Unsteady flow interaction in endwall regions of high-loaded turbine stage

An investigation into the unsteady flow interaction at the endwall region of a high-pressure turbine stage is performed by numerical simulation with a 3D unsteady viscous solver. The article examines the unsteady interaction between stator wakes and rotor passage vortices. The effects of blade loading and shockwaves are also revealed. The results indicate that periodic stator wakes can reduce the radial vorticity of hub passage vortex. The unsteady effects of stator wakes on the streamwise vorticity of hub passage vortex depend on wake distribution. The vorticity decreases if the wakes from the stator suction side have the direction opposite to the streamwise vorticity with hub passage vortex. And the unsteady effects of stator appreciably reduce the rotor blade load near the endwall, which can suppress hub passage vortex development. On the other hand, the trailing edge shock systems of the stator and rotor cause a significant periodic change in the rotor surface pressure field, which is a factor to be considered in design. In addition, by evaluating the entropy increase and entropy generation in the turbine stage, the unsteady losses are investigated quantitatively, which leads to some significant conclusions.