Prediction for the Separation Length of Two-Dimensional Sonic Injection with High-Speed Crossflow

Abstract

The separation length is an important parameter of transverse jet interaction, which is related to the interaction force, moment, and heating effect. Two-dimensional sonic injection normal to high-speed flow with a turbulent boundary layer is numerically investigated, and the upstream separation length is theoretically predicted. Present numerical study indicates that the separation length is constant as the Mach number increases when the unit Reynolds number is fixed at a range of to for the Mach number greater than 3.50 and smaller than 6.50. Results also indicate that the separation length increases with increasing pressure ratio or increasing slot width as well as decreasing Reynolds number. Based on the high Mach number independence of the separation length and effects of other parameters on the separation length, a combination parameter is proposed and then a theoretical model for the separation length is established. This model can be applied to a wide range of pressure ratios, Reynolds numbers, slot widths, and Mach numbers when the Mach number is greater than 3.50. Upstream separation lengths predicted by the present model are compared with experimental and numerical results, as well as results by the existing model. Results show that separation lengths predicted by the present model agree well with experimental and numerical studies.