Heat transfer and wall temperature effects in shock wave turbulent boundary layer interactions

TL;DR

This study uses direct numerical simulations to explore how wall temperature variations influence shock wave turbulent boundary layer interactions at Mach 2.28, revealing effects on separation, heat transfer, and turbulence behavior.

Contribution

It provides new insights into the impact of wall temperature on shock-boundary layer interactions, highlighting the effects on flow separation, heat transfer, and turbulence amplification.

Findings

Cooling reduces interaction scales and separation bubble size.

Heating causes expansion of the interaction region.

Maximum heat transfer occurs with cold walls.

Abstract

Direct numerical simulations are carried out to investigate the effect of the wall temperature on the behavior of oblique shock-wave/turbulent boundary layer interactions at freestream Mach number $2.28$ and shock angle of the wedge generator $\varphi = 8^{\circ}$. Five values of the wall-to-recovery-temperature ratio ($T_w/T_r$) are considered, corresponding to cold, adiabatic and hot wall thermal conditions. We show that the main effect of cooling is to decrease the characteristic scales of the interaction in terms of upstream influence and extent of the separation bubble. The opposite behavior is observed in the case of heating, that produces a marked dilatation of the interaction region. The distribution of the Stanton number shows that a strong amplification of the heat transfer occurs across the interaction, and the maximum values of thermal and dynamic loads are found in the case of cold wall. The analysis reveals that the fluctuating heat flux exhibits a strong intermittent behavior, characterized by scattered spots with extremely high values compared to the mean. Furthermore, the analogy between momentum and heat transfer, typical of compressible, wall-bounded, equilibrium turbulent flows does not apply for most part of the interaction domain. The pre-multiplied spectra of the wall heat flux do not show any evidence of the influence of the low-frequency shock motion, and the primary mechanism for the generation of peak heating is found to be linked with the turbulence amplification in the interaction region.