Large Eddy Simulations of Boundary Layer Evolution Under Wall Heat Transfer and Pressure Gradient Conditions

Separated boundary layer under different wall heat transfer and pressure gradient conditions are investigated by using large eddy simulation (LES). The statistic characteristics and the instantaneous flow field of the separated boundary layer under different wall heat transfer conditions are analyzed. The results show that the velocity profile of the separated boundary layer under the cooled isothermal wall condition (the wall temperature being 0.8 times of the inflow temperature) is fuller than that under the adiabatic wall condition. The shape factor of the boundary layer is reduced and the separation bubble is also significantly suppressed. It is also found that the position of the spanwise vortex shedding from separated boundary layers moves upstream under the cooled isothermal wall condition. Moreover, the cooled isothermal wall condition can decrease the frequency of the large scale spanwise vortex rolled-up, and reduce the scales of the spanwise vortex on the separated shear layer, which accelerates the transition process of the separated shear layer and make reattachment point move upstream.