the relationship between
flame speed and transverse strain rate and response to Lewis number variations. The details of the computational method will be discussed, including the underlying finite element method, the generation of boundary data, and the continuation of the
flame through regions of varying transverse strain. This configuration is then applied to detailed ethylene-air combustion using a skeletal reduction of the USC Mech II combustion reaction model and a detailed transport model. The details of the ethylene-air
edge flame are discussed, and comparisons are made between stoichiometric, fuel-lean, and fuel-rich compositions. Novel results characterizing the dilatation and vorticity near the
flame front are provided, data which are necessary for the construction of potential flow approximations of hydrodynamically-coupled
edge flames.
Advisors/Committee Members: Freund, Jonathan B (advisor), Pantano, Carlos (advisor), Freund, Jonathan B (Committee Chair), Fischer, Paul (committee member), Panesi, Marco (committee member).
Subjects/Keywords: Combustion; Edge Flame; Ethylene; Nonpremixed
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APA (6th Edition):
Shields, B. T. (2020). Stationary edge flames in a wedge with hydrodynamic variable-density interaction. (Doctoral Dissertation). University of Illinois – Urbana-Champaign. Retrieved from http://hdl.handle.net/2142/108502
Chicago Manual of Style (16th Edition):
Shields, Benjamin Thomas. “Stationary edge flames in a wedge with hydrodynamic variable-density interaction.” 2020. Doctoral Dissertation, University of Illinois – Urbana-Champaign. Accessed April 17, 2021.
http://hdl.handle.net/2142/108502.
MLA Handbook (7th Edition):
Shields, Benjamin Thomas. “Stationary edge flames in a wedge with hydrodynamic variable-density interaction.” 2020. Web. 17 Apr 2021.
Vancouver:
Shields BT. Stationary edge flames in a wedge with hydrodynamic variable-density interaction. [Internet] [Doctoral dissertation]. University of Illinois – Urbana-Champaign; 2020. [cited 2021 Apr 17].
Available from: http://hdl.handle.net/2142/108502.
Council of Science Editors:
Shields BT. Stationary edge flames in a wedge with hydrodynamic variable-density interaction. [Doctoral Dissertation]. University of Illinois – Urbana-Champaign; 2020. Available from: http://hdl.handle.net/2142/108502
University of New South Wales
2.
Karami, Shahram.
A direct numerical simulation study of a turbulent non-premixed lifted flame.
Degree: Photovoltaics & Renewable Energy Engineering, 2015, University of New South Wales
URL: http://handle.unsw.edu.au/1959.4/54258
;
https://unsworks.unsw.edu.au/fapi/datastream/unsworks:13738/SOURCE02?view=true
► A turbulent lifted slot-jet flame is studied using direct numerical simulation (DNS). A one- step chemistry model is employed with a mixture-fraction dependent activation energy…
(more)
▼ A turbulent lifted slot-jet
flame is studied using direct numerical simulation (DNS). A one- step chemistry model is employed with a mixture-fraction dependent activation energy which can reproduce qualitatively the dependence of laminar burning rate on equivalence ratio that is typical of hydrocarbon fuels.The qualitative structure of the
flame is first examined, confirming some features that have previously been observed in experimental measurements as well as some which have not been previously discussed. Significant differences are observed comparing the present DNS representing a hydrocarbon fuel, and previous DNS representing hydrogen fuel.The statistics of flow and relative
edge-
flame propagation velocity components conditioned on the leading
edge-
flame locations are then examined. The results show that on average, the streamwise
flame propagation and streamwise flow balance, thus demonstrating that
edge-
flame propagation is the basic stabilisation mechanism. Fluctuations of the
edge locations and velocities are, however, significant. It is demonstrated that the edges tend to move in an essentially two-dimensional elliptical pattern (laterally outwards towards the oxidiser, then upstream, then inwards towards the fuel, then downstream again). It is proposed that this is due to the passage of large eddies, as outlined in Su et al. [1]. However, the mechanism is not entirely two-dimensional, and out-of-plane motion is needed to explain how flames escape the high velocity inner region of the jet.Next, the time-averaged structure is examined. The entrainment flow is shown to be diverted around the
flame base causing locally upstream streamwise velocities. A budget of terms in the transport equation for product mass fraction is used to understand the stabilisation from a time-averaged perspective. It is found to be consistent with the instantaneous perspective, featuring a fundamentally two-dimensional structure involving upstream trans- port of products on the lean side balanced by entrainment into richer conditions, while on the rich side, upstream turbulent transport and entrainment from leaner conditions balance the streamwise convection.A complete analysis of the reasons behind the observed trends in the
flame relative propagation velocity has been performed. The mean normalised
edge-
flame speed is less than laminar
flame speed (at around 0.6 of laminar
flame speed) and the
edge-
flame velocity fluctuations are mainly connected with strain rates, scalar dissipation rate, mixture-fraction curvature, product mass fraction curvature and the inner product . These quantities as well as the average normal orientations and nature of the
flame in terms of categorisation of the
edge as premixed or non-premixed go through cyclic fluctuations which appear to be connected with the passage of large eddies and the elliptical pattern of the on-average motion.Overall the results provide strong support for the
edge-
flame theory of
flame stabilisation, but point to significant roles played by large, coherent eddies in…
Advisors/Committee Members: Hawkes, Evatt, Photovoltaics & Renewable Energy Engineering, Faculty of Engineering, UNSW, Talei, Mohsen, Mechanical Engineering, University of Melbourne.
Subjects/Keywords: Edge flame; DNS; Lifted flame; Large eddy structure; Non-premixed flame
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APA (6th Edition):
Karami, S. (2015). A direct numerical simulation study of a turbulent non-premixed lifted flame. (Doctoral Dissertation). University of New South Wales. Retrieved from http://handle.unsw.edu.au/1959.4/54258 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:13738/SOURCE02?view=true
Chicago Manual of Style (16th Edition):
Karami, Shahram. “A direct numerical simulation study of a turbulent non-premixed lifted flame.” 2015. Doctoral Dissertation, University of New South Wales. Accessed April 17, 2021.
http://handle.unsw.edu.au/1959.4/54258 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:13738/SOURCE02?view=true.
