+publisher:"University of Texas – Austin" +contributor:("Ezekoye, Ofodike")

University of Texas – Austin

1. Cabrera, Jan-Michael. Novel suppression methods in fire protection.

Degree: MSin Engineering, Mechanical Engineering, 2013, University of Texas – Austin

► The onset of fire within a compartment can pose a hazard to the occupants and the structure containing the compartment. Fire suppression systems aim to… (more)

▼ The onset of fire within a compartment can pose a hazard to the occupants and the structure containing the compartment. Fire suppression systems aim to either extinguish or suppress an incipient fire before loss of life or damage to the structure can occur. The geometry and use of the compartment as well as the fuel packages within must be taken into account when choosing an appropriate fire suppression system. This thesis explores novel suppression methods inside of compartments. Los Alamos National Laboratories came to the University of Texas Fire Research Group (UTFRG) to characterize and investigate the fire danger inside of nuclear gloveboxes. The first suppression method discussed explores activation tests of a commercial automatic fire suppression system (Fire Foe [superscript TM]) containing heptaflouropropane (FE-36) fire suppressant conducted within a glovebox at the UTFRG's burn structure. Temperature and time to activation data of ten tests at four different fire sizes, three 13 kW, one 20 kW, three 25 kW, and three 50 kW, was taken. Gas temperatures from experiments were compared against NIST's Fire Dynamics Simulator (FDS) gas temperatures with good agreement. The time and spatially averaged net heat flux on a virtual Fire Foe [superscript TM] tube from the FDS simulations were passed to a thermo-physical, semi-empirical, sub-model to predict activation with poor agreement from experimental activation times. A Bayesian parameter inference was later run on the sub-model. While the Bayesian inference approach is able to match sub-model temperatures to experimental temperatures, some non-physical values for heat transfer coefficients and view factors were observed at the lower heat release rate fires. Micro combustion calorimetry (MCC) was used to determine heat of combustion of glovebox glove material and cone calorimetry tests were run to find ignition time versus incident heat flux. Using standard ignition time models, effective model parameters were calibrated. Thermal characterization of the glove material showed that the heat of combustion found from MCC was within the range of heats of combustion for other non-halogenated materials found in the literature. Analysis of the time to ignition tests showed that the glove material should be modeled as thermally thick when one would expect thin behavior. This behavior was attributed to possible heat losses from the back of the glove material. Dry water is expected to have similar suppression characteristics as water mist systems because the dry water particle sizes are on the order of water mist droplet sizes. The major benefit with dry water is the low pressures needed to drive the aerosol. An issue encountered with the dry water was flowing it in the way one would flow normal water. It was found that at low normal and shear stresses, the dry water clathrates would release the water held inside. A possible low shear delivery mechanism was discussed that avoids the ratholing effect. A continuous dry water production system was also designed. Filter loading… Advisors/Committee Members: Ezekoye, Ofodike A. (advisor).

Subjects/Keywords: Fire; Fire suppression; Water mist; Dry water; Glovebox; Gloveboxes; Compartments

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APA (6^th Edition):

Cabrera, J. (2013). Novel suppression methods in fire protection. (Masters Thesis). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/28498

Chicago Manual of Style (16^th Edition):

Cabrera, Jan-Michael. “Novel suppression methods in fire protection.” 2013. Masters Thesis, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/28498.

MLA Handbook (7^th Edition):

Cabrera, Jan-Michael. “Novel suppression methods in fire protection.” 2013. Web. 24 Jan 2021.

Vancouver:

Cabrera J. Novel suppression methods in fire protection. [Internet] [Masters thesis]. University of Texas – Austin; 2013. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/28498.

Council of Science Editors:

Cabrera J. Novel suppression methods in fire protection. [Masters Thesis]. University of Texas – Austin; 2013. Available from: http://hdl.handle.net/2152/28498

University of Texas – Austin

2. Anderson, Austin David. Exploration of statistical approaches to estimating the risks and costs of fire in the United States.

Degree: MSin Engineering, Mechanical Engineering, 2012, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2012-08-6256

► Knowledge of fire risk is crucial for manufacturers and regulators to make correct choices in prescribing fire protection systems, especially flame retardants. Methods of determining… (more)

Subjects/Keywords: NFIRS analysis; Fire statistics; CFAST; Fire risk; Logistic regression; Hypothesis testing; Fire loss estimation

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APA (6^th Edition):

Anderson, A. D. (2012). Exploration of statistical approaches to estimating the risks and costs of fire in the United States. (Masters Thesis). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2012-08-6256

Chicago Manual of Style (16^th Edition):

Anderson, Austin David. “Exploration of statistical approaches to estimating the risks and costs of fire in the United States.” 2012. Masters Thesis, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/ETD-UT-2012-08-6256.

MLA Handbook (7^th Edition):

Anderson, Austin David. “Exploration of statistical approaches to estimating the risks and costs of fire in the United States.” 2012. Web. 24 Jan 2021.

Vancouver:

Anderson AD. Exploration of statistical approaches to estimating the risks and costs of fire in the United States. [Internet] [Masters thesis]. University of Texas – Austin; 2012. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/ETD-UT-2012-08-6256.

Council of Science Editors:

Anderson AD. Exploration of statistical approaches to estimating the risks and costs of fire in the United States. [Masters Thesis]. University of Texas – Austin; 2012. Available from: http://hdl.handle.net/2152/ETD-UT-2012-08-6256

University of Texas – Austin

3. -9605-7743. A study of time-dependent general dynamic equation models for aerosol particle coagulation.

Degree: MSin Engineering, Mechanical Engineering, 2018, University of Texas – Austin

URL: http://hdl.handle.net/2152/72450

► Aerosol dynamics are complex processes that tend to be difficult to model. As a result, various methods have been developed. This makes the selection of… (more)

▼ Aerosol dynamics are complex processes that tend to be difficult to model. As a result, various methods have been developed. This makes the selection of a model an ambiguous process. This study focuses on three models: QMOM, DQMOM, and the constant sectional method. They serve as baseline models for the families of moment and sectional methods. This work aimed to provide some basis from which comparisons could be made among methods. A focus was placed on providing a more thorough comparison among families of solutions rather than simply the runtime and results. To do so, each method was formulated in a manner that would provide comparable run-times and solution accuracies. Coagulation was selected as the phenomenon of interest due to the mathematical difficulties inherent to the process. During the model formulation, assumptions and requirements of each method were identified. A focus was also placed on any algorithms that each method may rely on. Then, the methods were implemented for several benchmark cases. This bottom-up approach allowed for a more involved comparison among the methods. All methods were first optimized for a simple scenario with a known solution. During this process, controllable parameters were varied and resulting impacts on the models were monitored. QMOM proved to be the least sensitive to parameter variation while sectional method performance heavily depended on proper parameter selections. Parameter selections that caused model failure were also identified and were typically able to be attributed to either being a fault in the model or a result of machine arithmetic. Further benchmarking of the optimized models showed DQMOM outperforming QMOM for equivalent quadrature point selections. The sectional method proved capable of providing decent moment values while providing insight as to what the distribution looks like. If such details are desired, then it is the obvious choice. Else, moment methods are preferable when bulk properties suffice. QMOM is good for quick calculations and has a decent application range. DQMOM, however, is the more robust and accurate of the two, with a vastly larger application range. Its main downside is more user intuition being required for proper implementation. Advisors/Committee Members: Ezekoye, Ofodike A. (advisor).

Subjects/Keywords: Aerosol dynamics; General Dynamic Equation; Aerosol particle coagulation; QMOM; DQMOM; Constant sectional method

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APA (6^th Edition):

-9605-7743. (2018). A study of time-dependent general dynamic equation models for aerosol particle coagulation. (Masters Thesis). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/72450

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Chicago Manual of Style (16^th Edition):

-9605-7743. “A study of time-dependent general dynamic equation models for aerosol particle coagulation.” 2018. Masters Thesis, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/72450.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

MLA Handbook (7^th Edition):

-9605-7743. “A study of time-dependent general dynamic equation models for aerosol particle coagulation.” 2018. Web. 24 Jan 2021.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Vancouver:

-9605-7743. A study of time-dependent general dynamic equation models for aerosol particle coagulation. [Internet] [Masters thesis]. University of Texas – Austin; 2018. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/72450.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Council of Science Editors:

-9605-7743. A study of time-dependent general dynamic equation models for aerosol particle coagulation. [Masters Thesis]. University of Texas – Austin; 2018. Available from: http://hdl.handle.net/2152/72450

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

University of Texas – Austin

4. Hron, Joel Maurice. The importance of sediment roughness on the reflection coefficient for normal incidence reflections.

Degree: MSin Engineering, Mechanical Engineering, 2011, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2011-05-2911

► This research experimentally shows the effect of sediment roughness characteristics on the acoustic reflection coefficient. This information is useful when trying to classify various types… (more)

Subjects/Keywords: Acoustics; Sediment characterization; Sediment roughness; Reflection coefficient; Single beam echo-sounder; Signal processing

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APA (6^th Edition):

Hron, J. M. (2011). The importance of sediment roughness on the reflection coefficient for normal incidence reflections. (Masters Thesis). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2011-05-2911

Chicago Manual of Style (16^th Edition):

Hron, Joel Maurice. “The importance of sediment roughness on the reflection coefficient for normal incidence reflections.” 2011. Masters Thesis, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/ETD-UT-2011-05-2911.

MLA Handbook (7^th Edition):

Hron, Joel Maurice. “The importance of sediment roughness on the reflection coefficient for normal incidence reflections.” 2011. Web. 24 Jan 2021.

Vancouver:

Hron JM. The importance of sediment roughness on the reflection coefficient for normal incidence reflections. [Internet] [Masters thesis]. University of Texas – Austin; 2011. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/ETD-UT-2011-05-2911.

