Abstract
The sweeping jet actuator (SJA), widely studied as a potential flow control method in compressors and turbines, results in unnecessary performance losses due to its requirement for additional energy and mass input. In this study, a self-excited sweeping jet actuator (SSJA) method was introduced to enhance the application feasibility of SJA. The SSJA was arranged inside the blade, utilizing the pressure difference between the pressure and suction surfaces; therefore, additional energy input is no longer necessary. Wind tunnel tests were conducted to explore the effects and mechanisms of SSJA layout, size, and pressure difference between the blade surfaces in controlling flow separation in a compressor cascade with controlled diffusion airfoils (CDAs). Transient pressure was measured to reveal the frequency characteristics of SSJA. Key aerodynamic parameters were measured using a five-hole pressure probe, and oil-flow visualization was also performed to represent flow characteristics. Results show that by using SSJA in the compressor cascade, a significant reduction of 27.04% of the total pressure loss coefficient at 2° incidence was obtained. This control effect has great potential for application in the field of passive flow control. The streamwise vortices (SV) induced by SSJA enhance the momentum exchange between the mainstream and the boundary layer near the suction surface, which suppresses the suction side boundary layer separation and thus greatly reduces the flow losses. In addition, due to the different flow separation characteristics and actuation conditions at different incidences, the SSJA flow control effect is sensitive to incidences.