MLA Handbook (7th Edition):
Karami, Shahram. “A direct numerical simulation study of a turbulent non-premixed lifted flame.” 2015. Web. 17 Apr 2021.
Vancouver:
Karami S. A direct numerical simulation study of a turbulent non-premixed lifted flame. [Internet] [Doctoral dissertation]. University of New South Wales; 2015. [cited 2021 Apr 17].
Available from: http://handle.unsw.edu.au/1959.4/54258 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:13738/SOURCE02?view=true.
Council of Science Editors:
Karami S. A direct numerical simulation study of a turbulent non-premixed lifted flame. [Doctoral Dissertation]. University of New South Wales; 2015. Available from: http://handle.unsw.edu.au/1959.4/54258 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:13738/SOURCE02?view=true
University of New South Wales
3.
Krisman, Alexander.
Direct numerical simulation of diesel-relevant combustion.
Degree: Mechanical & Manufacturing Engineering, 2016, University of New South Wales
URL: http://handle.unsw.edu.au/1959.4/55498
;
https://unsworks.unsw.edu.au/fapi/datastream/unsworks:37862/SOURCE02?view=true
► Diesel combustion is a major contributor to global energy production. However, despite major improvements to diesel engine design, substantial gaps exist in the fundamental description…
(more)
▼ Diesel combustion is a major contributor to global energy production. However, despite major improvements to diesel engine design, substantial gaps exist in the fundamental description of the in-cylinder combustion process. This impedes the development of simple, predictive models which are necessary for designing improved combustion devices. In particular, only an under-resolved description of ignition and lifted
flame stabilisation exists, due to physical limitations of experimental measurements. Ignition and
flame stabilisation govern the formation of pollutants and combustion efficiency, and so a refined understanding is required. In this thesis, direct numerical simulation (DNS) techniques are applied to idealised configurations that represent facets of diesel combustion. A particular focus is applied to representing the correct thermochemical conditions which result in multi-stage autoignition and a negative temperature coefficient (NTC) regime of ignition delay times. The results were broadly consistent with prior experimental studies, but the well-resolved information also revealed details of several novel combustion features that have not been previously reported. Simulations of lifted laminar flames at NTC conditions with detailed dimethyl ether chemistry observed that
edge flame or hybrid
edge flame/autoignition structures can exist even at diesel-relevant autoignitive conditions, which raises the possibility that
edge flame propagation or a combination of
edge flame propagation and autoignition are responsible for diesel
flame stabilisation. The ignition of a two-dimensional mixing layer at NTC conditions in isotropic turbulence with detailed dimethyl ether chemistry was conducted. A complex ignition process was observed in which two-stage autoignition, cool flames, and hybrid
edge flame/autoignition structures contributed to the overall ignition process. In particular, it was observed that the cool
flame influenced the timing and location of the high temperature ignition. A three-dimensional ignition at NTC conditions with global heptane chemistry was conducted. The results were consistent with the two-dimensional mixing layer results. The results also emphasised the importance of mixing rates in determining the location and timing of high temperature ignition. Overall, this thesis complements prior experimental results, identifies novel combustion features and highlights the substantial modelling challenge presented by diesel combustion.
Advisors/Committee Members: Hawkes, Evatt, Mechanical & Manufacturing Engineering, Faculty of Engineering, UNSW, Kook, Sanghoon, Mechanical & Manufacturing Engineering, Faculty of Engineering, UNSW.
Subjects/Keywords: Negative temperature coefficient; Direct numerical simulation; Diesel-relevant combustion; Triple flame; Two-stage ignition; Polybrachial flame; Tribrachial flame; Ignition; Cool flame; Edge flame
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APA (6th Edition):
Krisman, A. (2016). Direct numerical simulation of diesel-relevant combustion. (Doctoral Dissertation). University of New South Wales. Retrieved from http://handle.unsw.edu.au/1959.4/55498 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:37862/SOURCE02?view=true
Chicago Manual of Style (16th Edition):
Krisman, Alexander. “Direct numerical simulation of diesel-relevant combustion.” 2016. Doctoral Dissertation, University of New South Wales. Accessed April 17, 2021.
http://handle.unsw.edu.au/1959.4/55498 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:37862/SOURCE02?view=true.
MLA Handbook (7th Edition):
Krisman, Alexander. “Direct numerical simulation of diesel-relevant combustion.” 2016. Web. 17 Apr 2021.
Vancouver:
Krisman A. Direct numerical simulation of diesel-relevant combustion. [Internet] [Doctoral dissertation]. University of New South Wales; 2016. [cited 2021 Apr 17].
Available from: http://handle.unsw.edu.au/1959.4/55498 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:37862/SOURCE02?view=true.
Council of Science Editors:
Krisman A. Direct numerical simulation of diesel-relevant combustion. [Doctoral Dissertation]. University of New South Wales; 2016. Available from: http://handle.unsw.edu.au/1959.4/55498 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:37862/SOURCE02?view=true
University of Illinois – Urbana-Champaign
4.
Liao, Kai-Pin.
Solution of strained edge flames by a boundary value method.
Degree: PhD, 0133, 2014, University of Illinois – Urbana-Champaign
URL: http://hdl.handle.net/2142/49763
► Edge flames are fundamental flame structures essential to the description of flame hole dynamics in turbulent combustion and the stabilization of lifted jet flames. In…
(more)
▼ Edge flames are fundamental
flame structures essential to the description of
flame hole dynamics in turbulent combustion and the stabilization of lifted jet flames. In this thesis we concentrate on the role of boundary conditions and how they, in turn, can induce an undesirable streamwise pressure gradient in the trailing diffusion
flame that affects the
edge flame speed. A novel numerical scheme is designed to solve the nonlinear eigenvalue problem based on the variable-density zero Mach number reactive Navier-Stokes equations. It employs a homotopy method to gradually map the solutions from the constant-density
edge flame to the more challenging variable-density
edge flame. The flow and the combustion fields are segregated within an outer Picard iteration embedded in a Newton method, which is solved sequentially using GMRES with proper multigrid preconditioners. This efficient algorithm enables the parametric study of the effects of differential diffusion and strain rate on
edge flame structure and propagation velocity for variable-density flows. Previous studies observe that the ratio of the
edge flame speed to the premixed stoichiometric laminar
flame velocity scales approximately as the square root of the ratio of the cold stream density to the stoichiometric density. In our simulations, where no pressure gradient is present, it is found that the speedup of the normalized
edge flame velocity might be superlinear on the density ratio. This result is new and complements previous results, for different boundary conditions, which suggests that the
edge flame speed is a strong function of the particular hydrodynamic boundary conditions employed in the simulations.