Council of Science Editors:

Hron JM. The importance of sediment roughness on the reflection coefficient for normal incidence reflections. [Masters Thesis]. University of Texas – Austin; 2011. Available from: http://hdl.handle.net/2152/ETD-UT-2011-05-2911

University of Texas – Austin

5. Chang, Michael Kazuto. Development of a testing protocol for insulation ignition by wildland fire embers.

Degree: MSin Engineering, Mechanical Engineering, 2017, University of Texas – Austin

URL: http://hdl.handle.net/2152/64118

► Wildfire embers, also known as firebrands, are one of the dominant fire spread elements in wildfire growth. These embers are associated with the ignition of… (more)

▼ Wildfire embers, also known as firebrands, are one of the dominant fire spread elements in wildfire growth. These embers are associated with the ignition of structures at the wildland-urban interface (WUI) and there is effort to understand the mechanisms by which they ignite homes. One of the vulnerable areas of homes at the WUI is the attic space. The ignition of attic materials by embers is not a well characterized problem, and so an effort was made to better understand the parameters critical to this issue. This thesis details the assessment of the ignition processes for embers attacking attic materials. An experimental procedure was developed to create consistent embers of specific sizes with well characterized thermal properties. These embers were transferred to various fuel beds, where air flow conditions were adjusted to determine which conditions would cause the fuel bed to ignite, extinguish, or smolder. The materials tested were extruded polystyrene (XPS), expanded polystyrene (EPS), polyurethane (PUR), flame retarded/non-flame retarded denim, and flame retarded/non-flame retarded cellulose, which are all typical insulation materials found in the attic. The differences between flame retarded and non-flame retarded materials were highlighted through these material comparisons. Two configurations of embers, a single large ember vs. an equivalent mass pile of fragmented embers, were tested. Thermocouples and IR camera recordings were used to monitor fuel bed and ember temperatures, in order to investigate the signatures of ignition Once the critical ignition parameter space was defined, a better understanding of the material properties was required to discern what material features were responsible for the ember flammability observations. In order to accomplish this, simple methodologies for measuring thermal conductivity, specific heat, and density were created. The oxygen consumption (cone) calorimeter was used to determine flammability characteristics of the materials, such as heat release rates and ignition times, while thermogravimetric analysis was used to define the material degradation behavior. Finally, X-ray diffraction was explored in order to find the presence of flame retardants in the various materials. Advisors/Committee Members: Ezekoye, Ofodike A. (advisor), Marr, Kevin C (committee member).

Subjects/Keywords: Firebrands; Ignition; Embers; Insulation ignition

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APA (6^th Edition):

Chang, M. K. (2017). Development of a testing protocol for insulation ignition by wildland fire embers. (Masters Thesis). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/64118

Chicago Manual of Style (16^th Edition):

Chang, Michael Kazuto. “Development of a testing protocol for insulation ignition by wildland fire embers.” 2017. Masters Thesis, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/64118.

MLA Handbook (7^th Edition):

Chang, Michael Kazuto. “Development of a testing protocol for insulation ignition by wildland fire embers.” 2017. Web. 24 Jan 2021.

Vancouver:

Chang MK. Development of a testing protocol for insulation ignition by wildland fire embers. [Internet] [Masters thesis]. University of Texas – Austin; 2017. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/64118.

Council of Science Editors:

Chang MK. Development of a testing protocol for insulation ignition by wildland fire embers. [Masters Thesis]. University of Texas – Austin; 2017. Available from: http://hdl.handle.net/2152/64118

University of Texas – Austin

6. Singh, Ravi Ishwar. Direct numerical simulation and reaction path analysis of titania formation in flame synthesis.

Degree: MSin Engineering, Mechanical Engineering, 2012, University of Texas – Austin

URL: http://hdl.handle.net/2152/23016

► Flame-based synthesis is an attractive industrial process for the large scale generation of nanoparticles. In this aerosol process, a gasifi ed precursor is injected into… (more)

▼ Flame-based synthesis is an attractive industrial process for the large scale generation of nanoparticles. In this aerosol process, a gasifi ed precursor is injected into a high-temperature turbulent flame, where oxidation followed by particle nucleation and other solid phase dynamics create nanoparticles. Precursor oxidation, which ultimately leads to nucleation, is strongly influenced by the turbulent flame dynamics. Here, direct numerical simulation (DNS) of a canonical homogeneous flow is used to understand the interaction between a methane/air flame and titanium tetrachloride oxidation to titania. Detailed chemical kinetics is used to describe the combustion and precursor oxidation processes. Results show that the initial precursor decomposition is heavily influenced by the gas phase temperature field. However, temperature insensitivity of subsequent reactions in the precursor oxidation pathway slow down conversion to the titania. Consequently, titania formation occurs at much longer time scales compared to that of hydrocarbon oxidation. Further, only a fraction of the precursor is converted to titania, and a signi cant amount of partially-oxidized precursor species are formed. Introducing the precursor in the oxidizer stream as opposed to the fuel stream has only a minimal impact on the oxidation dynamics. In order to understand modeling issues, the DNS results are compared with the laminar flamelet model. It is shown that the flamelet assumption qualitatively reproduces the oxidation structure. Further, reduced oxygen concentration in the near-flame location critically a ffects titania formation. The DNS results also show that titania forms on the lean and rich sides of the flame. A reaction path analysis (RPA) is conducted. The results illustrate the di ffering reaction pathways of the detailed chemical mechanism depending on the composition of the mixture. The RPA results corroborate with the DNS results that titania formation is maximized at two mixture fraction values, one on the lean side of the flame, and one on the rich side. Advisors/Committee Members: Ezekoye, Ofodike A. (advisor), Raman, Venkat (advisor).

Subjects/Keywords: Direct numerical simulation (DNS); Combustion; Turbulence; Titania; Nanoparticles; Detailed chemical kinetics

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APA (6^th Edition):

Singh, R. I. (2012). Direct numerical simulation and reaction path analysis of titania formation in flame synthesis. (Masters Thesis). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/23016

Chicago Manual of Style (16^th Edition):

Singh, Ravi Ishwar. “Direct numerical simulation and reaction path analysis of titania formation in flame synthesis.” 2012. Masters Thesis, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/23016.

MLA Handbook (7^th Edition):

Singh, Ravi Ishwar. “Direct numerical simulation and reaction path analysis of titania formation in flame synthesis.” 2012. Web. 24 Jan 2021.

Vancouver:

Singh RI. Direct numerical simulation and reaction path analysis of titania formation in flame synthesis. [Internet] [Masters thesis]. University of Texas – Austin; 2012. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/23016.

Council of Science Editors:

Singh RI. Direct numerical simulation and reaction path analysis of titania formation in flame synthesis. [Masters Thesis]. University of Texas – Austin; 2012. Available from: http://hdl.handle.net/2152/23016

University of Texas – Austin

7. -9627-1539. Using contoured endwalls to achieve proper scaling for a gas turbine vane model using a low speed testing facility.

Degree: MSin Engineering, Mechanical Engineering, 2015, University of Texas – Austin

URL: http://hdl.handle.net/2152/31987

► The testing of gas turbine vane and blade models is often performed in low speed, large scale infinite cascade facilities to allow for more precise… (more)

▼ The testing of gas turbine vane and blade models is often performed in low speed, large scale infinite cascade facilities to allow for more precise machining of parts and more accurately measured data. However, flow in engine scale turbines reaches well into the compressible gas range while low speed facilities run in the incompressible fluid range, and engines have three dimensional flow effects due to having contoured endwall while traditional cascade testing has not accounted for three dimensional effects. This means that matching pressure distributions cannot be achieved between engine scale and experimental scale through simple geometric scaling of the model. In the past, these differences in pressure distributions were often overcome by changing the geometry of the test model. An alternate to this is to use contoured enwalls inside the test facility to allow the decreased area to correct for the differences in pressure distributions. In this work, the concept of using contoured endwalls in the test facility to achieve a matching pressure distribution on a vane was tested. Three dimensional computation fluid dynamics (CFD) simulations were used to find the correct geometry for the contoured endwalls. The proposed endwalls and vanes were then built and tested in a low speed simulated infinite cascade testing facility. The pressure distribution was measured at low turbulence levels and Re = 1.1×10⁶. It was shown that the pressure distribution in the test model with contoured endwalls did match within uncertainty the pressure distribution predicted for the engine scale using CFD. Thus, contoured endwalls can be said to be a viable option to force the matching of pressure distribution of a model test vane to that of engine conditions. Additionally, a vane model with a constant heat flux surface was tested at the same conditions, and the heat transfer coefficient distribution for the vane was determined. It was shown that the endwalls had minimal effects on the spanwise uniformity of the heat transfer coefficient distribution. Advisors/Committee Members: Bogard, David G. (advisor), Ezekoye, Ofodike (committee member).

Subjects/Keywords: Endwall; Heat transfer; Coefficient; Vane; Low speed facility; Simulated infinite cascade; Pressure distribution; Turbine cooling

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APA (6^th Edition):

-9627-1539. (2015). Using contoured endwalls to achieve proper scaling for a gas turbine vane model using a low speed testing facility. (Masters Thesis). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/31987

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Chicago Manual of Style (16^th Edition):

-9627-1539. “Using contoured endwalls to achieve proper scaling for a gas turbine vane model using a low speed testing facility.” 2015. Masters Thesis, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/31987.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

MLA Handbook (7^th Edition):

-9627-1539. “Using contoured endwalls to achieve proper scaling for a gas turbine vane model using a low speed testing facility.” 2015. Web. 24 Jan 2021.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Vancouver:

-9627-1539. Using contoured endwalls to achieve proper scaling for a gas turbine vane model using a low speed testing facility. [Internet] [Masters thesis]. University of Texas – Austin; 2015. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/31987.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Council of Science Editors:

-9627-1539. Using contoured endwalls to achieve proper scaling for a gas turbine vane model using a low speed testing facility. [Masters Thesis]. University of Texas – Austin; 2015. Available from: http://hdl.handle.net/2152/31987

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

University of Texas – Austin

8. Abbasi, Mustafa Zafar. Development of a sonar system to assist firefighter navigation in low-visibility high temperature environments.

Degree: MSin Engineering, Mechanical Engineering, 2013, University of Texas – Austin

URL: http://hdl.handle.net/2152/28675

► Firefighters routinely have to go through buildings with reduced visibility due to smoke. Moving through even the simplest apartment building can become a perilous task… (more)

Subjects/Keywords: Firefighting; Sonar; High temperature

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APA (6^th Edition):

Abbasi, M. Z. (2013). Development of a sonar system to assist firefighter navigation in low-visibility high temperature environments. (Masters Thesis). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/28675

Chicago Manual of Style (16^th Edition):

Abbasi, Mustafa Zafar. “Development of a sonar system to assist firefighter navigation in low-visibility high temperature environments.” 2013. Masters Thesis, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/28675.

MLA Handbook (7^th Edition):

Abbasi, Mustafa Zafar. “Development of a sonar system to assist firefighter navigation in low-visibility high temperature environments.” 2013. Web. 24 Jan 2021.

Vancouver:

Abbasi MZ. Development of a sonar system to assist firefighter navigation in low-visibility high temperature environments. [Internet] [Masters thesis]. University of Texas – Austin; 2013. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/28675.

Council of Science Editors:

Abbasi MZ. Development of a sonar system to assist firefighter navigation in low-visibility high temperature environments. [Masters Thesis]. University of Texas – Austin; 2013. Available from: http://hdl.handle.net/2152/28675

9. Martin, Karl Matthew. Acoustic modification of sooting combustion.

Degree: PhD, Mechanical Engineering., 2002, University of Texas – Austin

URL: http://hdl.handle.net/2152/1654

Subjects/Keywords: Combustion engineering; Soot – Environmental aspects; Sound

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APA (6^th Edition):

Martin, K. M. (2002). Acoustic modification of sooting combustion. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/1654

Chicago Manual of Style (16^th Edition):

Martin, Karl Matthew. “Acoustic modification of sooting combustion.” 2002. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/1654.

