Numerical study on flow structure and loss of large expansion ratio transonic turbine

The loss features of a typical large expansion ratio transonic turbine and the effects of two trailing edge cooling methods, including trailing edge ejection and pressure side ejection, on losses are investigated by numerical method. It can be found that most of the loss is profile loss which is about 65% of total loss and shock wave loss is the main source of profile loss. For the trailing edge ejection, the pressure at base region arises because of the coolant ejection which leads to decrease of the flow acceleration caused by the expansion wave. Thus the Mach number and shock wave loss are decreased. For the pressure side ejection, the trailing edge shock system is changed and the original shock wave is split into two or more than two weak shock waves which result in the decrease of shock wave loss. Both of the two trailing edge cooling methods are beneficial to reduce the shock wave loss of transonic turbine with large expansion ratio, but the pressure side ejection is more effective.