基于圆弧斜缝处理机匣的压气机叶顶泄漏流实验和数值研究

Experimental and Numerical Study of Compressor Tip Leakage Flow Based on Arc-Curve Skewed Slot Casing Treatment

为研究处理机匣对压气机总体性能、叶顶流动非定常性以及旋转不稳定性的影响,基于圆弧斜缝处理机匣对一台单级低速轴流压气机叶顶泄漏流进行被动控制.通过实验对不同工况下的叶顶脉动压力进行频谱分析,并对比机匣处理前后压气机性能以及转子叶顶区域流场特性的变化.结果表明:圆弧斜缝处理机匣能够使压气机获得6.8%的失速裕度提升量,抑制旋转不稳定性现象对应的频谱上的宽频带凸起,推迟泄漏涡的起始位置,进而消除了跨越相邻叶片周向传播的流动现象.斜缝内形成的回流能够抽吸低速流体,减少流道堵塞,改善叶顶的通流能力.

To explore the influence of casing treatment on compressor overall performance, flow unsteadiness, and rotating instability(RI) at blade tip region, arc-curve skewed slot casing treatment is applied to the passive control of the tip clearance flow of a single-stage low-speed axial compressor. The spectrum analysis of blade tip fluctuating pressure under different operating conditions is conducted, and the changes of performance and flow field characteristics at rotor tip region before and after casing treatment are compared. The results show that arc-curve skewed slot casing treatment could increase stall margin by 6.8%, suppress the broadband hump in the frequency spectrum caused by RI, delay the starting position of the leakage vortex, and eliminate the circumferential flow propagation across adjacent blades. The backflow formed in the skewed slot can suck low-velocity fluid, reduce the blockage in the flow passage, and improve the flow capacity near blade tip.