MLA Handbook (7^th Edition):

Martin, Karl Matthew. “Acoustic modification of sooting combustion.” 2002. Web. 24 Jan 2021.

Vancouver:

Martin KM. Acoustic modification of sooting combustion. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2002. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/1654.

Council of Science Editors:

Martin KM. Acoustic modification of sooting combustion. [Doctoral Dissertation]. University of Texas – Austin; 2002. Available from: http://hdl.handle.net/2152/1654

10. Overholt, Kristopher James. Forward and inverse modeling of fire physics towards fire scene reconstructions.

Degree: PhD, Civil Engineering, 2013, University of Texas – Austin

URL: http://hdl.handle.net/2152/21971

► Fire models are routinely used to evaluate life safety aspects of building design projects and are being used more often in fire and arson investigations… (more)

▼ Fire models are routinely used to evaluate life safety aspects of building design projects and are being used more often in fire and arson investigations as well as reconstructions of firefighter line-of-duty deaths and injuries. A fire within a compartment effectively leaves behind a record of fire activity and history (i.e., fire signatures). Fire and arson investigators can utilize these fire signatures in the determination of cause and origin during fire reconstruction exercises. Researchers conducting fire experiments can utilize this record of fire activity to better understand the underlying physics. In all of these applications, the fire heat release rate (HRR), location of a fire, and smoke production are important parameters that govern the evolution of thermal conditions within a fire compartment. These input parameters can be a large source of uncertainty in fire models, especially in scenarios in which experimental data or detailed information on fire behavior are not available. To better understand fire behavior indicators related to soot, the deposition of soot onto surfaces was considered. Improvements to a soot deposition submodel were implemented in a computational fluid dynamics (CFD) fire model. To better understand fire behavior indicators related to fire size, an inverse HRR methodology was developed that calculates a transient HRR in a compartment based on measured temperatures resulting from a fire source. To address issues related to the uncertainty of input parameters, an inversion framework was developed that has applications towards fire scene reconstructions. Rather than using point estimates of input parameters, a statistical inversion framework based on the Bayesian inference approach was used to determine probability distributions of input parameters. These probability distributions contain uncertainty information about the input parameters and can be propagated through fire models to obtain uncertainty information about predicted quantities of interest. The Bayesian inference approach was applied to various fire problems and coupled with zone and CFD fire models to extend the physical capability and accuracy of the inversion framework. Example applications include the estimation of both steady-state and transient fire sizes in a compartment, material properties related to pyrolysis, and the location of a fire in a compartment. Advisors/Committee Members: Ezekoye, Ofodike A. (advisor).

Subjects/Keywords: Fire modeling; Inverse modeling; Arson investigation; Soot deposition; Bayesian inference

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APA (6^th Edition):

Overholt, K. J. (2013). Forward and inverse modeling of fire physics towards fire scene reconstructions. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/21971

Chicago Manual of Style (16^th Edition):

Overholt, Kristopher James. “Forward and inverse modeling of fire physics towards fire scene reconstructions.” 2013. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/21971.

MLA Handbook (7^th Edition):

Overholt, Kristopher James. “Forward and inverse modeling of fire physics towards fire scene reconstructions.” 2013. Web. 24 Jan 2021.

Vancouver:

Overholt KJ. Forward and inverse modeling of fire physics towards fire scene reconstructions. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2013. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/21971.

Council of Science Editors:

Overholt KJ. Forward and inverse modeling of fire physics towards fire scene reconstructions. [Doctoral Dissertation]. University of Texas – Austin; 2013. Available from: http://hdl.handle.net/2152/21971

11. Kurzawski, Andrew Joseph. Ablation and ignition by impinging jet flows.

Degree: MSin Engineering, Mechanical Engineering, 2013, University of Texas – Austin

URL: http://hdl.handle.net/2152/23684

► Two separate heat transfer problems that involve jet flows impinging on a reacting target are studied through modeling and experimentation. The first system is an… (more)

Subjects/Keywords: Heat transfer; Ablation; Jet flow; Mechanical engineering; Fire research; Fire protection

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APA (6^th Edition):

Kurzawski, A. J. (2013). Ablation and ignition by impinging jet flows. (Masters Thesis). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/23684

Chicago Manual of Style (16^th Edition):

Kurzawski, Andrew Joseph. “Ablation and ignition by impinging jet flows.” 2013. Masters Thesis, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/23684.

MLA Handbook (7^th Edition):

Kurzawski, Andrew Joseph. “Ablation and ignition by impinging jet flows.” 2013. Web. 24 Jan 2021.

Vancouver:

Kurzawski AJ. Ablation and ignition by impinging jet flows. [Internet] [Masters thesis]. University of Texas – Austin; 2013. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/23684.

Council of Science Editors:

Kurzawski AJ. Ablation and ignition by impinging jet flows. [Masters Thesis]. University of Texas – Austin; 2013. Available from: http://hdl.handle.net/2152/23684

University of Texas – Austin

12. -6737-7043. Temperature fluctuation analysis for GRACE twin satellites.

Degree: MSin Engineering, Mechanical engineering, 2016, University of Texas – Austin

URL: http://hdl.handle.net/2152/41966

► The overall objective of this research project is to find patterns and give a rudimentary explanation of these patterns in how heat flows through and… (more)

Subjects/Keywords: Heat transfer; GRACE twin satellites; Temperature frequency; Beta prime angle; Radiation; Conduction; Umbra; Penumbra; Gravity field; Solar flux; Earth infrared; Albedo

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APA (6^th Edition):

-6737-7043. (2016). Temperature fluctuation analysis for GRACE twin satellites. (Masters Thesis). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/41966

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Chicago Manual of Style (16^th Edition):

-6737-7043. “Temperature fluctuation analysis for GRACE twin satellites.” 2016. Masters Thesis, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/41966.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

MLA Handbook (7^th Edition):

-6737-7043. “Temperature fluctuation analysis for GRACE twin satellites.” 2016. Web. 24 Jan 2021.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Vancouver:

-6737-7043. Temperature fluctuation analysis for GRACE twin satellites. [Internet] [Masters thesis]. University of Texas – Austin; 2016. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/41966.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Council of Science Editors:

-6737-7043. Temperature fluctuation analysis for GRACE twin satellites. [Masters Thesis]. University of Texas – Austin; 2016. Available from: http://hdl.handle.net/2152/41966

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

University of Texas – Austin

13. Sadeghi Neshat, Sajjad. Compositional three-phase relative permeability and capillary pressure models using Gibbs free energy.

Degree: MSin Engineering, Mechanical engineering, 2016, University of Texas – Austin

URL: http://hdl.handle.net/2152/41767

► Both relative permeability and capillary pressure depend on composition as well as saturation, but classical models neglect this dependence. The objective of this research was… (more)

▼ Both relative permeability and capillary pressure depend on composition as well as saturation, but classical models neglect this dependence. The objective of this research was to develop coupled three-phase relative permeability and capillary pressure models for implementation in a four-phase flow compositional equation-of-state simulator. The models applied to several complex but practical reservoir simulation problems. Models independent of phase label have many advantages in terms of both numerical stability and physical consistency. Identification of hydrocarbon and aqueous phases based on their molar Gibbs Free Energy (GFE) is a key feature of the new model. Instead of using labels (gas/oil/2nd liquid/aqueous) to define permeability parameters such as end points, residual saturation and exponents, the parameters are continuously interpolated between reference values using the Gibbs free energy of each phase at each time step. Consequently, the formulation used to implement other relevant physical parameters must be consistent with the new approach. A comprehensive but simple vii algorithm was developed for this purpose. The algorithm allows for very general threephase hysteresis in both relative permeability and capillary pressure. An important part of this thesis is analyzing the results of a recent series of experiments on the effect composition on relative permeability. These new data were used to calibrate the new GFE relative permeability model and apply it in a compositional reservoir simulator. The robustness of the new GFE model was shown through complex simulations such as solvent flooding, miscible/immiscible WAG processes, well stimulation processes using solvents to remove condensate and/or water blocks in both conventional and unconventional formations and other challenging applications involving both mass transfer between phases and phase changes. The interpolation of relative permeability parameters based on GFE instead of phase labels completely solves the discontinuity problem caused by phase flipping or misidentification. Therefore, simulations run significantly faster and are physically correct. The novelty of this research is in integrating and unifying relevant physical parameters including trapping number, hysteresis and capillary pressure into one rigorous algorithm with compositional consistency and in the development and application of a practical procedure for numerical compositional reservoir simulations. Advisors/Committee Members: Pope, G. A. (advisor), Ezekoye, Ofodike E. (advisor), Lake, Larry (committee member).

Subjects/Keywords: Three-phase; Relative permeability; Capillary pressure; Gibbs free energy; Compositional simulation; Phase identification

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APA (6^th Edition):

Sadeghi Neshat, S. (2016). Compositional three-phase relative permeability and capillary pressure models using Gibbs free energy. (Masters Thesis). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/41767

Chicago Manual of Style (16^th Edition):

Sadeghi Neshat, Sajjad. “Compositional three-phase relative permeability and capillary pressure models using Gibbs free energy.” 2016. Masters Thesis, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/41767.

MLA Handbook (7^th Edition):

Sadeghi Neshat, Sajjad. “Compositional three-phase relative permeability and capillary pressure models using Gibbs free energy.” 2016. Web. 24 Jan 2021.

Vancouver:

Sadeghi Neshat S. Compositional three-phase relative permeability and capillary pressure models using Gibbs free energy. [Internet] [Masters thesis]. University of Texas – Austin; 2016. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/41767.

