Effects of Continuum Breakdown on Hypersonic Aerothermodynamics

摘要

Hypersonic vehicles experience different flow regimes during flight due to changes in atmospheric density. Hybrid Computational Fluid Dynamics (CFD) and Direct Simulation Monte Carlo (DSMC) methods are developed to simulate the flow in different hypersonic regimes. These methods use a breakdown parameter to determine regions of the flow where the CFD physics are no longer valid. The current study investigates the effect of continuum breakdown on surface properties, such as pressure, shear stress and heat transfer rate, on a cylinder in a Mach 10 flow of argon gas for several different flow regimes, from the continuum to a rarefied gas. The difference in total drag ranges from 0.5% for a continuum to 26.2% for a rarefied gas. Peak heat transfer rate differences range from nearly 4% for a continuum to almost 32% for a rarefied gas. Drag depends primarily on continuum breakdown in the wake, while heat transfer rate appears to depend primarily on continuum breakdown in the shock and differences in thermal boundary layer thickness.