TY - GEN
T1 - Application of ab-initio based grouped rates for modeling non-equilibrium flow physics
AU - Sharma, Maitreyee P.
AU - Venturi, Simone
AU - Munafò, Alessandro
AU - Panesi, Marco
N1 - The authors were supported by the Air Force Office of Scientific Research Young Investigators Program FA9550-15-1-0132 with Program Officer Dr. Ivett Leyva. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the AFOSR or the US government.
PY - 2019
Y1 - 2019
N2 - This work focuses on the use of ab-initio grouped rates obtained from the CG-QCT method and analytical expressions to model non-equilibrium chemical processes in hypersonic flows. The groups are made by dividing the energy spectrum of the molecule into equal energy intervals. The reduced order framework is derived from the multi-group maximum entropy model using a linear reconstruction function. This paper focuses on three different system of molecules which are of interest during reentry into Earth’s atmosphere: (i) (Formula Presented) �collisions, (ii) (Formula Presented) and (Formula Presented) collisions and (iii) (Formula Presented). The grouped rates for the nitrogen systems are obtained using the CG-QCT method considering the full set of ro-vibrational levels of nitrogen molecule whereas analytical expressions are used to compute the grouped rates for the oxygen system. The reduced order model is used in conjunction with CFD codes to predict the non-equilibrium behavior of high speed flows in one and two dimensions. Two different testcases are considered: (i) one-dimensional nozzle flow and (iii) two-dimensional axi-symmetric flow over a sphere. The results are compared to the state-to-state simulation for the oxygen case since we have the state-to-state rates available for vibrational specific processes. We achieve good agreement with the state-to-state results for the non-equilibrium distributions. The strong state of non-equilibrium observed in the results lays emphasis on the need for computationally efficient models to simulated these high-enthalpy flows.
AB - This work focuses on the use of ab-initio grouped rates obtained from the CG-QCT method and analytical expressions to model non-equilibrium chemical processes in hypersonic flows. The groups are made by dividing the energy spectrum of the molecule into equal energy intervals. The reduced order framework is derived from the multi-group maximum entropy model using a linear reconstruction function. This paper focuses on three different system of molecules which are of interest during reentry into Earth’s atmosphere: (i) (Formula Presented) �collisions, (ii) (Formula Presented) and (Formula Presented) collisions and (iii) (Formula Presented). The grouped rates for the nitrogen systems are obtained using the CG-QCT method considering the full set of ro-vibrational levels of nitrogen molecule whereas analytical expressions are used to compute the grouped rates for the oxygen system. The reduced order model is used in conjunction with CFD codes to predict the non-equilibrium behavior of high speed flows in one and two dimensions. Two different testcases are considered: (i) one-dimensional nozzle flow and (iii) two-dimensional axi-symmetric flow over a sphere. The results are compared to the state-to-state simulation for the oxygen case since we have the state-to-state rates available for vibrational specific processes. We achieve good agreement with the state-to-state results for the non-equilibrium distributions. The strong state of non-equilibrium observed in the results lays emphasis on the need for computationally efficient models to simulated these high-enthalpy flows.
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U2 - 10.2514/6.2019-0792
DO - 10.2514/6.2019-0792
M3 - Conference contribution
AN - SCOPUS:85083943783
SN - 9781624105784
T3 - AIAA Scitech 2019 Forum
BT - AIAA Scitech 2019 Forum
PB - American Institute of Aeronautics and Astronautics Inc, AIAA
T2 - AIAA Scitech Forum, 2019
Y2 - 7 January 2019 through 11 January 2019
ER -