Council of Science Editors:

Sadeghi Neshat S. Compositional three-phase relative permeability and capillary pressure models using Gibbs free energy. [Masters Thesis]. University of Texas – Austin; 2016. Available from: http://hdl.handle.net/2152/41767

University of Texas – Austin

14. Ebi, Dominik Fabian. Boundary layer flashback of swirl flames.

Degree: PhD, Aerospace Engineering, 2016, University of Texas – Austin

URL: http://hdl.handle.net/2152/38721

► Flame flashback in the boundary layer of swirling flows is investigated experimentally in a model swirl combustor. The model combustor features a mixing tube with… (more)

▼ Flame flashback in the boundary layer of swirling flows is investigated experimentally in a model swirl combustor. The model combustor features a mixing tube with an axial swirler and an attached center body. The findings provide novel insight into the mechanism facilitating boundary layer flashback of swirl flames. Turbulent, lean-premixed flames of methane and hydrogen are studied at atmospheric pressure and bulk flow velocities up to 5 m/s. Hydrogen contents range from 0% to 95% and equivalence ratios range from 0.4 to 1. The focus in the present work is on the upstream flame propagation inside the mixing tube. Stereoscopic particle image velocimetry (PIV) is applied at kilohertz-rate to provide the time-resolved, three-component velocity field. The flame front is detected simultaneously based on the acquired Mie scattering images. Simultaneous high-speed chemiluminescence imaging provides the overall flame shape and global propagation direction. In addition to the planar measurements, a technique capable of detecting the instantaneous, time-resolved, 3D flame front topography is developed and applied successfully. Oil droplets, which vaporize in the preheat zone of the flame, serve as the marker for the flame front. The droplets are illuminated with a laser and imaged from four different views followed by a tomographic reconstruction to obtain the volumetric particle field. The velocity field in the unburnt gas is measured using tomographic PIV. The resulting data include the simultaneous 3D flame front and volumetric velocity field at 5 kHz. Flashback is found to occur in the form of large-scale, convex-shaped flame tongues, which swirl in the bulk flow direction as they propagate in the negative axial direction along the center body wall. Gas dilatation associated with the heat release imposes a blockage effect on the approach flow, which causes a 3D deflection of streamlines. As a result, a region of negative axial velocity forms along the leading side of the flame tongues, which facilitates flashback. These regions of negative axial velocity, already observed in previous studies, are shown to be the result of a predominantly swirling fluid motion as opposed to boundary layer separation or flow recirculation. The effect of hydrogen addition on flashback is investigated. Flashback occurs at significantly leaner conditions for hydrogen-rich flames, but the mechanism driving flashback is found to be independent of the hydrogen content for the conditions investigated in the present work. Quantitative differences in the flame-flow interaction between methane and hydrogen-rich flashbacks are discussed in detail. Advisors/Committee Members: Clemens, Noel T. (advisor), Ezekoye, Ofodike A (committee member), Raja, Laxminarayan (committee member), Raman, Venkat (committee member), Varghese, Philip L (committee member).

Subjects/Keywords: Turbulent flames; Flashback; High-speed PIV; Tomographic PIV

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APA (6^th Edition):

Ebi, D. F. (2016). Boundary layer flashback of swirl flames. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/38721

Chicago Manual of Style (16^th Edition):

Ebi, Dominik Fabian. “Boundary layer flashback of swirl flames.” 2016. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/38721.

MLA Handbook (7^th Edition):

Ebi, Dominik Fabian. “Boundary layer flashback of swirl flames.” 2016. Web. 24 Jan 2021.

Vancouver:

Ebi DF. Boundary layer flashback of swirl flames. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2016. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/38721.

Council of Science Editors:

Ebi DF. Boundary layer flashback of swirl flames. [Doctoral Dissertation]. University of Texas – Austin; 2016. Available from: http://hdl.handle.net/2152/38721

University of Texas – Austin

15. Ganesh, Hari Sai. Modeling, control, and optimization of an industrial austenitization furnace.

Degree: PhD, Chemical Engineering, 2019, University of Texas – Austin

URL: http://dx.doi.org/10.26153/tsw/1047

► Steel production and processing is both energy-intensive (2% of overall energy consumption) and one of the biggest contributors to CO₂ emissions. Its use is projected… (more)

▼ Steel production and processing is both energy-intensive (2% of overall energy consumption) and one of the biggest contributors to CO₂ emissions. Its use is projected to increase by 1.5 times that of present levels (around 1.6 billion metric tonnes per year) by 2050 to meet the needs of a growing population. The main goal of this research is to minimize the energy consumption of a steel quench hardening (or heat treating) process, currently in operation at an industrial partner, by mathematical modeling, optimization, advanced control, and heat integration. The quench hardening processes consists of heating pre-finished metal parts to a certain temperature in a continuously operating furnace (austenitization), followed by rapid cooling (quenching) in water, brine or oil to induce desired metallurgical properties like hardness, toughness, shear strength, tensile strength, etc. The novelty of this work lies in the two scale modeling approach considered to solve the furnace energy consumption minimization problem. We improve a previously developed two-dimensional (2D) physicsbased model of the heat treating furnace that computes the energy usage of the furnace and the part temperature distribution as a function of time and position within the furnace under temperature feedback control. We predict the effect of process variables on microstructural evolution of the parts using an empirical relation reported in the literature and their consequent effects on the metallurgical properties of the quenched product. The physics-based model combined with the empirical model is used to simulate the furnace operation for a batch of parts processed sequentially under heuristic temperature set points with a simple linear control strategy suggested by the operators of the plant. We then minimize the energy consumption of the furnace without compromising the product quality by real-time optimization (RTO), model predictive control (MPC), and heat integration using radiant recuperators. Energy savings of 3.7%, 15.93%, and 20.88% were obtained under model predictive control, heat integration, and optimized set points respectively compared to reference heuristic operation case without heat integration and MPC. Advisors/Committee Members: Baldea, Michael (advisor), Edgar, Thomas F. (advisor), Ezekoye, Ofodike A. (committee member), Rochelle, Gary T. (committee member).

Subjects/Keywords: Austenitization; Furnace; Modeling; Optimization; Control

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APA (6^th Edition):

Ganesh, H. S. (2019). Modeling, control, and optimization of an industrial austenitization furnace. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://dx.doi.org/10.26153/tsw/1047

Chicago Manual of Style (16^th Edition):

Ganesh, Hari Sai. “Modeling, control, and optimization of an industrial austenitization furnace.” 2019. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://dx.doi.org/10.26153/tsw/1047.

MLA Handbook (7^th Edition):

Ganesh, Hari Sai. “Modeling, control, and optimization of an industrial austenitization furnace.” 2019. Web. 24 Jan 2021.

Vancouver:

Ganesh HS. Modeling, control, and optimization of an industrial austenitization furnace. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2019. [cited 2021 Jan 24]. Available from: http://dx.doi.org/10.26153/tsw/1047.

Council of Science Editors:

Ganesh HS. Modeling, control, and optimization of an industrial austenitization furnace. [Doctoral Dissertation]. University of Texas – Austin; 2019. Available from: http://dx.doi.org/10.26153/tsw/1047

University of Texas – Austin

16. Strand, James Stephen. Statistical methods for the analysis of DSMC simulations of hypersonic shocks.

Degree: PhD, Aerospace Engineering, 2012, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2012-05-5384

► In this work, statistical techniques were employed to study the modeling of a hypersonic shock with the Direct Simulation Monte Carlo (DSMC) method, and to… (more)

▼ In this work, statistical techniques were employed to study the modeling of a hypersonic shock with the Direct Simulation Monte Carlo (DSMC) method, and to gain insight into how the model interacts with a set of physical parameters. Direct Simulation Monte Carlo (DSMC) is a particle based method which is useful for simulating gas dynamics in rarefied and/or highly non-equilibrium flowfields. A DSMC code was written and optimized for use in this research. The code was developed with shock tube simulations in mind, and it includes a number of improvements which allow for the efficient simulation of 1D, hypersonic shocks. Most importantly, a moving sampling region is used to obtain an accurate steady shock profile from an unsteady, moving shock wave. The code is MPI parallel and an adaptive load balancing scheme ensures that the workload is distributed properly between processors over the course of a simulation. Global, Monte Carlo based sensitivity analyses were performed in order to determine which of the parameters examined in this work most strongly affect the simulation results for two scenarios: a 0D relaxation from an initial high temperature state and a hypersonic shock. The 0D relaxation scenario was included in order to examine whether, with appropriate initial conditions, it can be viewed in some regards as a substitute for the 1D shock in a statistical sensitivity analysis. In both analyses sensitivities were calculated based on both the square of the Pearson correlation coefficient and the mutual information. The quantity of interest (QoI) chosen for these analyses was the NO density profile. This vector QoI was broken into a set of scalar QoIs, each representing the density of NO at a specific point in time (for the relaxation) or a specific streamwise location (for the shock), and sensitivities were calculated for each scalar QoI based on both measures of sensitivity. The sensitivities were then integrated over the set of scalar QoIs to determine an overall sensitivity for each parameter. A weighting function was used in the integration in order to emphasize sensitivities in the region of greatest thermal and chemical non-equilibrium. The six parameters which most strongly affect the NO density profile were found to be the same for both scenarios, which provides justification for the claim that a 0D relaxation can in some situations be used as a substitute model for a hypersonic shock. These six parameters are the pre-exponential constants in the Arrhenius rate equations for the N2 dissociation reaction N2 + N ⇄ 3N, the O2 dissociation reaction O2 + O ⇄ 3O, the NO dissociation reactions NO + N ⇄ 2N + O and NO + O ⇄ N + 2O, and the exchange reactions N2 + O ⇄ NO + N and NO + O ⇄ O2 + N. After identification of the most sensitive parameters, a synthetic data calibration was performed to demonstrate that the statistical inverse problem could be solved for the 0D relaxation scenario. The calibration was performed using the QUESO code, developed at the PECOS center at UT… Advisors/Committee Members: Goldstein, David Benjamin, doctor of aeronautics (advisor), Moser, Robert (committee member), Varghese, Philip (committee member), Ezekoye, Ofodike (committee member), Prudencio, Ernesto (committee member).

Subjects/Keywords: DSMC; MCMC; Sensitivity analysis

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

APA (6^th Edition):

Strand, J. S. (2012). Statistical methods for the analysis of DSMC simulations of hypersonic shocks. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2012-05-5384

Chicago Manual of Style (16^th Edition):

Strand, James Stephen. “Statistical methods for the analysis of DSMC simulations of hypersonic shocks.” 2012. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/ETD-UT-2012-05-5384.

MLA Handbook (7^th Edition):

Strand, James Stephen. “Statistical methods for the analysis of DSMC simulations of hypersonic shocks.” 2012. Web. 24 Jan 2021.

Vancouver:

Strand JS. Statistical methods for the analysis of DSMC simulations of hypersonic shocks. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2012. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/ETD-UT-2012-05-5384.

