Study on the separation in the shock wave/boundary layer interaction induced by a curved fin

Abstract

The effect of an isentropic compression wave fan on shock wave/turbulent boundary layer interaction induced by a curved fin is studied by the nanoparticle-based planar laser scattering method, oil flow method, and numerical method. The curved fin consists of two parts: A curved surface generating an isentropic compression fan and a planar surface ensuring the compression fan focuses into a swept shock wave. The flowfield is compared with the three-dimensional separation flowfield induced by a planar fin with the same deflection angle. The results show that the compression fan can compress the turbulent boundary layer without separation, while the focused swept shock wave drives the whole turbulent boundary layer to separate. The flat plate turbulent boundary layer beside the fin is mainly rolled into the separation vortex. The focused swept shock wave adjusts the separation zone to be quasi-conical, suggesting that the quasi-conical separation is the nature of the flowfield in which a turbulent boundary layer interacts with a swept shock wave. The isentropic compression part of the curved fin can prevent the secondary separation of the planar swept shock wave/turbulent boundary layer interaction by changing the attachment process. Based on the focus point of the compression wave fan, the equivalent apex of the curved fin is proposed. The area and intensity of the separation vortex induced by the curved fin are nearly linear as those in the planar fin interaction flowfield. However, the area of the separation vortex induced by the curved fin is larger. The intensity growth of the vortex caused by the curved fin is slower than that of the planar fin.