The Experts below are selected from a list of 18 Experts worldwide ranked by ideXlab platform
G. Feldman - One of the best experts on this subject based on the ideXlab platform.
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Progress in Modeling Missile Fuel Venting and Plume Contrail Formation (Postprint)
2020Co-Authors: J. D. Chenoweth, G. Feldman, Kevin Brinckman, J. J. York, Sanford DashAbstract:Abstract : In this paper, we discuss progress made in extending specialized missile plume codes to analyze more generalized problems entailing varied missile propulsive flow field phenomena. Problems of interest include those of Fuel Venting and plume contrail formation. To analyze such processes, gas/liquid modeling is being incorporated that includes primary and secondary breakup, and vaporization/condensation physics. This is being performed at an engineering level and overall progress in extending plume codes to analyze these processes will be described. Exemplary problems described include those of both gaseous and liquid Fuel Venting, application of unified secondary breakup and vaporization of a liquid Fuel Venting problem, and, contrail formation in a generic missile plume.
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A CFD Methodology for Liquid Jet Breakup and Vaporization Predictions of Compressible Flows
46th AIAA Aerospace Sciences Meeting and Exhibit, 2008Co-Authors: Kevin Brinckman, Sanford Dash, Ashvin Hosangadi, Vineet Ahuja, G. FeldmanAbstract:A robust computational fluid dynamics methodology for simulating liquid jet discharge and breakup in high-speed gas/liquid flows is being developed for use in practical engineering applications. The proposed approach is cast within a RANS framework and utilizes a volume-of-fluid type (VOF) methodology to efficiently capture the gas/liquid interface location. Relevant physics are modeled to predict liquid atomization/vaporization through a cascading process involving interface surface breakup, primary droplet formation, and droplet secondary breakup and vaporization. The current VOF approach is well suited for applications involving liquid jet discharge at lower ambient pressures, such as liquid Fuel Venting, gas-turbine Fuel injection, or atmospheric bulk-dispense problems, where the liquid behavior is essentially incompressible making the numerical solution more difficult in a compressible flow environment. In place of a traditional VOF approach with different thermodynamic treatments of gas and liquid, a unified, multi-phase thermodynamic framework is used which is applicable to both the gas and liquid phases. Density-based fluid dynamic equations are transformed to a “quasi-pressure-based” form, and preconditioning is used which facilitates integrating the equations with widely disparate sound speeds. This approach is implemented in the structured grid code CRAFT CFD, as well as the multi-element unstructured grid code, CRUNCH CFD, permitting grid adaptation to be applied to enhance efficient gas-liquid interface tracking. In order to avoid resolving the liquid surface breakup numerically, a surface breakup model is applied with correlations for droplet formation based on local shear and surface tension across the gas/liquid interface, allowing the size of the droplets generated to vary spatially as well as in time with the local evolution of the gas/liquid interface. These primary droplets are transferred to an Eulerian dispersed phase where they are subject to secondary breakup and vaporization. Several solutions of exemplary problems are presented.
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Progress in Modeling Missile Fuel Venting and Plume Contrail Formation
45th AIAA Aerospace Sciences Meeting and Exhibit, 2007Co-Authors: J. D. Chenoweth, G. FeldmanAbstract:In this paper, we discuss progress made in extending specialized missile plume codes to analyze more generalized problems entailing varied missile propulsive flowfield phenomena. Problems of interest include those of Fuel Venting and plume contrail formation. To analyze such processes, gas/liquid modeling is being incorporated that includes primary and secondary breakup, and vaporization/condensation physics. This is being performed at an engineering level and overall progress in extending plume codes to analyze these processes will be described. Exemplary problems described include those of both gaseous and liquid Fuel Venting, application of unified secondary breakup and vaporization of a liquid Fuel Venting problem, and, contrail formation in a generic missile plume.
J. D. Chenoweth - One of the best experts on this subject based on the ideXlab platform.
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Progress in Modeling Missile Fuel Venting and Plume Contrail Formation (Postprint)
2020Co-Authors: J. D. Chenoweth, G. Feldman, Kevin Brinckman, J. J. York, Sanford DashAbstract:Abstract : In this paper, we discuss progress made in extending specialized missile plume codes to analyze more generalized problems entailing varied missile propulsive flow field phenomena. Problems of interest include those of Fuel Venting and plume contrail formation. To analyze such processes, gas/liquid modeling is being incorporated that includes primary and secondary breakup, and vaporization/condensation physics. This is being performed at an engineering level and overall progress in extending plume codes to analyze these processes will be described. Exemplary problems described include those of both gaseous and liquid Fuel Venting, application of unified secondary breakup and vaporization of a liquid Fuel Venting problem, and, contrail formation in a generic missile plume.