Council of Science Editors:

Strand JS. Statistical methods for the analysis of DSMC simulations of hypersonic shocks. [Doctoral Dissertation]. University of Texas – Austin; 2012. Available from: http://hdl.handle.net/2152/ETD-UT-2012-05-5384

University of Texas – Austin

17. Kumar, Ankur, Ph. D. Model based operation of industrial steam methane reformers using large scale sensor data.

Degree: PhD, Chemical engineering, 2016, University of Texas – Austin

URL: http://hdl.handle.net/2152/46443

► Large quantities of hydrogen are consumed in refineries and for production of important chemicals such as ammonia and methanol. Declining crude-oil quality and increased fertilizer… (more)

▼ Large quantities of hydrogen are consumed in refineries and for production of important chemicals such as ammonia and methanol. Declining crude-oil quality and increased fertilizer demands, among others, have led to further increase in hydrogen demand. A significant portion (~80%) of industrial hydrogen consumption is met via natural-gas steam methane reforming. This process takes place in a large scale, high-temperature, and highly energy-intensive unit called a steam methane reformer (SMR), where endothermic reforming reactions are carried out in hundreds of catalyst-filled tubes placed in a gas-fired furnace. A typical modern hydrogen production plant consumes a substantial amount (~10⁵ GJ) of natural gas per day. The overall productivity (energy consumed per unit H2 produced) of the plant is strongly dependent on how efficiently the SMR is operated, which further depends on the spatial temperature distribution inside the furnace, where a more uniform distribution paves the way for reduced plant-wide energy use. Controlling the temperature distribution is, however, a challenging task due to the distributed nature of the system and the difficulty of obtaining distributed temperature measurements (the latter associated with the extreme operating conditions and the complex geometry of the furnace). In this thesis, results concerning the monitoring of temperature distribution in an industrial SMR furnace using a large array of infrared camera sensors, which produce a significant stream of data regarding the furnace temperature distribution, are presented. Specifically, strategies for homogenization of reformer tube-wall temperature distribution, also called furnace balancing, using reduced-order and physics-based models are developed. First, for a proof-of-concept study, a computational fluid dynamics (CFD) model of a small scale SMR system is developed as a substitute for a real plant. A proper orthogonal decomposition-based reduced-order linear model is used to modulate the fuel distribution among the burners. It is shown that a reduced-order empirical model with much lower computational requirements, when trained with sufficiently rich data, can be a viable substitute to the detailed modeling of the complex thermal and flow interactions in the furnace. Next, the data-driven modeling approach is extended to a real full-scale industrial SMR furnace. Shortcomings in popular empirical modeling approaches such as partial least squares (PLS) and ordinary least squares (OLS) are highlighted and a novel egg-crate SMR (EC-SMR) model is proposed. The model is calibrated using temperature measurements from the infrared cameras. Experimental results confirm that the proposed framework has excellent performance providing a 44% improvement in temperature distribution non-uniformity. While computationally intensive CFD models are not suitable for use in furnace efficiency optimization calculations, empirical models (data-driven reduced-order models) have limited accuracy when wide changes in operating conditions are… Advisors/Committee Members: Edgar, Thomas F. (advisor), Baldea, Michael (advisor), Bonnecaze, Roger T (committee member), Ezekoye, Ofodike A (committee member), Beaman, Joseph J (committee member).

Subjects/Keywords: Steam methane reformer; Distributed parameter control; Plantwide optimization; Hydrogen plant optimization; Smart manufacturing

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APA (6^th Edition):

Kumar, Ankur, P. D. (2016). Model based operation of industrial steam methane reformers using large scale sensor data. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/46443

Chicago Manual of Style (16^th Edition):

Kumar, Ankur, Ph D. “Model based operation of industrial steam methane reformers using large scale sensor data.” 2016. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/46443.

MLA Handbook (7^th Edition):

Kumar, Ankur, Ph D. “Model based operation of industrial steam methane reformers using large scale sensor data.” 2016. Web. 24 Jan 2021.

Vancouver:

Kumar, Ankur PD. Model based operation of industrial steam methane reformers using large scale sensor data. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2016. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/46443.

Council of Science Editors:

Kumar, Ankur PD. Model based operation of industrial steam methane reformers using large scale sensor data. [Doctoral Dissertation]. University of Texas – Austin; 2016. Available from: http://hdl.handle.net/2152/46443

University of Texas – Austin

18. Avendaño Valderrama, Alejandro Raul. Pretensioned box beams : prestress transfer and shear behavior.

Degree: PhD, Civil Engineering, 2011, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2011-12-4530

► Pretensioned concrete box beams have been used in highway bridges for more than half a century. Due to their geometry, they have often been used… (more)

▼ Pretensioned concrete box beams have been used in highway bridges for more than half a century. Due to their geometry, they have often been used as a viable alternative to the classic I-shaped girders. Box beams are highly effective in cases where speed of construction is a priority. However, the detailing and design of box beams are more complicated than that of I-shaped girders. The flow of forces at the beam’s end blocks must be understood in order to detail reinforcement adequately. The following were the objectives of this research study: (i) quantify the demands placed on box beam end blocks upon prestress transfer, (ii) characterize the demands placed on box beam end blocks upon the application of superimposed loads, (iii) evaluate the effects of alternative void geometries at skewed ends of box beams on curing temperatures, (iv) based on the knowledge gained in (i), (ii) and (iii), improve the box beam end blocks, (v) test the improved end block under worst case scenario demands at prestress transfer and under extreme loading conditions, and (vi) validate currently used shear strength design methodologies in their application to pretensioned box beams. In order to achieve these objectives, an experimental program was conducted. The experimental program included the load testing of ten 4B28 and five 5B40 box beams, for a total of twenty nine load tests. The influence of several factors that distinguish box beam behavior from the better-understood I-shaped girder behavior was studied. Additionally, the experimental program included the fabrication, instrumentation and early-age behavior study of five 5B40 box beams. The first three beams were used to vii assess the behavior of box beams fabricated with the current TxDOT standard details (from December 2006). The fourth beam incorporated modifications to the standard reinforcement details based on the observations made through the study of the first three 5B40 box beams. The last specimen corresponded to a new box beam cross section (5XB40) optimized to be used in a spread-box beams configuration. Advisors/Committee Members: Bayrak, Oguzhan, 1969- (advisor), Jirsa, James O. (committee member), Wood, Sharon L. (committee member), Breen, John E. (committee member), Ezekoye, Ofodike (committee member).

Subjects/Keywords: Box beams; Pretensioned; Shear

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APA (6^th Edition):

Avendaño Valderrama, A. R. (2011). Pretensioned box beams : prestress transfer and shear behavior. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2011-12-4530

Chicago Manual of Style (16^th Edition):

Avendaño Valderrama, Alejandro Raul. “Pretensioned box beams : prestress transfer and shear behavior.” 2011. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/ETD-UT-2011-12-4530.

MLA Handbook (7^th Edition):

Avendaño Valderrama, Alejandro Raul. “Pretensioned box beams : prestress transfer and shear behavior.” 2011. Web. 24 Jan 2021.

Vancouver:

Avendaño Valderrama AR. Pretensioned box beams : prestress transfer and shear behavior. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2011. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/ETD-UT-2011-12-4530.

Council of Science Editors:

Avendaño Valderrama AR. Pretensioned box beams : prestress transfer and shear behavior. [Doctoral Dissertation]. University of Texas – Austin; 2011. Available from: http://hdl.handle.net/2152/ETD-UT-2011-12-4530

University of Texas – Austin

19. -9386-4956. Analytical solutions of pressure-production tests with permanent multisensors in oil gas and water zones.

Degree: PhD, Petroleum Engineering, 2019, University of Texas – Austin

URL: http://dx.doi.org/10.26153/tsw/3102

► The petroleum industry has invested millions of dollars in developing technologies for improving the monitoring methods for wells. These wells may have up to eight… (more)

Subjects/Keywords: Well-test; Partial penetrate well; Multiphase; Moving boundary

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APA (6^th Edition):

-9386-4956. (2019). Analytical solutions of pressure-production tests with permanent multisensors in oil gas and water zones. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://dx.doi.org/10.26153/tsw/3102

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Chicago Manual of Style (16^th Edition):

-9386-4956. “Analytical solutions of pressure-production tests with permanent multisensors in oil gas and water zones.” 2019. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://dx.doi.org/10.26153/tsw/3102.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

MLA Handbook (7^th Edition):

-9386-4956. “Analytical solutions of pressure-production tests with permanent multisensors in oil gas and water zones.” 2019. Web. 24 Jan 2021.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Vancouver:

-9386-4956. Analytical solutions of pressure-production tests with permanent multisensors in oil gas and water zones. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2019. [cited 2021 Jan 24]. Available from: http://dx.doi.org/10.26153/tsw/3102.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Council of Science Editors:

-9386-4956. Analytical solutions of pressure-production tests with permanent multisensors in oil gas and water zones. [Doctoral Dissertation]. University of Texas – Austin; 2019. Available from: http://dx.doi.org/10.26153/tsw/3102

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

University of Texas – Austin

20. Koo, Heeseok. Large-eddy simulations of scramjet engines.

Degree: PhD, Aerospace Engineering, 2011, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2011-05-3203

► The main objective of this dissertation is to develop large-eddy simulation (LES) based computational tools for supersonic inlet and combustor design. In the recent past,… (more)

▼ The main objective of this dissertation is to develop large-eddy simulation (LES) based computational tools for supersonic inlet and combustor design. In the recent past, LES methodology has emerged as a viable tool for modeling turbulent combustion. LES computes the large scale mixing process accurately, thereby providing a better starting point for small-scale models that describe the combustion process. In fact, combustion models developed in the context of Reynolds-averaged Navier Stokes (RANS) equations exhibit better predictive capability when used in the LES framework. The development of a predictive computational tool based on LES will provide a significant boost to the design of scramjet engines. Although LES has been used widely in the simulation of subsonic turbulent flows, its application to high-speed flows has been hampered by a variety of modeling and numerical issues. In this work, we develop a comprehensive LES methodology for supersonic flows, focusing on the simulation of scramjet engine components. This work is divided into three sections. First, a robust compressible flow solver for a generalized high-speed flow configuration is developed. By using carefully designed numerical schemes, dissipative errors associated with discretization methods for high-speed flows are minimized. Multiblock and immersed boundary method are used to handle scramjet-specific geometries. Second, a new combustion model for compressible reactive flows is developed. Subsonic combustion models are not directly applicable in high-speed flows due to the coupling between the energy and velocity fields. Here, a probability density function (PDF) approach is developed for high-speed combustion. This method requires solution to a high dimensional PDF transport equation, which is achieved through a novel direct quadrature method of moments (DQMOM). The combustion model is validated using experiments on supersonic reacting flows. Finally, the LES methodology is used to study the inlet-isolator component of a dual-mode scramjet. The isolator is a critical component that maintains the compression shock structures required for stable combustor operation in ramjet mode. We simulate unsteady dynamics inside an experimental isolator, including the propagation of an unstart event that leads to loss of compression. Using a suite of simulations, the sensitivity of the results to LES models and numerical implementation is studied. Advisors/Committee Members: Raman, Venkat (advisor), Varghese, Philip L. (committee member), Clemens, Noel T. (committee member), Moser, Robert D. (committee member), Ezekoye, Ofodike A. (committee member).

Subjects/Keywords: Large-eddy simulations; Combustion model; DQMOM; Direct quadrature method of moments; Compressible flow; Shock capturing method; Hyperviscosity; Scramjet; Inlet-isolator; Unstart

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APA (6^th Edition):

Koo, H. (2011). Large-eddy simulations of scramjet engines. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2011-05-3203

Chicago Manual of Style (16^th Edition):

Koo, Heeseok. “Large-eddy simulations of scramjet engines.” 2011. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/ETD-UT-2011-05-3203.

MLA Handbook (7^th Edition):

Koo, Heeseok. “Large-eddy simulations of scramjet engines.” 2011. Web. 24 Jan 2021.

Vancouver:

Koo H. Large-eddy simulations of scramjet engines. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2011. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/ETD-UT-2011-05-3203.

