Direct numerical simulation of hypersonic cone-flare model at angle of attack

A direct numerical simulation of a hypersonic 7°-34° cone-flare model at an angle of attack is carried out. By comparing the flow characteristics on 0°, 90° and 180° sections, we evaluate the effect of crossflow on shock wave and boundary layer interaction in terms of the distribution of wall pressure, skin friction and heat transfer, the unsteady motion of the separation bubble, and the evolution of the reattached boundary layer. It is found that the flow separation occurs near the corner, and the interaction of the shock wave and boundary layer in the crossflow and windward region leads to a significant increase in wall pressure, skin friction, and heat transfer. The ratio of heat transfer to pressure exhibits a rise in the interaction region, followed by a drop caused by the reattachment, while the Reynolds analogy is completely invalid in the separation zone. Low-frequent unsteady expansion/contraction motion of the separation bubble is revealed through spectral analysis of the bubble area fluctuation. It is closely related to the low frequency shock wave oscillation in the crossflow region; however, hysteresis occurs in the windward region while is irrelevant in the leeward region. Based on the proper orthogonal decomposition results of the velocity fluctuation field, the separation region is related to large-scale structures near the shear layer in the low-order modes. The evolution of the reattached boundary layer shows the drastic Reynolds stress increase in vicinity of the reattachment point caused by the angle of attack, with the streamwise component recovering rapidly. Meanwhile, the peak location of Reynolds stress components continues to move outward in the leeward region, and has rapidly recovered to the inner layer in the windward region and the crossflow region. In addition, the distribution of Reynolds stress anisotropy invariants further indicates that the peak value of the turbulence anisotropy in the near-wall region downstream of the interaction is weaker in the leeward region than in the windward region.