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Progress in Modeling Missile Fuel Venting and Plume Contrail Formation
45th AIAA Aerospace Sciences Meeting and Exhibit, 2007Co-Authors: J. D. Chenoweth, G. FeldmanAbstract:In this paper, we discuss progress made in extending specialized missile plume codes to analyze more generalized problems entailing varied missile propulsive flowfield phenomena. Problems of interest include those of Fuel Venting and plume contrail formation. To analyze such processes, gas/liquid modeling is being incorporated that includes primary and secondary breakup, and vaporization/condensation physics. This is being performed at an engineering level and overall progress in extending plume codes to analyze these processes will be described. Exemplary problems described include those of both gaseous and liquid Fuel Venting, application of unified secondary breakup and vaporization of a liquid Fuel Venting problem, and, contrail formation in a generic missile plume.
Sanford Dash - One of the best experts on this subject based on the ideXlab platform.
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Progress in Modeling Missile Fuel Venting and Plume Contrail Formation (Postprint)
2020Co-Authors: J. D. Chenoweth, G. Feldman, Kevin Brinckman, J. J. York, Sanford DashAbstract:Abstract : In this paper, we discuss progress made in extending specialized missile plume codes to analyze more generalized problems entailing varied missile propulsive flow field phenomena. Problems of interest include those of Fuel Venting and plume contrail formation. To analyze such processes, gas/liquid modeling is being incorporated that includes primary and secondary breakup, and vaporization/condensation physics. This is being performed at an engineering level and overall progress in extending plume codes to analyze these processes will be described. Exemplary problems described include those of both gaseous and liquid Fuel Venting, application of unified secondary breakup and vaporization of a liquid Fuel Venting problem, and, contrail formation in a generic missile plume.
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A CFD Methodology for Liquid Jet Breakup and Vaporization Predictions of Compressible Flows
46th AIAA Aerospace Sciences Meeting and Exhibit, 2008Co-Authors: Kevin Brinckman, Sanford Dash, Ashvin Hosangadi, Vineet Ahuja, G. FeldmanAbstract:A robust computational fluid dynamics methodology for simulating liquid jet discharge and breakup in high-speed gas/liquid flows is being developed for use in practical engineering applications. The proposed approach is cast within a RANS framework and utilizes a volume-of-fluid type (VOF) methodology to efficiently capture the gas/liquid interface location. Relevant physics are modeled to predict liquid atomization/vaporization through a cascading process involving interface surface breakup, primary droplet formation, and droplet secondary breakup and vaporization. The current VOF approach is well suited for applications involving liquid jet discharge at lower ambient pressures, such as liquid Fuel Venting, gas-turbine Fuel injection, or atmospheric bulk-dispense problems, where the liquid behavior is essentially incompressible making the numerical solution more difficult in a compressible flow environment. In place of a traditional VOF approach with different thermodynamic treatments of gas and liquid, a unified, multi-phase thermodynamic framework is used which is applicable to both the gas and liquid phases. Density-based fluid dynamic equations are transformed to a “quasi-pressure-based” form, and preconditioning is used which facilitates integrating the equations with widely disparate sound speeds. This approach is implemented in the structured grid code CRAFT CFD, as well as the multi-element unstructured grid code, CRUNCH CFD, permitting grid adaptation to be applied to enhance efficient gas-liquid interface tracking. In order to avoid resolving the liquid surface breakup numerically, a surface breakup model is applied with correlations for droplet formation based on local shear and surface tension across the gas/liquid interface, allowing the size of the droplets generated to vary spatially as well as in time with the local evolution of the gas/liquid interface. These primary droplets are transferred to an Eulerian dispersed phase where they are subject to secondary breakup and vaporization. Several solutions of exemplary problems are presented.
James Raymond Smith - One of the best experts on this subject based on the ideXlab platform.
