Verification and Validation for Laminar Hypersonic Flowfields

摘要

The accuracy .of Mach 8 laminar flow solutions over a spherical y-blunted cone isverified, and the various physical models are validated. Verification of the solution accuracy is demonstrated by monitoring iterative convergence, performing a comprehensive grid convergence study, comparison to benchmark inviscid results, and code-to-code comparisons. Although the numerical scheme is nominally second order accurate in space, the presence of first order accuracy at the shock discontinuity results in first order behavior for the surface pressure distributions as the grid is sufficiently refined. Alternative methods are proposed for analyzing the spatial convergence behavior and determining the order of accuracy for mixed first and second order schemes. Validation of the computational model is performed via surface pressure comparisons with high-quality experimental data. Careful attention is paid to the assumptions in the computational and experimental modeling. In particular, the thermodynamic state of the hypersonic wind tunnel nozzle is examined and arguments are made for the presence of a significant amount of thermal nonequilibrium. Bias errors in the experimental Mach number calibration are discussed which are related to the assumption of thermal equilibrium (minus 0.23 percent) and the averaging of probe data over the entire test section (plus 0.6 percent). Differences between the