Performance optimization of a transonic compressor using synthetic jets based on vortex breakdown suppression

Abstract

Tip leakage vortex breakdown, as a strong unsteady phenomenon, is recognized as an important inducing factor for compressor rotating stall. In this study, a validated numerical simulation was conducted to analyze the impact and control mechanism of synthetic jets on the performance of a transonic compressor from the perspective of tip leakage vortex breakdown suppression. The results indicate that the baseline compressor's stall mechanism is as follows: under near stall condition, an unsteady flow process dominated by the tip leakage vortex breakdown exists in the blade tip. During this process, the flow capacity diminishes, leading to an emergence of leading-edge spillage, which subsequently triggers rotating stall. Synthetic jets yield considerable improvement in the compressor performance. In cases synthetic jets positioned at 25%, Cax achieves a maximum improvement of 10.97% in the stability margin, while synthetic jets placed at 50% Cax gives an improvement of peak efficiency by 0.82%. The mechanism for performance improvement is as follows: synthetic jets suppress the vortex breakdown, disrupt the inherent feedback mechanism in the tip flow field, and reduce the blockage within the passage, thereby achieving an extension of the stability margin. Specifically, during the injection phase, an induced vortex suppresses the breakdown of the tip leakage vortex, thereby reducing the blade loading. In the suction phase, the tip leakage flow is reduced, which weakens the recirculation zone and causes the interface between the mainstream and the leakage flow to shift downstream. This research provides technical support for the development and optimization of efficient, wide-margin compressors.