Council of Science Editors:

Koo H. Large-eddy simulations of scramjet engines. [Doctoral Dissertation]. University of Texas – Austin; 2011. Available from: http://hdl.handle.net/2152/ETD-UT-2011-05-3203

University of Texas – Austin

21. Marr, Kevin Chek-Shing. Investigation of acoustically forced non-premixed jet flames in crossflow.

Degree: PhD, Aerospace Engineering, 2011, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2011-05-3133

► The work presented here discusses the effects of strong acoustic forcing on jet flames in crossflow (JFICF) and the physical mechanisms behind theses effects. For… (more)

▼ The work presented here discusses the effects of strong acoustic forcing on jet flames in crossflow (JFICF) and the physical mechanisms behind theses effects. For forced non-premixed JFICF, the jet fuel flow is modulated using an acoustic speaker system, which results in a drastic decrease in flame length and soot luminosity. Forced JFICF are characterized by periodic ejections of high-momentum, deeply penetrating vortical structures, which draws air into the jet nozzle and enhances mixing in the nearfield region of the jet. Mixture fraction images of the non-reacting forced jet in crossflow are obtained from acetone planar laser-induced fluorescence and show that the ejected jet fluid is effectively partially premixed. Flame luminosity images and exhaust gas measurements show that forced non-premixed JFICF exhibit similar characteristics to unforced partially-premixed JFICF. Both strong forcing and air dilution result in net reductions in NOx, but increases in CO and unburned hydrocarbons. NOx scaling analysis is presented for both forced non-premixed and unforced partially-premixed flames. Using flame volume arguments, EINOx scales with amplitude ratio for forced non- premixed flames, but does not scale with air dilution for unforced partially-premixed flames. The difference in scaling behavior is attributed to differences in flame structure. The effect of forcing on the flowfield dynamics of non-premixed JFICF is investigated using high-speed stereoscopic particle image velocimetry and luminosity imaging. The frequency spectra of the windward and lee-side flame base motions obtained from luminosity movies of the forced JFICF show a peak at the forcing frequency in the lee-side spectrum, but not on the windward-side spectrum. The lee-side flame base responds to the forcing frequency because the lee-side flame base stabilizes closer to the jet exit. The windward-side flame base does not respond to the forcing frequency because the integrated effect of the incident crossflow and vortical ejections leads to extinction of the flame base. From the PIV measurements, flowfield statistics are conditioned at the flame base. The local gas velocity at the flame base did not collapse for forced and unforced JFICF and was found to exceed 3SL. The flame propagation velocity was determined from the motion of the flame base, which is inferred from regions of evaporated seed particles in the time-resolved PIV images. The flame propagation velocity collapses for forced and unforced JFICF, which implies that the flame base is an edge flame; however, the most probable propagation velocity, approximately 2-3SL, is larger than propagation velocity predicted by edge flame theories. A possible explanation is that the flame propagation is enhanced by turbulent intensities and flame curvature. Advisors/Committee Members: Clemens, Noel T. (advisor), Ezekoye, Ofodike A. (advisor), Hall, Matthew J. (committee member), Raman, Venkat (committee member), Varghese, Philip L. (committee member).

Subjects/Keywords: Pulsed combustion; Acoustics; Jet flames; Emissions; Flame stability

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APA (6^th Edition):

Marr, K. C. (2011). Investigation of acoustically forced non-premixed jet flames in crossflow. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2011-05-3133

Chicago Manual of Style (16^th Edition):

Marr, Kevin Chek-Shing. “Investigation of acoustically forced non-premixed jet flames in crossflow.” 2011. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/ETD-UT-2011-05-3133.

MLA Handbook (7^th Edition):

Marr, Kevin Chek-Shing. “Investigation of acoustically forced non-premixed jet flames in crossflow.” 2011. Web. 24 Jan 2021.

Vancouver:

Marr KC. Investigation of acoustically forced non-premixed jet flames in crossflow. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2011. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/ETD-UT-2011-05-3133.

Council of Science Editors:

Marr KC. Investigation of acoustically forced non-premixed jet flames in crossflow. [Doctoral Dissertation]. University of Texas – Austin; 2011. Available from: http://hdl.handle.net/2152/ETD-UT-2011-05-3133

University of Texas – Austin

22. -3840-5313. The RailPAc arc.

Degree: PhD, Aerospace Engineering, 2018, University of Texas – Austin

URL: http://hdl.handle.net/2152/68944

► This dissertation will detail work examining the plasma arc of the RailPAc magnetohydrodynamic flow actuator. Initial studies of the RailPAc arc have shown that the… (more)

▼ This dissertation will detail work examining the plasma arc of the RailPAc magnetohydrodynamic flow actuator. Initial studies of the RailPAc arc have shown that the arc formation and propagation processes are highly stochastic and in many cases unpredictable. This insight motivated most of the work in this dissertation to better understand the nature of arc propagation, towards the design of a predictable and well behaved high intensity gliding arc. The work consists of several experiment based studies examining the RailPAc plasma arc, focusing on electrical characterization, spectroscopic temperature analysis, narrow-band-imaging species evolution within the arc, and the effects of electrode surface oxidation states on the propagation of the arc. Additional experimental studies examined the effects of external magnetic fields and rod configurations, the effect of the wall near the electrodes, as well as long term damage on copper and elkonite electrodes. Computational studies examined phenomena which were difficult or not possible to characterize experimentally. This includes mechanisms of wall stabilization, root mobility over oxidized surfaces, and simulations of the arc column in two and three dimensions to examine coupling of the arc to surrounding gas. The key contributions of this work can be split into two parts, both of which have experimental and computational components. The first is the characterization of the RailPAc arc dynamics (electrically, chemically, and physically) and its coupling to the surrounding flow. This is examined experimentally with spectroscopy, high-speed narrow-band imaging, and electrical measurements, as well as computationally with commercial arc modeling software solving fluid flow coupled to Maxwell’s equations in potential form. The second is the examination of the RailPAc arc root interaction with the electrode surface, particularly the anode root which has seen very little examination compared to the cathode in previous research efforts directed at high intensity gliding arcs. Both of these are combined in a computational effort to model the RailPAc arc column in two and three dimensions. Advisors/Committee Members: Raja, Laxminarayan L. (advisor), Sirohi, Jayant (advisor), Goldstein, David (committee member), Varghese, Philip (committee member), Ezekoye, Ofodike (committee member).

Subjects/Keywords: Thermal plasma; Gliding arc; High intensity arc; Flow control; Aerospace; Oxidation; Plasma flow actuation

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APA (6^th Edition):

-3840-5313. (2018). The RailPAc arc. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/68944

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Chicago Manual of Style (16^th Edition):

-3840-5313. “The RailPAc arc.” 2018. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/68944.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

MLA Handbook (7^th Edition):

-3840-5313. “The RailPAc arc.” 2018. Web. 24 Jan 2021.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Vancouver:

-3840-5313. The RailPAc arc. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2018. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/68944.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Council of Science Editors:

-3840-5313. The RailPAc arc. [Doctoral Dissertation]. University of Texas – Austin; 2018. Available from: http://hdl.handle.net/2152/68944

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

University of Texas – Austin

23. -2456-1577. Anisotropic hybrid turbulence modeling with specific application to the simulation of pulse-actuated dynamic stall control.

Degree: PhD, Mechanical engineering, 2015, University of Texas – Austin

URL: http://hdl.handle.net/2152/33393

► Experimental studies have shown pulse actuated dynamic stall control may provide a simple means to significantly increase the performance of lifting surfaces and expand their… (more)

Subjects/Keywords: Turbulence; RANS; LES; Hybrid; V2f; Simulation; Anisotropic; Inhomogeneous; Resolution; SGS; Structure-function; Stall control

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APA (6^th Edition):

-2456-1577. (2015). Anisotropic hybrid turbulence modeling with specific application to the simulation of pulse-actuated dynamic stall control. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/33393

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Author name may be incomplete

Chicago Manual of Style (16^th Edition):

-2456-1577. “Anisotropic hybrid turbulence modeling with specific application to the simulation of pulse-actuated dynamic stall control.” 2015. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/33393.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

MLA Handbook (7^th Edition):

-2456-1577. “Anisotropic hybrid turbulence modeling with specific application to the simulation of pulse-actuated dynamic stall control.” 2015. Web. 24 Jan 2021.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Vancouver:

-2456-1577. Anisotropic hybrid turbulence modeling with specific application to the simulation of pulse-actuated dynamic stall control. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2015. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/33393.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Council of Science Editors:

-2456-1577. Anisotropic hybrid turbulence modeling with specific application to the simulation of pulse-actuated dynamic stall control. [Doctoral Dissertation]. University of Texas – Austin; 2015. Available from: http://hdl.handle.net/2152/33393

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Author name may be incomplete

University of Texas – Austin

24. Lietz, Christopher Fernandez. Large-Eddy simulation of gas turbine combustors using Flamelet Manifold methods.

Degree: PhD, Aerospace engineering, 2015, University of Texas – Austin

URL: http://hdl.handle.net/2152/32911

► The main objective of this work was to develop a large-eddy simulation (LES) based computational tool for application to both premixed and non- premixed combustion… (more)

▼ The main objective of this work was to develop a large-eddy simulation (LES) based computational tool for application to both premixed and non- premixed combustion of low-Mach number flows in gas turbines. In the recent past, LES methodology has emerged as a viable tool for modeling turbulent combustion. LES is particularly well-suited for the compu- tation of large scale mixing, which provides a firm starting point for the small scale models which describe the reaction processes. Even models developed in the context of Reynolds averaged Navier-Stokes (RANS) exhibit superior results in the LES framework. Although LES is a widespread topic of research, in industrial applications it is often seen as a less attractive option than RANS, which is computationally inexpensive and often returns sufficiently accurate results. However, there are many commonly encountered problems for which RANS is unsuitable. This work is geared towards such instances, with a solver developed for use in unsteady reacting flows on unstructured grids. The work is divided into two sections. First, a robust CFD solver for a generalized incompressible, reacting flow configuration is developed. The computational algorithm, which com- bines elements of the low-Mach number approximation and pressure projection methods with other techniques, is described. Coupled to the flow solver is a combustion model based on the flamelet progress variable approach (FPVA), adapted to current applications. Modifications which promote stability and accuracy in the context of unstructured meshes are also implemented. Second, the LES methodology is used to study three specific problems. The first is a channel geometry with a lean premixed hydrogen mixture, in which the unsteady flashback phenomenon is induced. DNS run in tandem is used for establishing the validity of the LES. The second problem is a swirling gas turbine combustor, which extends the channel flashback study to a more practical application with stratified premixed methane and hydrogen/methane mixtures. Experimental results are used for comparison. Finally, the third problem tests the solver’s abilities further, using a more complex fuel JP-8, Lagrangian fuel droplets, and a complicated geometry. In this last configu- ration, experimental results validate early simulations while later simulations examine the physics of reacting sprays under high centripetal loading. Advisors/Committee Members: Clemens, Noel T. (advisor), Raman, Venkat (advisor), Ezekoye, Ofodike A (committee member), Goldstein, David B (committee member), Varghese, Philip L (committee member).

