Study on flow separation and suction control of a compressor tandem cascade

To control the boundary layer separation on the front blade suction surface in a compressor tandem cascade at a high incidence angle, three suction schemes at different axial positions were introduced and the cascade performance improvement and separation flow control effects were investigated. Based on the experimental and numerical simulations, the aerodynamic performance of the prototype tandem cascade reaches the peak at the incidence angle of 5°. Continue to increase the incidence angle, the loss increases sharply, and the static pressure rise coefficient and diffusion factor begin to decrease. With the boundary layer suction on the suction surface of the front blade, fluid energy in the upstream boundary layer of the suction slot is increased, and the adverse pressure gradient downstream is decreased. By suction, the development and separation of the boundary layer are inhibited, and the loss in the tandem cascade is significantly reduced. The flow control effect of the suction scheme at the onset location of boundary layer separation is the best, and the flow loss can be reduced by about 34.9% with a suction flow rate of 1% at the incidence angle of 5°. The suction schemes have good flow control effects in a wide working range and broaden the available range of incidence angles of the tandem cascade. This study provides a reference for the design of tandem blades considering flow control and has a positive significance for improving compressor efficiency and pressure ratio.