Effects of combined sweeping jet actuator and winglet tip on aerodynamic performance in a turbine cascade

Compared with steady injection, the unsteady flow control techniques have received more attention in recent years and are considered to be more hopeful for reducing secondary flow losses in turbine stages. In particular, the sweeping jet actuator (SJA) is gradually being applied to reduce losses in turbomachinery due to its larger sweeping range. The objective of this study is to investigate the effect of combined flow control of SJA and the winglet tip structure on the aerodynamic performance and tip leakage flow of the turbine cascade through experimental and numerical methods. The effect of blade tip geometry on aerodynamic performance enhancement is discussed in detail by comparing flat and groove tips. The effect of injection flow on aerodynamic performance and secondary flow of turbine cascade with different blade tip structures is discussed by comparing SJA and hole-style steady jet actuator (HSJA). Compared with the flat tip without injection case, the combination of the winglet tip and SJA results in a maximum reduction of 20.1% in the total pressure loss at the cascade outlet, which is significantly better than the combination of the winglet tip and HSJA (16.2%). The results of the validated CFD calculations are also reported to help analyze the flow field and secondary flow loss mechanisms.