Advisors/Committee Members: Pantano-Rubino, Carlos A. (advisor), Pantano-Rubino, Carlos A. (Committee Chair), Heath, Michael T. (committee member), Hilgenfeldt, Sascha (committee member), Matalon, Moshe (committee member).
Subjects/Keywords: Edge flame; Combustion; Numerical analysis; Boundary value method
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APA (6th Edition):
Liao, K. (2014). Solution of strained edge flames by a boundary value method. (Doctoral Dissertation). University of Illinois – Urbana-Champaign. Retrieved from http://hdl.handle.net/2142/49763
Chicago Manual of Style (16th Edition):
Liao, Kai-Pin. “Solution of strained edge flames by a boundary value method.” 2014. Doctoral Dissertation, University of Illinois – Urbana-Champaign. Accessed April 17, 2021.
http://hdl.handle.net/2142/49763.
MLA Handbook (7th Edition):
Liao, Kai-Pin. “Solution of strained edge flames by a boundary value method.” 2014. Web. 17 Apr 2021.
Vancouver:
Liao K. Solution of strained edge flames by a boundary value method. [Internet] [Doctoral dissertation]. University of Illinois – Urbana-Champaign; 2014. [cited 2021 Apr 17].
Available from: http://hdl.handle.net/2142/49763.
Council of Science Editors:
Liao K. Solution of strained edge flames by a boundary value method. [Doctoral Dissertation]. University of Illinois – Urbana-Champaign; 2014. Available from: http://hdl.handle.net/2142/49763
Louisiana State University
5.
Olatinwo, Mutairu Bolaji.
Use of X-ray K-edge Tomography and Interferometry Imaging Techniques for the Studies of Brominated Flame Retardants.
Degree: PhD, Chemistry, 2016, Louisiana State University
URL: etd-09202016-091910
;
https://digitalcommons.lsu.edu/gradschool_dissertations/4358
► The work presented in this dissertation is based on the studies of flame retardancy performance of various formulations consisting of brominated flame retardants (BFRs: Saytex…
(more)
▼ The work presented in this dissertation is based on the studies of flame retardancy performance of various formulations consisting of brominated flame retardants (BFRs: Saytex 8010 and Green Armor) and their synergist, antimony trioxide (Sb2O3) in high impact polystyrene (HIPS). Chemical flame retardants are incorporated in polymers to improve their flame inhibition for optimal applications in electrical and electronic devices, furniture, printers and more. These flame retardant polymer blends are studied using the Underwriters Laboratory vertical burn test (UL 94) and X-ray imaging techniques such as X-ray K-edge absorption tomography and X-ray grating interferometry.
The UL 94 burn test is initially performed to assess the flammability behavior of flame retardant samples before X-ray imaging methods of burnt and pristine polymer blends. Because the UL 94 test bars are formulated with varying concentrations of a brominated flame retardant (Saytex 8010® or Green Armor®) and a synergist, Sb2O3 into a high impact polystyrene (HIPS), samples pass or fail the UL 94 plastics flammability test based on the burn time and other factors. Then, the X-ray imaging techniques are used to reveal internal features for the flame retardant performance during the burn.
The Underwriters Laboratory 94 test bars are imaged with X-ray K-edge absorption tomography between 12 to 32 keV to assess the bromine and antimony concentration gradient across char layers of partially burnt samples. X-ray grating interferometry on partially burnt samples shows gas bubbles and dark-field scattering ascribed to residual blend inhomogeneity. In addition, X-ray single-shot grating interferometry is used to record X-ray movies of test samples during heating intended to mimic the UL 94 plastics flammability test. Key features such as char layer, gas bubble formation, micro-cracks, and dissolution of the flame retardant in the char layer regions are used in understanding the efficiency of the flame retardant and synergist. The samples that pass the UL 94 test have a thick, highly visible char layer, low bromine and antimony concentration in the char layer as well as an interior rich in gas bubbles. Growth of gas bubbles from flame retardant thermal decomposition is noted in the X-ray phase contrast movies.
Subjects/Keywords: X-ray imaging; K-edge absorption tomography; brominated flame retardants; X-ray grating interferometry
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APA (6th Edition):
Olatinwo, M. B. (2016). Use of X-ray K-edge Tomography and Interferometry Imaging Techniques for the Studies of Brominated Flame Retardants. (Doctoral Dissertation). Louisiana State University. Retrieved from etd-09202016-091910 ; https://digitalcommons.lsu.edu/gradschool_dissertations/4358
Chicago Manual of Style (16th Edition):
Olatinwo, Mutairu Bolaji. “Use of X-ray K-edge Tomography and Interferometry Imaging Techniques for the Studies of Brominated Flame Retardants.” 2016. Doctoral Dissertation, Louisiana State University. Accessed April 17, 2021.
etd-09202016-091910 ; https://digitalcommons.lsu.edu/gradschool_dissertations/4358.
MLA Handbook (7th Edition):
Olatinwo, Mutairu Bolaji. “Use of X-ray K-edge Tomography and Interferometry Imaging Techniques for the Studies of Brominated Flame Retardants.” 2016. Web. 17 Apr 2021.
Vancouver:
Olatinwo MB. Use of X-ray K-edge Tomography and Interferometry Imaging Techniques for the Studies of Brominated Flame Retardants. [Internet] [Doctoral dissertation]. Louisiana State University; 2016. [cited 2021 Apr 17].
Available from: etd-09202016-091910 ; https://digitalcommons.lsu.edu/gradschool_dissertations/4358.
