Velocity Slip and Temperature Jump in Hypersonic Aerothermodynamics

摘要

Hypersonic vehicles experience different flow regimes during flight due to changes in atmospheric density. Computational Fluid Dynamics (CFD), while relatively computationally inexpensive, are not physically accurate in areas of highly non-equilibrium flows. The direct simulation Monte Carlo (DSMC) method, while physically accurate for all flow regimes, is relatively computationally expensive. A breakdown parameter can be used to determine where in the flow domain the CFD methods are valid. The current study investigates the effect of continuum breakdown on surface aerothermodynamic properties (pressure, shear stress and heat transfer rate) of a cylinder in Mach 10 and Mach 25 flows of argon gas for several different flow regimes, from the continuum to a rarefied gas. Several different velocity slip and temperature jump boundary conditions are examined for use with the CFD method. CFD and DSMC solutions are obtained at each condition. Total drag and peak heat transfer rate predictions by CFD remains within about 6% of the DSMC predictions for all regimes considered, with the generalized slip condition proposed by Gokcen giving the best results.