CONTROL OF THE UNSTEADY-FLOW IN A STATOR BLADE ROW INTERACTING WITH UPSTREAM MOVING WAKES

A computational approach, based on a spectral-element Navier-Stokes solver, has been applied to the study of the unsteady flow arising from wake-stator interaction. Direct, as well as turbulence-model calculations, provide insight into the mechanics of the unsteady flow and demonstrate the potential for controlling its effects. The results show that the interaction between the wakes and the stator blades produces a characteristic pattern of vortical disturbances, which have been correlated to the pressure fluctuations. Within the stator passage, the wakes migrate toward the pressure surface where they evolve into counterrotating vortices. These vortices are the dominant source of disturbances over the pressure surface of the stator blade. Over the suction surface of the stator blade, the disturbances are due to the distortion and detachment of boundary layer fluid. They can be reduced by tailoring the blade loading or by applying nonuniform suction.