Direct numerical simulation of a supersonic turbulent boundary layer over a compression-decompression corner

A direct numerical simulation of the interaction between a shock wave and the supersonic turbulent boundary layer in a compression-decompression corner with a fixed 24 degrees deflection angle at Mach 2.9 is conducted. The characteristics of the shock interactions are investigated for two heights between the compression and decompression corners, corresponding to H / delta ref = 4.25 , 1.22, where delta (ref) denotes the reference turbulent boundary layer thickness. A classic shock wave/turbulent boundary layer interaction flow is reproduced in the higher case. For the lower case, the size of the separation region is significantly decreased, and the low-frequency unsteadiness is slightly suppressed in the interaction region, as assessed by analyzing the mean and fluctuating wall pressure. Flow patterns near the reattachment line show the existence of the Gortler vortices. By analyzing the curvature radius and Gortler number distribution, it was found that a strong centrifuge instability is reserved in the compression corner region and reversed in the decompression corner region due to the convex streamline curvature. The downstream flow of the decompression corner is relatively complex where the additional shocklet and new streamwise vortices are observed. A negative response mechanism is found regarding fluctuating wall-pressure signatures between the upstream and downstream of the decompression corner.

Automated summary

The study investigates the interaction between a shock wave and supersonic turbulent boundary layer in a compression-decompression corner, finding that classic flow characteristics are reproduced in the higher case, while the lower case shows reduced separation and suppressed instability. Flow patterns near the reattachment line reveal Gortler vortices, and a negative response mechanism is observed between fluctuating wall pressures upstream and downstream of the decompression corner.