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para h2 to ortho h2 conversion in a full scale automotive cryogenic pressurized hydrogen storage up to 345 bar
International Journal of Hydrogen Energy, 2014Co-Authors: Guillaume Petitpas, Salvador M Aceves, Manyalibo J Matthews, James Raymond SmithAbstract:Abstract Hydrogen vehicles offer the potential to improve energy independence and lower emissions but suffer from reduced driving range. Cryogenic pressure vessel storage (also known as cryo-compressed storage) offers the advantage of higher densities than room temperature compressed although it has the disadvantage of cryogenic operating temperatures which results in boil-off when the temperature of the gas increases. In order to understand and optimize the time prior to boil-off, we have examined heat absorption from the transition between the two quantum states of the hydrogen molecule (para–ortho) in a full-scale (151 L internal volume) automotive cryogenic pressure vessel at pressures and temperatures up to 345 bar and 300 K, and densities between 14 and 67 g/L (2.1–10.1 kg H2). The relative concentration of the two species was measured using rotational Raman scattering and verified by calorimetry. In fifteen experiments spanning a full year, we repeatedly filled the vessel with saturated LH2 at near ambient pressure (2–3 bar), very low temperatures (20.3–25 K), varying densities, and very high para-H2 fraction (99.7%). We subsequently monitored vessel pressure and temperature while performing periodic ortho-H2 concentration measurements with rotational Raman scattering as the vessel warmed up and pressurized due to environmental heat entry. Experiments show that para–ortho H2 conversion typically becomes active after 10–15 days of dormancy (“initiation” stage), when H2 temperature reaches 70–80 K. Para–ortho H2 conversion then approaches completion (equilibrium) in 25–30 days, when the vessel reaches 100–120 K at ∼50 g/L density. Warmer temperatures are necessary for conversion at lower densities, but the number of days remains unchanged. Vessel dormancy (time that the vessel can absorb heat from the environment before having to vent Fuel to avoid exceeding vessel rating) increased between 3 and 7 days depending on hydrogen density, therefore indicating a potentially large benefit for reduced Fuel Venting in cryogenic pressurized hydrogen storage.
Guillaume Petitpas - One of the best experts on this subject based on the ideXlab platform.
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para h2 to ortho h2 conversion in a full scale automotive cryogenic pressurized hydrogen storage up to 345 bar
International Journal of Hydrogen Energy, 2014Co-Authors: Guillaume Petitpas, Salvador M Aceves, Manyalibo J Matthews, James Raymond SmithAbstract:Abstract Hydrogen vehicles offer the potential to improve energy independence and lower emissions but suffer from reduced driving range. Cryogenic pressure vessel storage (also known as cryo-compressed storage) offers the advantage of higher densities than room temperature compressed although it has the disadvantage of cryogenic operating temperatures which results in boil-off when the temperature of the gas increases. In order to understand and optimize the time prior to boil-off, we have examined heat absorption from the transition between the two quantum states of the hydrogen molecule (para–ortho) in a full-scale (151 L internal volume) automotive cryogenic pressure vessel at pressures and temperatures up to 345 bar and 300 K, and densities between 14 and 67 g/L (2.1–10.1 kg H2). The relative concentration of the two species was measured using rotational Raman scattering and verified by calorimetry. In fifteen experiments spanning a full year, we repeatedly filled the vessel with saturated LH2 at near ambient pressure (2–3 bar), very low temperatures (20.3–25 K), varying densities, and very high para-H2 fraction (99.7%). We subsequently monitored vessel pressure and temperature while performing periodic ortho-H2 concentration measurements with rotational Raman scattering as the vessel warmed up and pressurized due to environmental heat entry. Experiments show that para–ortho H2 conversion typically becomes active after 10–15 days of dormancy (“initiation” stage), when H2 temperature reaches 70–80 K. Para–ortho H2 conversion then approaches completion (equilibrium) in 25–30 days, when the vessel reaches 100–120 K at ∼50 g/L density. Warmer temperatures are necessary for conversion at lower densities, but the number of days remains unchanged. Vessel dormancy (time that the vessel can absorb heat from the environment before having to vent Fuel to avoid exceeding vessel rating) increased between 3 and 7 days depending on hydrogen density, therefore indicating a potentially large benefit for reduced Fuel Venting in cryogenic pressurized hydrogen storage.