Subjects/Keywords: Computational fluid dynamics (CFD); Large-Eddy simulation (LES); Combustion; Flamelet progress variable approach (FPVA)

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

APA (6^th Edition):

Lietz, C. F. (2015). Large-Eddy simulation of gas turbine combustors using Flamelet Manifold methods. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/32911

Chicago Manual of Style (16^th Edition):

Lietz, Christopher Fernandez. “Large-Eddy simulation of gas turbine combustors using Flamelet Manifold methods.” 2015. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/32911.

MLA Handbook (7^th Edition):

Lietz, Christopher Fernandez. “Large-Eddy simulation of gas turbine combustors using Flamelet Manifold methods.” 2015. Web. 24 Jan 2021.

Vancouver:

Lietz CF. Large-Eddy simulation of gas turbine combustors using Flamelet Manifold methods. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2015. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/32911.

Council of Science Editors:

Lietz CF. Large-Eddy simulation of gas turbine combustors using Flamelet Manifold methods. [Doctoral Dissertation]. University of Texas – Austin; 2015. Available from: http://hdl.handle.net/2152/32911

University of Texas – Austin

25. -3704-0597. Quantitative measurements of ablation-products transport in supersonic turbulent flows using planar laser-induced fluorescence.

Degree: PhD, Aerospace engineering, 2015, University of Texas – Austin

URL: http://hdl.handle.net/2152/31340

► A recently-developed experimental technique based on the sublimation of naphthalene, which enables imaging of the dispersion of a passive scalar using planar laser-induced fluorescence (PLIF),… (more)

▼ A recently-developed experimental technique based on the sublimation of naphthalene, which enables imaging of the dispersion of a passive scalar using planar laser-induced fluorescence (PLIF), is applied to a Mach 5 turbulent boundary layer and a NASA Orion capsule flowfield. To enable the quantification of naphthalene PLIF images, quantitative fluorescence and quenching measurements were made in a temperature- and pressure-regulated test cell. The test cell measurements were of the naphthalene fluorescence lifetime and integrated fluorescence signal over the temperature range of 100 K to 525 K and pressure range of 1 kPa to 40 kPa in air. These data enabled the calculation of naphthalene fluorescence yield and absorption cross section over the range of temperatures and pressures tested, which were then fit to simple functional forms for use in the calibration of the PLIF images. Quantitative naphthalene PLIF images in the Mach 5 boundary layer revealed large-scale naphthalene vapor structures that were regularly ejected out to wall distances of approximately y/δ = 0.6 for a field of view that spanned 3δ to 5δ downstream of the trailing edge of the naphthalene insert. The magnitude of the calculated naphthalene mole fraction in these structures at y/δ = 0.2 ranged from approximately 1-6% of the saturation mole fraction at the wind tunnel recovery temperature and static pressure. An uncertainty analysis showed that the uncertainty in the inferred naphthalene mole fraction measurements was ± 20%. Mean mole fraction profiles collected at different streamwise locations were normalized by the mole fraction measured at the wall and a characteristic height of the scalar boundary layer, causing the profiles to collapse into one “universal” mole fraction profile. Two-dimensional fields of naphthalene mole fraction were also obtained simultaneously with velocity by using particle image velocimetry (PIV) and PLIF. The images show large-scale naphthalene vapor structures that coincide with regions of relatively low streamwise velocity. The covariance of naphthalene mole fraction with velocity indicates that an ejection mechanism is transporting low-momentum, high-scalar-concentration fluid away from the wall, resulting in the protrusions of naphthalene vapor evident in the instantaneous PLIF images. Lastly, naphthalene PLIF was used to visualize the dispersion of gas-phase ablation products on a scaled Orion capsule model at four different angles of attack at Mach 5. High concentrations of scalar were imaged in the capsule recirculation region. Additionally, intermittent turbulent structures were visualized on the heat shield surface, particularly for the 12° and 52° AoA cases. Advisors/Committee Members: Clemens, Noel T. (advisor), Danehy, Paul M (committee member), Ezekoye, Ofodike A (committee member), Raja, Laxminarayan (committee member), Varghese, Philip L (committee member).

Subjects/Keywords: PLIF; PIV; Scalar transport; Supersonic flows; Ablation; Reentry; Orion capsule; Turbulence; Naphthalene; Fluorescence; Laser diagnostics

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APA (6^th Edition):

-3704-0597. (2015). Quantitative measurements of ablation-products transport in supersonic turbulent flows using planar laser-induced fluorescence. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/31340

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Author name may be incomplete

Chicago Manual of Style (16^th Edition):

-3704-0597. “Quantitative measurements of ablation-products transport in supersonic turbulent flows using planar laser-induced fluorescence.” 2015. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/31340.

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Author name may be incomplete

MLA Handbook (7^th Edition):

-3704-0597. “Quantitative measurements of ablation-products transport in supersonic turbulent flows using planar laser-induced fluorescence.” 2015. Web. 24 Jan 2021.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Vancouver:

-3704-0597. Quantitative measurements of ablation-products transport in supersonic turbulent flows using planar laser-induced fluorescence. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2015. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/31340.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Council of Science Editors:

-3704-0597. Quantitative measurements of ablation-products transport in supersonic turbulent flows using planar laser-induced fluorescence. [Doctoral Dissertation]. University of Texas – Austin; 2015. Available from: http://hdl.handle.net/2152/31340

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University of Texas – Austin

26. -7892-5500. Variable incidence angle film cooling experiments on a scaled up turbine airfoil model.

Degree: PhD, Mechanical Engineering, 2016, University of Texas – Austin

URL: http://hdl.handle.net/2152/68221

► This study focused on three main areas of research - the development of a new type of low-speed, closed-loop wind tunnel design to test at… (more)

▼ This study focused on three main areas of research - the development of a new type of low-speed, closed-loop wind tunnel design to test at varying incidence angles, the investigation of film cooling for gas turbine components at varying incidence angles, and the analysis of the heat transfer and flow field predictive capability of RANS models. In order to develop the closed loop wind tunnel, a rigorous design and validation process was followed. This validated design is unique for low-speed closed-loop facilities. The development of this wind tunnel enabled measurements of adiabatic and overall effectiveness of two highly realistic airfoil models with shaped holes at varying incidence angles. This was accomplished through application of the appropriate aerodynamic and heat transfer scaling parameters for all measurements. Among other results, it was found that the shaped holes at the stagnation row of holes significantly enhanced film cooling effectiveness in the high curvature region of the showerhead depending on the incidence angle tested, and that the incidence angle effect persisted on the matched Biot number model. No previous studies had experimentally investigated the effects of incidence angle effects on overall effectiveness of a full-coverage airfoil. Furthermore, no previous studies had investigated the effect of shaped holes in the showerhead region of a realistic airfoil model such as the one used in this study. Finally, the computational predictive capability of various RANS turbulence models were analyzed by predicting the heat transfer coefficient of the model as well as the turbulence production and turning angle of a vertical array of rods used to generate turbulence in the tunnel. It was found that the computational predictions of leading-edge heat transfer were under-predicted due to the shape of the model leading edge. It was also found that the SST-Transition model appropriately predicted downstream turbulence and turning angle of the vertical rod array when compared to experimental results and empirical correlations in the literature. This is the first study to experimentally and computationally investigate the turning angle of a vertical grid array over a range of zero and non-zero inlet flow angles. Advisors/Committee Members: Bogard, David G. (advisor), Davidson, Frederick T (committee member), Kohli, Atul (committee member), Ezekoye, Ofodike A. (committee member), Webber, Michael E (committee member).

Subjects/Keywords: Film-cooling; Gas turbine; Low-speed; Wind tunnel; Heat transfer; Incidence angle; Facility design

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APA (6^th Edition):

-7892-5500. (2016). Variable incidence angle film cooling experiments on a scaled up turbine airfoil model. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/68221

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Chicago Manual of Style (16^th Edition):

-7892-5500. “Variable incidence angle film cooling experiments on a scaled up turbine airfoil model.” 2016. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/68221.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

MLA Handbook (7^th Edition):

-7892-5500. “Variable incidence angle film cooling experiments on a scaled up turbine airfoil model.” 2016. Web. 24 Jan 2021.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Vancouver:

-7892-5500. Variable incidence angle film cooling experiments on a scaled up turbine airfoil model. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2016. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/68221.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Council of Science Editors:

-7892-5500. Variable incidence angle film cooling experiments on a scaled up turbine airfoil model. [Doctoral Dissertation]. University of Texas – Austin; 2016. Available from: http://hdl.handle.net/2152/68221

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

University of Texas – Austin

27. -5734-0418. Fire safety in sustainable buildings : status, options, alternatives.

Degree: PhD, Mechanical Engineering, 2017, University of Texas – Austin

URL: http://hdl.handle.net/2152/47453

► Sustainable design is a holistic goal of efficiency and optimization to reduce building energy consumption and environmental impact while improving occupant health and safety. Sustainable… (more)

▼ Sustainable design is a holistic goal of efficiency and optimization to reduce building energy consumption and environmental impact while improving occupant health and safety. Sustainable building construction is one of the fastest growing industries in the United States. Changes in materials, products, designs, and methodologies are occurring to accommodate this green progression. While these changes have energy and environmental benefits, questions have been raised about the impacts on fire safety. As sustainability is rapidly adopted in the building construction industry, so too must our understanding of fire safety implications. It is possible that a single fire event can negate several, if not all, elements of green design. Intermingling green design and fire safety such that they reinforce rather than undermine each other would produce a net benefit to both humans and the environment. Without this consideration, green design could unintentionally increase fire risk and damage. To begin addressing some of these concerns, a three-pronged approach was taken in this research. First, a detailed qualitative examination of the relationship between fire safety and sustainability in buildings was conducted, including a discussion on the status of the fire and sustainability communities and recommendations on areas for development and implementation to promote fire safe sustainable designs. This first analysis concludes that exchange between the sustainability and fire safety communities is inadequate. The fire safety community is focused on quantifying and tracking such implications with a concern for firefighter security and training, while the sustainability community is focused on meeting the minimum building code requirements for fire protection. Second, a quantitative analysis on thermal insulation, an essential building material, was performed to demonstrate the current options available to designers and regulators and, more generally, how to integrate both fire safety and sustainability in material selection. A pointed result of this work is that rockwool, an insulation popular in Europe but rarely used in the United States, consistently ranked as a top performer. In the third component of this work, an investigation into the viability of two alternative, reportedly environmentally benign flame retardants (FRs) was conducted for use on flexible polyurethane foam (PU), a prevalent material in interior furnishings. Several previously unknown characteristics of these unique FRs were discovered through this work, including dissimilarities to a conventional halogenated FR treatment. In summary, this research elucidates the current status of the nexus of fire safety and sustainability, offers an immediate method of selecting preferable material options, and validates sustainable FR alternatives. Advisors/Committee Members: Ezekoye, Ofodike A. (advisor), Webber, Michael E., 1971- (advisor), Ellison, Christopher J. (committee member), Ellzey, Janet L. (committee member).

