Numerical investigation on corner separation control in a linear compressor cascade by synthetic jet

Abstract

Corner separation is a kind of three-dimensional separation which occurs commonly in the junction of the endwall and blade corner region of high-loaded compressor. The increases of flow losses and the blockage associated with the corner separation have negative effect on the efficiency and stability of compressor. In this paper the flow control of corner separation by a synthetic jet is numerically investigated with the Reynolds Averaged Navier-Stokes/Large Eddy Simulation (RANS/LES) hybrid method to improve the cascade performance under the design condition. The synthetic jet is mounted on the blade suction side of a subsonic linear compressor cascade using NACA65 blade profiles. The influence of the synthetic jet on the vortex structures and unsteady characteristics in the cascade is investigated. The results indicate that, with the presence of synthetic jet, the passage vortex is weakened, and the corner vortex is receded indirectly. The intensity and range of the concentrated shedding vortex of the suction surface boundary layer are reduced. The total pressure loss coefficient is decreased by 25.8% at the design operating condition. Through calculating the entropy generation rate in the cascade, it is found that the blade profile loss is responsible for the additional flow losses. The synthetic jet significantly reduces the irreversible losses in the blade passage and wake region. From the perspective of the bimodal distributions of corner separation, the parameters increase first and then decrease, and the bimodal points appear in the abrupt velocity zone rather than at the separation points only.