ACCURATE COMPUTATIONS OF HYPERSONIC FLOWS USING AUSMPW+ SCHEME AND SHOCK-ALIGNED GRID TECHNIQUE

There are two problems in computation of hypersonic flow. One is the inaccuracy of the physical modeling and the other is an error due to inaccurate numerical dissipation. Until now the distribution of species can not calculate accurately in the region of the strong interaction between vibration and chemical reaction. The computation in large expansion region such as nozzle is also inaccurate due to the inaccurate reaction rate coefficient. From the view of numerical difficulty, a stiff pressure discontinuity may cause large numerical oscillations and degenerate robustness and convergence. Numerical dissipation is especially sensitive in boundary layer since it can easily contaminate physical viscosity, leading to the inaccurate resolution of skin friction or heat transfer coefficients. In this paper we focus on the issue of numerical discretization. A newly improved scheme of AUSMPW, so called AUSMPW+, and ShockAligned Grid Technique (SAGT) are proposed for an accurate computation of hypersonic flows. Compared to AUSMPW, AUSMPW+ scheme is more efficient to implement while it maintains the same level of robustness and accuracy in capturing the stiff pressure discontinuity or boundary layer. SAGT combined with AUSMPW+ can capture the oblique shock as well as the normal shock with little numerical dissipation.