Council of Science Editors:
Olatinwo MB. Use of X-ray K-edge Tomography and Interferometry Imaging Techniques for the Studies of Brominated Flame Retardants. [Doctoral Dissertation]. Louisiana State University; 2016. Available from: etd-09202016-091910 ; https://digitalcommons.lsu.edu/gradschool_dissertations/4358
6.
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
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APA (6th 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 (16th 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 17, 2021.
https://uknowledge.uky.edu/me_etds/117.
MLA Handbook (7th Edition):
Grib, Stephen William. “LAMINAR AND TURBULENT STUDY OF COMBUSTION IN STRATIFIED ENVIRONMENTS USING LASER BASED MEASUREMENTS.” 2018. Web. 17 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 17].
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
University of Southern California
7.
Clayton, David Baldwin.
Experimental investigation of the propagation and extinction
of edge-flames.
Degree: PhD, Mechanical Engineering, 2007, University of Southern California
URL: http://digitallibrary.usc.edu/cdm/compoundobject/collection/p15799coll127/id/527923/rec/2631
► Propagation rates (Uedge) of various hydrocarbon premixed edge-flames are directly measured as a function of global strain rate, mixture strength, and Lewis number (Le). Using…
(more)
▼ Propagation rates (Uedge) of various hydrocarbon
premixed
edge-flames are directly measured as a function of global
strain rate, mixture strength, and Lewis number (Le). Using a
counterflow slot-jet burner with electrical heaters at each end,
both advancing (positive Uedge) and retreating (negative Uedge)
edge-flames can be studied as they propagate across the long
dimension of the burner. Results are presented for twin and single
premixed
edge-flames in terms of the effects of a nondimensional
strain rate and nondimensional heat loss on a scaled propagation
rate. Twin
edge-flames exhibited two extinction limits,
corresponding to a high-strain limit induced by strain and a
low-strain heat loss induced limit. A similar low-strain limit is
identified for single
edge-flames but at high-strain the flames
break apart due to an apparent strain induced instability rather
than extinction. Propagation rates clearly show a strong dependence
on Le and close-up images of the premixed
edge-flames show that
high (low) Le lead to weaker (stronger)
edge-
flame propagation.
Overall, experimental findings agree closely with theoretical
predictions. Additionally, the effects of diffusive-thermal
instability on mixtures with very low Le in the counterflow
strained configuration are examined. Stability maps and propagation
rates for twin premixed, single premixed, and nonpremixed H2-air
flames indicate the importance of heat losses to the burner at low
strain and the dependence of
flame propagation on global strain
rate in relation to the burner configuration. As predicted, low Le
flames in the counterflow configuration form individual and
connected tubes as a means of existing beyond typical extinction
strain rates. The tubes transition into wrinkled flames and then
into planar
flame structures as strain decreases. Propagation rates
for the lean H2 flames generally increase with increasing strain
and are not affected by the instability mode and resulting the
flame shape.
Advisors/Committee Members: Ronney, Paul D. (Committee Chair), Egolfopoulos, Fokion N. (Committee Member), Lee, C. Ted Jr. (Committee Member).
Subjects/Keywords: edge-flame; slot-jet; short-length; hydrocarbon; hydrogen
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APA (6th Edition):
Clayton, D. B. (2007). Experimental investigation of the propagation and extinction
of edge-flames. (Doctoral Dissertation). University of Southern California. Retrieved from http://digitallibrary.usc.edu/cdm/compoundobject/collection/p15799coll127/id/527923/rec/2631
Chicago Manual of Style (16th Edition):
Clayton, David Baldwin. “Experimental investigation of the propagation and extinction
of edge-flames.” 2007. Doctoral Dissertation, University of Southern California. Accessed April 17, 2021.
http://digitallibrary.usc.edu/cdm/compoundobject/collection/p15799coll127/id/527923/rec/2631.
MLA Handbook (7th Edition):
Clayton, David Baldwin. “Experimental investigation of the propagation and extinction
of edge-flames.” 2007. Web. 17 Apr 2021.
Vancouver:
Clayton DB. Experimental investigation of the propagation and extinction
of edge-flames. [Internet] [Doctoral dissertation]. University of Southern California; 2007. [cited 2021 Apr 17].
Available from: http://digitallibrary.usc.edu/cdm/compoundobject/collection/p15799coll127/id/527923/rec/2631.
Council of Science Editors:
Clayton DB. Experimental investigation of the propagation and extinction
of edge-flames. [Doctoral Dissertation]. University of Southern California; 2007. Available from: http://digitallibrary.usc.edu/cdm/compoundobject/collection/p15799coll127/id/527923/rec/2631
8.
Nanduri, Jagannath Ramchandra.
A COMPUTATIONAL STUDY OF THE STRUCTURE, STABILITY, DYNAMICS,
AND RESPONSE OF LOW STRETCH DIFFUSION FLAME.
Degree: PhD, Fluid and Thermal Engineering Science, 2006, Case Western Reserve University School of Graduate Studies
URL: http://rave.ohiolink.edu/etdc/view?acc_num=case1132237973
► Diffusional thermal instabilities occur because of the imbalance between the diffusion of heat and the diffusion of species into the reaction zone. While the phenomenon…
(more)
▼ Diffusional thermal instabilities occur because of the
imbalance between the diffusion of heat and the diffusion of
species into the reaction zone. While the phenomenon of diffusional
thermal instability (DTI) has been recorded in detail in the high
stretch extinction regime of diffusion flames, fundamental
understanding of the DTI near the low stretch radiation induced
extinction regime is lacking. Low stretch flames are relevant to
the fire safety characteristics in many practical engineering
fields. In the current study we investigate the phenomena of DTI
for low stretch diffusion flames with radiative heat loss and map
the one-dimensional and two-dimensional
flame structure, stability
and dynamics. Low stretch nonpremixed combustion including
radiative heat loss is modeled using a planar counterflow
configuration (PCC) and an axisymmetric counterflow configuration
(ACC) to highlight the effects of flow configuration on low stretch
flame instabilities. It is found that the 1D low stretch diffusion
flames in both ACC and PCC systems initially lose their stability
to pulsations which lead to oscillatory extinction for stretch
rates much higher than the 1D steady state extinction limit. The
effects of the Lewis number and reaction rate on this 1D
oscillatory instability is also presented along with a fast Fourier
transform (FFT) analysis to map the frequency and amplitude
characteristics of the oscillatory instability. The stability of
the 2D
flame is mapped using different initial profiles. The 2D
low-stretch diffusion
flame in both ACC and PCC systems was found
to lose its stability to wavy flames very close to the 1D neutral
stability point subsequently leading to steady/unsteady
stationary/traveling cellular flames for PCC system and unsteady
cellular flames for ACC system. These multi-dimensional
flame
phenomena are shown to extend the dynamic extinction limits
predicted by the 1D model. Comparisons between the ACC system and
the PCC system also show the effects of flow configuration on
multi-dimensional
flame phenomenon for low-stretch radiative
diffusion flames. A 2D bifurcation of the
flame solution close to
the 1D low-stretch radiation induced extinction limit is
identified.
