Role of State-to-State Kinetics in Determining Transport Coefficients forHypersonic Flow Simulations

摘要

A numerical study is performed to assess the influence of thermochemical nonequilibrium on the transportcoefficients used in Computational Fluid Dynamics (CFD) simulations of hypersonic external flowfields. An quantitativeassessment is made of transport coefficients from simplified methods of Blottner curve fits and Variable Hard Sphere(VHS) model on the numerical solution of a Mach 23 flow past a sphere cone, the RAMC-II test case. The equationsderived by Kustova [1] in the state kinetic approach for calculating transport coefficients from the Chapman-Enskogsolution of the Wang-Chang Uhlenbeck equation were used to conduct a parametric study for assessment of the effect ofthe following parameters on the state-specific diffusion coefficients: (1) Widely different population distributions,(2) Atomic mass concentration, and (3) Binary atomic to molecular diffusion coefficient ratio. The present study is a firststep to quantify the relative importance of the parameters considered for a future implementation of the computationallyexpensive state-kinetic transport coefficients in multi-dimensional fluid dynamic flow solvers for flow conditions wherethe more general state kinetic approach becomes necessary.