Passive self-excited sweeping jet control of compressor cascade separation for high-efficiency thermal systems

Improving compressor aerodynamic efficiency is important for advanced thermal and power systems, where flow separation and off-design operation can lead to considerable aerodynamic losses. In this study, a passive self-excited sweeping jet actuator (SSJA) was numerically investigated for laminar separation control in a controlled-diffusion airfoil compressor cascade. The GEKO turbulence model, validated against experimental total pressure loss contours and suction-surface oil-flow patterns, was used to analyze the effects of SSJA outlet sweeping angle and incoming Mach number. Seven outlet sweeping angles, θ _jet = 30°, 50°, 70°, 80°, 90°, 100°, and 110°, were compared while maintaining the same actuator geometry and installation position. The results show that the control effectiveness varies non-monotonically with θ _jet. The optimal performance occurs at θ _jet = 90°, where the total pressure loss is reduced by 17.89%, the static pressure rise is increased by 15.81%, and the outlet deviation angle is reduced by approximately 2°. Flow-field analysis indicates that θ _jet = 90° promotes a transition from localized pointwise actuation to broader surface coverage, achieving a favorable balance between jet intensity and suction-surface coverage and effectively weakening the trailing-edge spanwise vortex. Under variable Mach number conditions, the SSJA shows increased sweeping frequency and momentum output while maintaining effective separation control, indicating good passive adaptability for variable-condition compressor operation.