Separation characteristics of shock wave/turbulent boundary layer interaction under the effect of a transverse jet

Abstract

Shock wave/turbulent boundary layer interactions under the effect of a transverse jet at different distances are investigated via large eddy simulation. The instantaneous characteristics of the turbulent boundary layer affected by the jet wake, including near-wall streaks and large-scale vortices, are examined. Separation features are compared and analyzed through three-dimensional separation bubbles and skin frictions. Results show that a far jet can diminish separation and is mainly manifested as the reattachment point moving upstream. When the distance is long enough for the evolution of large-scale vortices, the effects on the spanwise direction are evenly distributed. A near jet has stronger suppression on separation, both the separation point and reattachment point have a significant movement. Due to the insufficient development of the jet wake, the separation bubble shows different characteristics along the spanwise direction. The streamwise Reynolds stress is calculated and investigated carefully. The jet enhances the turbulence intensity at the central line in both the inner and outer layers, while only affecting the intensity at the sideline in the out layer. A conclusion on the movements of the separation point and reattachment point is proposed. The location of the reattachment point is determined by the incident shock and near-wall characteristics of the boundary layer. The location of the separation point is dominated by the turbulent intensity in the outer layer while incident shock is fixed.