Subjects/Keywords: Fire safety; Sustainability; Insulation; Green building; Optimization; Flame retardant; Polydopamine; Flexible polyurethane foam; Thermal degradation; Kinetic parameters

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APA (6^th Edition):

-5734-0418. (2017). Fire safety in sustainable buildings : status, options, alternatives. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/47453

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Author name may be incomplete

Chicago Manual of Style (16^th Edition):

-5734-0418. “Fire safety in sustainable buildings : status, options, alternatives.” 2017. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/47453.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

MLA Handbook (7^th Edition):

-5734-0418. “Fire safety in sustainable buildings : status, options, alternatives.” 2017. Web. 24 Jan 2021.

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Vancouver:

-5734-0418. Fire safety in sustainable buildings : status, options, alternatives. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2017. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/47453.

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Author name may be incomplete

Council of Science Editors:

-5734-0418. Fire safety in sustainable buildings : status, options, alternatives. [Doctoral Dissertation]. University of Texas – Austin; 2017. Available from: http://hdl.handle.net/2152/47453

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Author name may be incomplete

University of Texas – Austin

28. Carpenter, Katherine Patricia. Influence of surface chemistry and electric fields on the nucleation of ice and hydrates.

Degree: PhD, Mechanical Engineering, 2016, University of Texas – Austin

URL: http://hdl.handle.net/2152/68268

► Understanding and controlling the formation of ice and hydrates has important energy-related applications including ice mitigation, methane harvesting from hydrates, and desalination by freezing. This… (more)

▼ Understanding and controlling the formation of ice and hydrates has important energy-related applications including ice mitigation, methane harvesting from hydrates, and desalination by freezing. This dissertation describes multiple studies to explore the role of surface chemistry and electric fields on the nucleation of ice and hydrates. The first part of this dissertation describes a study on saltwater ice formation. A majority of the available literature on ice mitigation concerns freshwater icing, unlike this study. This work quantifies the influence of surface chemistry and texture on saltwater ice formation. Two kinds of experiments are conducted as part of this effort. The first set of experiments quantifies the influence of surface chemistry on ice nucleation of various saltwater solutions. It is noted that a large number of individual experiments were conducted, which makes the present results statistically meaningful, unlike most previous studies. The second set of experiments studies the dynamics associated with impact of saltwater droplets on supercooled superhydrophobic surfaces. It is seen that the saltwater droplets retract more than freshwater droplets (after impact). The greater bounciness of saltwater droplets is a result of slower ice nucleation propagation kinetics. These experiments indicate that superhydrophobic surfaces will offer greater resistance to impact icing with saltwater than pure water and can remain useful at temperatures as low as -40 °C. The second part of the dissertation includes a detailed study of electrofreezing, i.e., the electrically induced nucleation of ice from supercooled water. This work studies ice nucleation in electrowetted water droplets, wherein there is no electric field inside the droplet resting on a dielectric layer. Instead, there is an interfacial electric field and charge buildup at the solid-liquid interface. Through carefully planned experiments, the influence of electric fields and electric currents on the freezing temperature elevation is quantified. The results facilitate an in-depth understanding of various mechanisms underlying electrofreezing. Firstly, interfacial electric fields alone can significantly elevate freezing temperatures by more than 15 °C in the absence of current flow. Secondly, electrofreezing-induced temperature elevation saturates at high electric field strengths. Thirdly, the polarity of the interfacial charge does not significantly influence electrofreezing. Finally, current flow can further elevate the nucleation temperature by providing additional triggers for nucleation events. Overall, both the electric field and the electric current influence electrofreezing; however, the physical mechanisms are very different. The third part of the dissertation studies a novel concept to induce rapid formation of hydrates. The long induction times (hours to days) associated with hydrate nucleation is a significant barrier to many hydrate-based applications. The present work shows that electro-nucleation can promote rapid hydrate… Advisors/Committee Members: Bahadur, Vaibhav (advisor), Bogard, David (committee member), Espinoza, David N (committee member), Ezekoye, Ofodike (committee member), Shi, Li (committee member).

Subjects/Keywords: Phase change; Ice formation; Ice nucleation; Electrofreezing; Electro-nucleation; Saltwater; Hydrates

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APA (6^th Edition):

Carpenter, K. P. (2016). Influence of surface chemistry and electric fields on the nucleation of ice and hydrates. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/68268

Chicago Manual of Style (16^th Edition):

Carpenter, Katherine Patricia. “Influence of surface chemistry and electric fields on the nucleation of ice and hydrates.” 2016. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/68268.

MLA Handbook (7^th Edition):

Carpenter, Katherine Patricia. “Influence of surface chemistry and electric fields on the nucleation of ice and hydrates.” 2016. Web. 24 Jan 2021.

Vancouver:

Carpenter KP. Influence of surface chemistry and electric fields on the nucleation of ice and hydrates. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2016. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/68268.

Council of Science Editors:

Carpenter KP. Influence of surface chemistry and electric fields on the nucleation of ice and hydrates. [Doctoral Dissertation]. University of Texas – Austin; 2016. Available from: http://hdl.handle.net/2152/68268

29. Malaya, Nicholas Penha. Numerical simulation of synthetic, buoyancy-induced columnar vortices.

Degree: PhD, Mechanical engineering, 2016, University of Texas – Austin

URL: http://hdl.handle.net/2152/45689

► Much of the solar energy incident on the Earth’s surface is absorbed into the ground, which in turn heats the air layer above the surface.… (more)

Subjects/Keywords: CFD; Scientific computing; Optimization; Dust devils

12 more images…

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

APA (6^th Edition):

Malaya, N. P. (2016). Numerical simulation of synthetic, buoyancy-induced columnar vortices. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/45689

Chicago Manual of Style (16^th Edition):

Malaya, Nicholas Penha. “Numerical simulation of synthetic, buoyancy-induced columnar vortices.” 2016. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/45689.

MLA Handbook (7^th Edition):

Malaya, Nicholas Penha. “Numerical simulation of synthetic, buoyancy-induced columnar vortices.” 2016. Web. 24 Jan 2021.

Vancouver:

Malaya NP. Numerical simulation of synthetic, buoyancy-induced columnar vortices. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2016. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/45689.

Council of Science Editors:

Malaya NP. Numerical simulation of synthetic, buoyancy-induced columnar vortices. [Doctoral Dissertation]. University of Texas – Austin; 2016. Available from: http://hdl.handle.net/2152/45689

University of Texas – Austin

30. -1322-3556. Fuel economy predictions for heavy‐duty vehicles and quasi‐dimensional DI diesel engine numerical modeling.

Degree: PhD, Mechanical Engineering, 2018, University of Texas – Austin

URL: http://hdl.handle.net/2152/68397

► A research team developed the University of Texas Fuel Economy Model to estimate the fuel consumption of both light-duty and heavy-duty vehicles operated on Texas… (more)

▼ A research team developed the University of Texas Fuel Economy Model to estimate the fuel consumption of both light-duty and heavy-duty vehicles operated on Texas roads. One of the objectives of the model was to be as flexible as possible in order to be capable of simulating a variety of vehicles, payloads, and traffic conditions. For heavy-duty vehicles, there are no prescribed driving cycles, there are no coastdown coefficients available from the EPA, and we relied on experimental brake specific fuel consumption maps for a few heavy-duty diesel engines. Heavy-duty vehicle drive cycles highly depend upon the vehicle load, the grade of the road, the engine size, and the traffic conditions. In order to capture real driving conditions 54 drive cycles with three different Class 8 trucks, three weight configurations, three traffic congestion levels, and two drivers are collected. Drive cycles obtained in this research include road grade and vehicle speed data with time. Due to the lack of data from EPA for calculating the road load force for heavy-duty vehicles, coastdown tests were performed. To generate generic fuel maps for the fuel economy model, a direct injection quasi-dimensional diesel engine model was developed based on in-cylinder images available in the literature. Sandia National Laboratory researchers obtained various images describing diesel spray evolution, spray mixing, premixed combustion, mixing controlled combustion, soot formation, and NOx formation via imaging technologies. Dec combined all of the available images to develop a conceptual diesel combustion model to describe diesel combustion from the start of injection up to the quasi-steady form of the jet. The end of injection behavior was left undescribed in this conceptual model because no clear image was available due to the chaotic behavior of diesel combustion. A conceptual end-of-injection diesel combustion behavior model was proposed to capture diesel combustion in its life span. A full-cycle quasi-dimensional direct injection diesel engine model was developed that represents the physical models, utilizing the conceptual model developed from imaging experiments and available experiment-based spray models, of the in-cylinder processes. The compression, expansion, and gas exchange stages are modeled via zero-dimensional single zone calculations. A full cycle simulation is necessary in order to capture the initial conditions of the closed section of the cycle and predict the brake specific fuel consumption accurately. Advisors/Committee Members: Matthews, Ronald D. (advisor), Hall, Matthew John (advisor), Ellzey, Janet L. (committee member), Ezekoye, Ofodike A. (committee member), Biros, George (committee member), Roberts, Charles E. (committee member).

Subjects/Keywords: Quasi-dimensional; Diesel; Engine; Heavy-duty; Direct injection; Numerical; Modeling; Combustion; Coastdown; Drive cycle; Fuel economy; Mathematical; Vehicle; Simulation; Class 8

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

APA (6^th Edition):

-1322-3556. (2018). Fuel economy predictions for heavy‐duty vehicles and quasi‐dimensional DI diesel engine numerical modeling. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/68397

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Author name may be incomplete

Chicago Manual of Style (16^th Edition):

-1322-3556. “Fuel economy predictions for heavy‐duty vehicles and quasi‐dimensional DI diesel engine numerical modeling.” 2018. Doctoral Dissertation, University of Texas – Austin. Accessed January 24, 2021. http://hdl.handle.net/2152/68397.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

MLA Handbook (7^th Edition):

-1322-3556. “Fuel economy predictions for heavy‐duty vehicles and quasi‐dimensional DI diesel engine numerical modeling.” 2018. Web. 24 Jan 2021.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Vancouver:

-1322-3556. Fuel economy predictions for heavy‐duty vehicles and quasi‐dimensional DI diesel engine numerical modeling. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2018. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/2152/68397.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Council of Science Editors:

-1322-3556. Fuel economy predictions for heavy‐duty vehicles and quasi‐dimensional DI diesel engine numerical modeling. [Doctoral Dissertation]. University of Texas – Austin; 2018. Available from: http://hdl.handle.net/2152/68397

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

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