Advisors/Committee Members: Sung, Chih-Jen (Advisor).
Subjects/Keywords: Diffusion Flame Stability; Diffusional Thermal Instability; Flame Oscillations; Flame Radiation Interaction; Edge Flames; Cellular Flames
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APA (6th Edition):
Nanduri, J. R. (2006). A COMPUTATIONAL STUDY OF THE STRUCTURE, STABILITY, DYNAMICS,
AND RESPONSE OF LOW STRETCH DIFFUSION FLAME. (Doctoral Dissertation). Case Western Reserve University School of Graduate Studies. Retrieved from http://rave.ohiolink.edu/etdc/view?acc_num=case1132237973
Chicago Manual of Style (16th Edition):
Nanduri, Jagannath Ramchandra. “A COMPUTATIONAL STUDY OF THE STRUCTURE, STABILITY, DYNAMICS,
AND RESPONSE OF LOW STRETCH DIFFUSION FLAME.” 2006. Doctoral Dissertation, Case Western Reserve University School of Graduate Studies. Accessed April 17, 2021.
http://rave.ohiolink.edu/etdc/view?acc_num=case1132237973.
MLA Handbook (7th Edition):
Nanduri, Jagannath Ramchandra. “A COMPUTATIONAL STUDY OF THE STRUCTURE, STABILITY, DYNAMICS,
AND RESPONSE OF LOW STRETCH DIFFUSION FLAME.” 2006. Web. 17 Apr 2021.
Vancouver:
Nanduri JR. A COMPUTATIONAL STUDY OF THE STRUCTURE, STABILITY, DYNAMICS,
AND RESPONSE OF LOW STRETCH DIFFUSION FLAME. [Internet] [Doctoral dissertation]. Case Western Reserve University School of Graduate Studies; 2006. [cited 2021 Apr 17].
Available from: http://rave.ohiolink.edu/etdc/view?acc_num=case1132237973.
Council of Science Editors:
Nanduri JR. A COMPUTATIONAL STUDY OF THE STRUCTURE, STABILITY, DYNAMICS,
AND RESPONSE OF LOW STRETCH DIFFUSION FLAME. [Doctoral Dissertation]. Case Western Reserve University School of Graduate Studies; 2006. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=case1132237973
9.
Mitsingas, Constandino.
Extinction strain rates of n-butanol, 2-butanol and iso-butanol in counterflow non-premixed flamelets.
Degree: MS, 0133, 2012, University of Illinois – Urbana-Champaign
URL: http://hdl.handle.net/2142/30996
► The extinction strain rates of three butanol isomers, (n-butanol, sec-butanol and iso-butanol) were studied experimentally in a counterflow burner, and computationally using a one-dimensional numerical…
(more)
▼ The extinction strain rates of three butanol isomers, (n-butanol, sec-butanol and iso-butanol) were studied experimentally in a counterflow burner, and computationally using a one-dimensional numerical model. The experimental results provided an insight in how the difference between molecular structures affects combustion of the isomers. Molecular branching made the isomers more prone to extinction. They shared a similar maximum temperature, as well as virtually identical high temperature kinetics, which implied that the underlying chemistry that produced difference in extinction strain rates lay, in the low-temperature oxidation steps. A numerical study was employed to calculate the extinction strain rate of n-butanol, and compare it with the experimental results. Good correlation was observed between the simulation and experimental data. During gradual increase of strain that led to extinction in the computations, the maximum temperature as well as the reaction zone thickness decreased. The mole fractions of H and OH radicals decreased, while HCO appeared to remain constant throughout the process. The formation of an annular
edge flame at high strain rates was also observed experimentally for all the isomers. Very rich mixtures (ϕ=4 or higher), produced more resilient
edge flames, than lean (ϕ=0.5 or lower) ones.
Advisors/Committee Members: Kyritsis, Dimitrios C. (advisor).
Subjects/Keywords: butanol isomers; extinction strain rate; annular; edge flame
…that an annular edge flame. Figure
3.4, shows a diffusion flame that has reached a high… …the annular edge
flame [33].
Figure 3.4 Extinction front propagating outwards… …This annular edge flame will sit at a radial position r 0, and have 3 sections as seen in… …reach, and therefore a flat diffusion flame still exists. An edge flame separates the… …diffusion
flame with the extinguished area. The edge flame consists of a premixture of the…
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APA ·
Chicago ·
MLA ·
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CSE |
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APA (6th Edition):
Mitsingas, C. (2012). Extinction strain rates of n-butanol, 2-butanol and iso-butanol in counterflow non-premixed flamelets. (Thesis). University of Illinois – Urbana-Champaign. Retrieved from http://hdl.handle.net/2142/30996
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Mitsingas, Constandino. “Extinction strain rates of n-butanol, 2-butanol and iso-butanol in counterflow non-premixed flamelets.” 2012. Thesis, University of Illinois – Urbana-Champaign. Accessed April 17, 2021.
http://hdl.handle.net/2142/30996.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Mitsingas, Constandino. “Extinction strain rates of n-butanol, 2-butanol and iso-butanol in counterflow non-premixed flamelets.” 2012. Web. 17 Apr 2021.
