Direct numerical simulation of hypersonic boundary layer transition over a lifting body at different angles of sideslip

Hypersonic boundary layer transition on a hypersonic transition research vehicle model lifting body by direct numerical simulations under typical hypersonic conditions is investigated. The simulations analyze the model at three angles of sideslip: 0°, 2°, and 4°. The freestream Mach number is 6, the unit Reynolds number is 1×10−7m−1, with a fixed 2° angle of attack. The result indicates that asymmetric transition occurs on the lifting body's surface between the sideslip windward and leeward sides, due to the side incoming flow. Five distinct transition regions are identified: the shoulder crossflow-vortex region, the shoulder vortex region, the lower surface vortex region, the lower surface crossflow region, and the top crossflow-vortex region. The shoulder crossflow-vortex region (windward) shows forward-shifting transition and expanding ranges as the angle of sideslip increases, with two different modes in the head of transition. The transition of the shoulder vortex region (leeward) moves forward and shifts spanwisely toward the attachment line; at the angle of sideslip of 4°, the transition mode induced by the secondary instability of the stationary crossflow occurs. In the lower surface vortex region, transition moves forward, accompanied by localized turbulence spots and altered disturbance patterns at the high angle of sideslip. The lower surface crossflow-vortex (windward) region exhibits a transition region including two zones, while lower surface crossflow-vortex region (leeward) dissipates. The top crossflow-vortex region experiences intensified crossflow effects and localized turbulence spots as the angle of sideslip increases, with the appearance of the distinct topline similar to the attachment line.