Aerodynamic Performance and Leakage Flow in Turbine Cascades with Sweeping Jet Actuators


 In recent years, unsteady flow-control technology has been considered as more promising for reducing secondary flow loss in turbines. In particular, because of their large sweeping range, sweeping jet actuators (SJAs) have gradually been applied to turbomachinery to reduce loss. However, most of the preliminary studies were focused mainly on computational fluid dynamics (CFD) calculations, with very few on wind-tunnel experiments to verify the flow-control effectiveness. To fill this gap, an innovative attempt to investigate experimentally the influences of SJAs on the aerodynamic performance and leakage flow is presented in a high-pressure turbine cascade. By comparing SJAs and hole-style steady jet actuators (HSJAs), the influence on the tip leakage flow and the loss characteristics with different incidences and injection frequencies are discussed in detail. The results indicate that the SJAs effectively reduce the magnitude and extension of the leakage vortex and the passage vortex, and weaken the interactions between them. When the jet flow of an SJA is 0.2% of the inlet flow, the loss at the cascade outlet decreases by up to 10.3%, which is significantly better than that with an HSJA (6.3%).