Vancouver:
Mitsingas C. Extinction strain rates of n-butanol, 2-butanol and iso-butanol in counterflow non-premixed flamelets. [Internet] [Thesis]. University of Illinois – Urbana-Champaign; 2012. [cited 2021 Apr 17].
Available from: http://hdl.handle.net/2142/30996.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Mitsingas C. Extinction strain rates of n-butanol, 2-butanol and iso-butanol in counterflow non-premixed flamelets. [Thesis]. University of Illinois – Urbana-Champaign; 2012. Available from: http://hdl.handle.net/2142/30996
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Saskatchewan
10.
Ezinwa, John Uzodinma.
Modeling full-scale fire test behaviour of polyurethane foams using cone calorimeter data.
Degree: 2009, University of Saskatchewan
URL: http://hdl.handle.net/10388/etd-05302009-093227
► Flexible polyurethane foam (PUF) is a very versatile material ever created. The material is used for various applications and consumer end-use products such as upholstered…
(more)
▼ Flexible polyurethane foam (PUF) is a very versatile material ever created. The material is used for various applications and consumer end-use products such as upholstered furniture and mattresses. The increased use of these polymeric materials causes fire safety concerns. This has led to the development of various regulations and flammability test standards aimed at addressing the hazards associated with polyurethane foam fires. Several fire protection engineering correlations and thermal models have also been developed for the simulation of fire growth behaviour of polyurethane foams. Thus, the overall objective of this research project is to investigate the laboratory test behaviour of this material and then use finer modeling techniques to predict the heat release rate of the specimens, based on information obtained from cone calorimeter tests.
Full-scale fire tests of 10 cm thick polyurethane foams of different sizes were conducted using center and
edge-ignition locations.
Flame spread and heat release rates were compared. For specimens of the same size, center-ignition tests produced
flame areas and peak heat release rates which were respectively 10 and 20% larger compared to
edge-ignition tests. Average
flame spread rates for horizontal and vertical spread were determined, and results showed excellent agreement with literature. Cone calorimeter tests of the specimens were performed using steel
edge frame and open durarock board. Results indicate that different test arrangements and heat sources have significant effects on the fire behaviour of the specimens.
Predictions using the integral convolution model and other fire protection engineering correlations were compared with the full-scale tests results. Results show that the model was more efficient in predicting the heat release rates for
edge-ignition tests than the center-ignition tests. The model also was more successful in predicting the heat release rates during the early part of the growth phase than during the later stages of the fire. The predicted and measured peak heat release rates and total heat release were within 10-15% of one another.
Flame spread and t-squared fire models also gave satisfactory predictions of the full-scale fire behaviour of the specimens.
Advisors/Committee Members: Torvi, David A., Pugsley, Todd, Bugg, James D., Bergstrom, Donald J..
Subjects/Keywords: convolution model; heat release rate prediction; cone calorimeter; flame spread rate; center and edge-ignitions; furniture calorimeter
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APA ·
Chicago ·
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CSE |
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APA (6th Edition):
Ezinwa, J. U. (2009). Modeling full-scale fire test behaviour of polyurethane foams using cone calorimeter data. (Thesis). University of Saskatchewan. Retrieved from http://hdl.handle.net/10388/etd-05302009-093227
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Ezinwa, John Uzodinma. “Modeling full-scale fire test behaviour of polyurethane foams using cone calorimeter data.” 2009. Thesis, University of Saskatchewan. Accessed April 17, 2021.
http://hdl.handle.net/10388/etd-05302009-093227.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Ezinwa, John Uzodinma. “Modeling full-scale fire test behaviour of polyurethane foams using cone calorimeter data.” 2009. Web. 17 Apr 2021.
Vancouver:
Ezinwa JU. Modeling full-scale fire test behaviour of polyurethane foams using cone calorimeter data. [Internet] [Thesis]. University of Saskatchewan; 2009. [cited 2021 Apr 17].
Available from: http://hdl.handle.net/10388/etd-05302009-093227.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Ezinwa JU. Modeling full-scale fire test behaviour of polyurethane foams using cone calorimeter data. [Thesis]. University of Saskatchewan; 2009. Available from: http://hdl.handle.net/10388/etd-05302009-093227
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
11.
Marin Ospina, Yohan Manuel.
Etude de l'influence de la dilution du combustible et de l'oxydant dans le processus de décrochage de flammes-jet non-prémélangées et l'émission de polluants : Study of the influence of air-side and fuel-side dilution on the lifting process of an attached non-premixed jet-flame and on pollutant emissions.
