This study focuses on High-Amplitude Wall Heat Flux events (HAWHFs) occurring during the interaction between a supersonic flat-plate Turbulent Boundary Layer (TBL) at a Mach number of 2.25 and an oblique shock wave impinging at 33.2°. A database from a validated direct numerical simulation is analyzed using conditional averaging and a two-dimensional clustering methodology to elucidate the statistical characteristics of both positive and negative HAWHFs within the interaction region. The results reveal that the interaction considerably affects the temporal attributes of the HAWHFs, leading to an extended lifespan for the positive HAWHFs and an increased interval between the occurrences of negative HAWHFs. The structural characteristics of the identified HAWHFs are delineated based on the evolution of population density, aspect ratio, and both absolute and relative distances throughout the interaction. The joint probability density functions of the relative positioning of two adjacent structures indicate that, away from the reattachment point, the positive HAWHFs align in the spanwise direction, displaying similarities with the negative HAWHFs. Moreover, a conditional analysis of flow structures associated with HAWHFs is conducted. This analysis of the conditionally averaged three-dimensional fields reveals that the interaction fosters larger-scale organizational patterns in the downstream region. However, the formation of positive and negative HAWHFs remains largely unaffected by the interaction, with the former predominantly linked to a two-layer temperature structure and the latter primarily associated with a pair of oblique vortices.

This study investigates high-amplitude Extreme Wall Pressure fluctuation Events (EWPEs) in Shock wave/Turbulent Boundary Layer Interactions (STBLIs) through the conditional sampling of direct numerical simulation databases. The aim is to evaluate the effect of STBLIs and their strength on the statistical properties and associated turbulent structures of EWPEs using the conditional-averaging and clustering method. The temporal statistical results show that the occurrence probability and contribution ratio of EWPEs decrease downstream of strong STBLI, but their duration and interval time increase. Regarding two-dimensional wall pressure structures, the large population of small-scale structures becomes more elongated, but strong interactions induce a greater number of large-scale structures. The pairing of wall pressure events with a higher occurrence probability is verified by the joint probability density functions. Conditional analysis reveals that, as the interaction strength increases, the ejection motion associated with positive events occurs farther downstream and the spanwise vortex core locating above negative events is lifted up along the wall-normal direction. Moreover, analysis associates the paired wall pressure events with the sweep, ejection, and swirl motions in STBLIs, where hairpin eddies play an important role in the formation of positive–negative paired wall pressure structures.

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.