Flow Similarity in Compressible Convex-Corner Flows

摘要

Boundary-layer flow in the vicinity of a sharp corner has been investigated by many researchers. However, there are limited works done on compressible convex-corner flows. This paper proposes a scaling parameter to characterize the transition from subsonic to transonic expansion flows, incipient shock-induced boundary-layer separation, and separation length. It was found that the flow expansion near the corner apex and peak pressure fluctuations in the recompression process could be scaled linearly with β(<13) for subsonic expansion flows and initial transonic expansion flows. Once the local Mach number exceeded the critical Mach number, the increment of (p_w/p_o)_(min) with β(≈ 13—20) became less significant. For the test cases of extensive shock-induced boundary-layer separation (β > 20), the highly intermittent wall-pressure signals due to shock excursion phenomena resulted in intense pressure fluctuations in the recompression process. However, the amplitude of (σ_p/Pσw)_(max) was roughly a constant value once the separation is sufficiently strong. In summary, β can be used as a flow similarity parameter to categorize the three flow regimes of compressible convex-corner flows with M = 0.34 to 0.89.