Comparison of Shock-Boundary Layer Interactions in Adiabatic and Isothermal Supersonic Turbine Cascades

TL;DR

This study uses large eddy simulations to compare shock-boundary layer interactions in adiabatic and cooled supersonic turbine cascades, revealing differences in separation bubble behavior and turbulence characteristics due to wall temperature effects.

Contribution

It provides new insights into how wall cooling influences shock-boundary layer interactions and turbulence in supersonic turbine cascades.

Findings

Separation bubbles are smaller and shift downstream with cooling.

Cooling causes the shock to move closer to the blade surface.

Wall-normal turbulence stresses are higher in cooled conditions.

Abstract

Wall-resolved large eddy simulations are employed to investigate the shock-boundary layer interactions (SBLIs) in a supersonic turbine cascade. An analysis of the suction side separation bubbles forming due to the SBLIs is presented for adiabatic and isothermal (cooled) walls. Flow snapshots indicate that the separation bubble contracts and expands in a similar fashion for both thermal boundary conditions. However, the skin-friction coefficient distributions reveal a downstream displacement of the separation region when cooling is applied. The separation bubble is also smaller for this setup compared to the adiabatic one. A steeper pressure rise is observed for the isothermal wall downstream of the incident oblique shock, and this occurs because the incident shock wave gets closer to the blade surface when cooling is applied. The Reynolds stresses are computed to investigate the effects of wall temperature on the turbulence activity. While the levels of the tangential stresses are similar for the cases analyzed, those for the wall-normal component are higher for the cooled wall.