Degree: Docteur es, Physique. Energétique, 2016, Rouen, INSA
URL: http://www.theses.fr/2016ISAM0025
► La compréhension des mécanismes pilotes de la stabilisation des flammes-jet non-prémélangées constitue un point clé dans la caractérisation des modes opératoires des brûleurs industriels fonctionnant…
(more)
▼ La compréhension des mécanismes pilotes de la stabilisation des flammes-jet non-prémélangées constitue un point clé dans la caractérisation des modes opératoires des brûleurs industriels fonctionnant en régime de combustion diluée. Ce travail porte son attention sur l'étude expérimentale de l'influence de la dilution du combustible ou de l'air, sur le processus de décrochage et l'émission des polluants d'une flamme-jet non-prémélangée accrochée au brûleur. L'investigation est menée via un grand nombre d'expériences par combinaison des conditions suivantes : i) dioxyde de carbone (CO2), azote (N2), argon (Ar) et vapeur d'eau (H2Ov), sont utilisés comme diluants ; ii) deux configurations de dilution : dilution de l'air ou dilution du combustible ; iii) un couple de vitesses d'air et de combustible couvrant le domaine d'hystérésis de la flamme dans sa totalité, du régime de jet laminaire à celui de jet turbulent. Ceci permet de discriminer l'influence des effets intrinsèques à la nature du diluant de celle de l'aérodynamique des réactants (combustible et oxydant), dans la stabilité de la flamme accrochée. En particulier, les différences comportementales de la réponse de la flamme à la dilution de l'air ou à celle du combustible, sont analysées. Ces deux configurations de dilution diffèrent par deux effets de mélange, indépendants de la réaction, qui jouent un rôle important dans le cas de la dilution du combustible, mais sont négligeables dans le cas de celle de l'air : i) un effet dû à la modification de la fraction de mélange stœchiométrique. ii) un impact mécanique induit par l'apport de matière (diluants) responsable d'une augmentation de la vitesse des réactants. L'étude se divise en trois principales étapes. D'abord la réponse globale de la flamme à la dilution est étudiée via ses limites de décrochage quantifiées par les fractions molaires critiques des diluants dans l'oxydant ou dans le combustible, mesurées au décrochage. Le nombre de Peclet du combustible, Pef, est identifié comme le nombre adimensionnel qui ordonne ces limites de décrochage de manière homothétique pour tous les diluants. Grâce au comportement homothétique deux coefficients d'affinité, Kd,ox pour le cas de la dilution de l'air et Kd,f pour celle du combustible, sont introduits. Ils sont définis comme le rapport entre la limite de décrochage obtenue avec un diluant et celle obtenue avec le CO2 , à Pef = cste. Ceux-ci permettent l'établissement de deux polynômes génériques décrivant les limites de décrochage pour tous les diluants testés et dans toute la gamme des conditions aérodynamiques étudiées. En effet, Kd,ox et Kd,f englobent l'ensemble des effets physico-chimiques d'un diluant (dilution pure, thermique, propriétés de transport, chimie) et ceux des impacts mécaniques, affectant la stabilité de la flamme. Ils permettent de trouver les lois d'auto-similitude au décrochage pour un diluant chimiquement faible quelconque, à partir des résultats obtenus dans ce travail. Ensuite, une étude locale et détaillée du processus de décrochage induit…
Advisors/Committee Members: Baillot, Françoise (thesis director).
Subjects/Keywords: Flamme-jet non-prémélangée accrochée; Dilution de l'air; Dilution par le CO2,N2, Ar et H2Ov; Bout propagatif de flamme; Rayon d’accrochage; Processus de décrochage; Limite de décrochage; Nombre de Peclet; Vitesse de propagation de flamme laminaire; PIV , LII et chemiluminesence-CH*; Attached non-premixed jet-flame; Fuel dilution; Air dilution; CO2, N2, Ar and H2Ov dilution; Propagation leading-edge; Attachment height; Attachment radius; Lifting process; Lifting limits; Peclet number; Flame propagation velocity
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APA ·
Chicago ·
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CSE |
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APA (6th Edition):
Marin Ospina, Y. M. (2016). Etude de l'influence de la dilution du combustible et de l'oxydant dans le processus de décrochage de flammes-jet non-prémélangées et l'émission de polluants : Study of the influence of air-side and fuel-side dilution on the lifting process of an attached non-premixed jet-flame and on pollutant emissions. (Doctoral Dissertation). Rouen, INSA. Retrieved from http://www.theses.fr/2016ISAM0025
Chicago Manual of Style (16th Edition):
Marin Ospina, Yohan Manuel. “Etude de l'influence de la dilution du combustible et de l'oxydant dans le processus de décrochage de flammes-jet non-prémélangées et l'émission de polluants : Study of the influence of air-side and fuel-side dilution on the lifting process of an attached non-premixed jet-flame and on pollutant emissions.” 2016. Doctoral Dissertation, Rouen, INSA. Accessed April 17, 2021.
http://www.theses.fr/2016ISAM0025.
MLA Handbook (7th Edition):
Marin Ospina, Yohan Manuel. “Etude de l'influence de la dilution du combustible et de l'oxydant dans le processus de décrochage de flammes-jet non-prémélangées et l'émission de polluants : Study of the influence of air-side and fuel-side dilution on the lifting process of an attached non-premixed jet-flame and on pollutant emissions.” 2016. Web. 17 Apr 2021.
Vancouver:
Marin Ospina YM. Etude de l'influence de la dilution du combustible et de l'oxydant dans le processus de décrochage de flammes-jet non-prémélangées et l'émission de polluants : Study of the influence of air-side and fuel-side dilution on the lifting process of an attached non-premixed jet-flame and on pollutant emissions. [Internet] [Doctoral dissertation]. Rouen, INSA; 2016. [cited 2021 Apr 17].
Available from: http://www.theses.fr/2016ISAM0025.
Council of Science Editors:
Marin Ospina YM. Etude de l'influence de la dilution du combustible et de l'oxydant dans le processus de décrochage de flammes-jet non-prémélangées et l'émission de polluants : Study of the influence of air-side and fuel-side dilution on the lifting process of an attached non-premixed jet-flame and on pollutant emissions. [Doctoral Dissertation]. Rouen, INSA; 2016. Available from: http://www.theses.fr/2016ISAM0025
Universidade Estadual de Campinas
12.
Nunes, Claudia Carvalho.
Propriedades estruturais do material vitreo silica-titania produzido pelo metodo do aerosol em chama.
Degree: Faculdade de Engenharia Mecânica; Programa de Pós-Graduação em Engenharia Mecânica, 2008, Universidade Estadual de Campinas
URL: NUNES,
Claudia
Carvalho.
Propriedades
estruturais
do
material
vitreo
silica-titania
produzido
pelo
metodo
do
aerosol
em
chama.
2008.
77f.
Dissertação
(mestrado)
-
Universidade
Estadual
de
Campinas,
Faculdade
de
Engenharia
Mecanica,
Campinas,
SP.
Disponível
em:
<http://www.repositorio.unicamp.br/handle/REPOSIP/264844>.
Acesso
em:
11
ago.
2018.
