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. Sweeping jet actuators (SJAs), in particular, have steadily been used in turbomachinery to reduce loss due to their wide sweeping range. However, most of the preliminary studies were focused mainly on computational fluid dynamics 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. Comparing SJAs and hole-Type steady jet actuators (HSJAs), the influence on the tip leakage flow and the loss characteristics at various 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. The loss at the cascade outlet drops by up to 10.3% when the jet flow of an SJA equals 0.2% of the inlet flow, which is significantly better than that with an HSJA (6.3%).