Large eddy simulations of shock-boundary layer interactions in supersonic turbine cascades with adiabatic and isothermal walls

Large eddy simulations are employed to investigate the flow in a supersonic turbine cascade with adiabatic and cooled walls. The inlet Mach number is set as 2.0, and the Reynolds number based on the inlet velocity and axial chord is 200,000. For the isothermal case, the ratio of wall to inlet temperatures is 0.75. The effects of wall cooling on the shock-boundary layer interaction are evaluated through flow visualization and spectral analysis. The results indicate that the impinging shock penetrates deeper in the boundary layer for the cooled wall setup due to the displacement of the sonic line towards the wall. This, in turn, leads to a smaller suction side separation bubble. For the adiabatic case, strong heating effects are observed within the separation bubble, while higher temperatures are observed along the free shear layer downstream the bubble when cooling is applied. An analysis of the unsteadiness of the separation bubbles shows that their breathing patterns are similar, independently of the thermal conditions. Finally, the spectral characteristics of the separation bubbles and shock systems are also investigated.