;
http://repositorio.unicamp.br/jspui/handle/REPOSIP/264844
► Orientador: Carlos Kenichi Suzuki
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
Made available in DSpace on 2018-08-11T16:06:32Z (GMT). No. of bitstreams:…
(more)
▼ Orientador: Carlos Kenichi Suzuki
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
Made available in DSpace on 2018-08-11T16:06:32Z (GMT). No. of bitstreams: 1 Nunes_ClaudiaCarvalho_M.pdf: 7074659 bytes, checksum: 4dec2d1e75a640341af023ba7541f5cb (MD5) Previous issue date: 2008
Resumo: O sistema binário sílica titânia, SiO2-TiO2,apresenta grande interesse tecnológico devido as suas propriedades: ultra-baixo coeficiente de expansão térmico e alto índice de refração. As propriedades são dependentes da quantidade de dopante presente no material. A SiO2-TiO2 é usada na indústria de componentes fotônicos, tais como, lentes, micro-lentes, espelhos e fibras ópticas especiais. Um importante material óptico para litografia no extremo ultravioleta (EUVL) é caracterizado por concentrações próximas a 8 % em peso de TiO2, com estrutura amorfa e transparente num amplo espectro da região UV, visível e IV. A
indústria óptico-eletrônica necessita de fibras ópticas sensoras com alto índice de refração. Este tipo de fibra pode ser obtido através da fabricação de uma fibra de SiO2-TiO2. Amostras com concentrações que variam de 1 a 14 % em peso TiO2 fabricadas pelo método do aerosol em chama foram caracterizadas quanto a suas propriedades estruturais e ópticas. As amostras com concentrações superiores a 7,5 % em peso apresentaram-se translúcidas ou opacas, e com estrutura octaédrica segundo dados de XANES (Absorção de Raios-X próximo à estrutura da borda). A difração de raios-X identificou a fase anatásio da titânia como estrutura octaédrica. Através de tratamentos térmicos a altas temperaturas em chama (> 1500 ºC) obtivemos amostras transparentes no visível, amorfa, contendo 8,2 % em peso. Foi obtido um material com índice de refração de 1,48 para concentração de 10 % em peso de TiO2. Portanto a SiO2-TiO2 é viável para a fabricação de uma fibra com alto índice de refração
The
binary SiO2-TiO2 system presents a great technological importance due to its special properties: ultra low thermal expansion and high refractive index. The properties depend on the amount of dopant present in material. The SiO2-TiO2 is used for the components of photonic industries, such as lenses, mirrors and special fiber optics. As an important optical material for extreme ultraviolet lithography (EUVL), it is characterized by concentrations of ~ 8 wt. % of TiO2, with amorphous structure and transparent for a large UV, visible and IR spectra. The optoelectronic industries needs optical fiber sensor that presents high refractive index. This kind of fiber can be produce by SiO2-TiO2 fiber production. Samples with concentrations varying in the range 1 to 14 wt. % TiO2 made by flame aerosol technique were characterized in terms of structural and optical properties. As-consolidated samples with concentrations up to 7.5 wt. % TiO2 presented itself translucent or opaque with octahedral
structure, according to XANES data (X-ray absorption near-edge structure). The anatase phase of titania was identified by X-ray…
Advisors/Committee Members: UNIVERSIDADE ESTADUAL DE CAMPINAS, Suzuki, Carlos Kenichi, 1945-, Mei, Paulo Roberto, Shinohara, Armando Hideki.
Subjects/Keywords: Materiais nanoestruturados; Vapor - Deposição; Microscopia eletrônica de transmissão; Raios X - Difração; Indice de refração; Absorção de raios X proximo a estrutura da borda; Flame aerosol; Silica-titania; X-Rays diffraction; Transmission electron microscopy; X-ray absorption near-edge strutures; Refractive index
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APA (6th Edition):
Nunes, C. C. (2008). Propriedades estruturais do material vitreo silica-titania produzido pelo metodo do aerosol em chama. (Masters Thesis). Universidade Estadual de Campinas. Retrieved from NUNES, Claudia Carvalho. Propriedades estruturais do material vitreo silica-titania produzido pelo metodo do aerosol em chama. 2008. 77f. Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica, Campinas, SP. Disponível em: <http://www.repositorio.unicamp.br/handle/REPOSIP/264844>. Acesso em: 11 ago. 2018. ; http://repositorio.unicamp.br/jspui/handle/REPOSIP/264844
Chicago Manual of Style (16th Edition):
Nunes, Claudia Carvalho. “Propriedades estruturais do material vitreo silica-titania produzido pelo metodo do aerosol em chama.” 2008. Masters Thesis, Universidade Estadual de Campinas. Accessed April 17, 2021.
NUNES, Claudia Carvalho. Propriedades estruturais do material vitreo silica-titania produzido pelo metodo do aerosol em chama. 2008. 77f. Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica, Campinas, SP. Disponível em: <http://www.repositorio.unicamp.br/handle/REPOSIP/264844>. Acesso em: 11 ago. 2018. ; http://repositorio.unicamp.br/jspui/handle/REPOSIP/264844.
MLA Handbook (7th Edition):
Nunes, Claudia Carvalho. “Propriedades estruturais do material vitreo silica-titania produzido pelo metodo do aerosol em chama.” 2008. Web. 17 Apr 2021.
Vancouver:
Nunes CC. Propriedades estruturais do material vitreo silica-titania produzido pelo metodo do aerosol em chama. [Internet] [Masters thesis]. Universidade Estadual de Campinas; 2008. [cited 2021 Apr 17].
Available from: NUNES, Claudia Carvalho. Propriedades estruturais do material vitreo silica-titania produzido pelo metodo do aerosol em chama. 2008. 77f. Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica, Campinas, SP. Disponível em: <http://www.repositorio.unicamp.br/handle/REPOSIP/264844>. Acesso em: 11 ago. 2018. ; http://repositorio.unicamp.br/jspui/handle/REPOSIP/264844.
Council of Science Editors:
Nunes CC. Propriedades estruturais do material vitreo silica-titania produzido pelo metodo do aerosol em chama. [Masters Thesis]. Universidade Estadual de Campinas; 2008. Available from: NUNES, Claudia Carvalho. Propriedades estruturais do material vitreo silica-titania produzido pelo metodo do aerosol em chama. 2008. 77f. Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica, Campinas, SP. Disponível em: <http://www.repositorio.unicamp.br/handle/REPOSIP/264844>. Acesso em: 11 ago. 2018. ; http://repositorio.unicamp.br/jspui/handle/REPOSIP/264844
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Open Access Theses and Dissertations
