Simulation of Transient Dynamics of Shock Wave Boundary Layer Interactions Using Hybrid Large-Eddy/Reynolds-Averaged Navier-Stokes Models; Final rept. 15 Jul 2006-14 Apr 2007

摘要

Simulations of the Mach 5 compression-corner shock / turbulent boundary layer interaction experimentally mapped by Prof. David Dolling and co- workers have been performed using a hybrid large-eddy / Reynolds-averaged Navier-Stokes (LES/RANS) model. The model captures the mean-flow structure of the interaction reasonably well, with observed deficiencies traced to an under prediction of the displacement effects of the shock-induced separation region. The computational results provide some support for a recent theory relating to the underlying causes of low-frequency shock wave oscillation. The simulation results indicate that the sustained presence of a collection of neighboring streaks of low / high momentum fluid within the boundary layer induces a low frequency undulation of the separation front. Power spectra obtained at various streamwise stations are in good agreement with experimental results, indicating that the LES/RANS method is capable of predicting both the low and high- frequency dynamics of the interaction. Downstream of re-attachment, the simulations capture a three-dimensional mean flow structure, dominated by counter-rotating vortices that produce wide variations in the surface skin friction. Predictions of the structure of the re-attaching boundary layer agree well with experimental pitot pressure measurements. In comparison with Reynolds- averaged model predictions, the LES/RANS model predicts more amplification of Reynolds stresses and a broadening of the Reynolds-stress distribution within the boundary layer that is probably due to re-attachment shock motion.