NUMERICAL SIMULATION OF A HIGHLY LOADED LPT CASCADE WITH STRONG SUCTION SIDE SEPARATION UNDER PERIODICALLY UNSTEADY INFLOW CONDITIONS

摘要

The effects of periodically unsteady inflow conditions on boundary layer development of a highly loaded low pressure turbine cascade have numerically been studied using an unsteady Reynolds averaged Navier-Stokes solver. The numerical results show good agreement with measurement data by means of time mean profile pressure distribution and unsteady boundary layer development. In particular a reduction of the suction side separation bubble caused by the wakes is well reproduced. For increasing wake passing frequencies this reduction becomes even more pronounced. An independent variation of the flow coefficient reveals that the trajectory of the wake through the blade passage is influenced and velocity disturbances induced by the wake interact more strongly with the boundary layer on the blade as the flow coefficient decreases.