轴流压气机转子叶尖二次涡的试验验证及形成机理

Experimental Validation and Formation Mechanism Analysis of Tip Secondary Vortex in a Compressor Rotor

关键词:  轴流压气机  叶尖二次涡  动态压力测量  小波分析  间隙流  泄漏涡

Key words:  Axial compressor  Tip secondary vortex  Dynamic pressure measurement  Wavelet method  Tip clearance flow  Leakage vortex

摘要:

对轴流压气机转子机匣壁面静压进行动态测量,采用小波分析方法处理近失速工况动态压力测量信号,功率谱显示在与二次涡相近的频率上存在较高的能量带,能量峰值沿轴向的衰减与二次涡的变化规律相符,表明二次涡在流场中存在是可能的。针对相同转子进行全通道非定常数值模拟,计算结果表明,近失速工况下,转子圆周每个通道叶顶附近均存在规律一致的二次涡运动。叶片中后段间隙泄漏流与间隙泄漏涡破碎产生的低能流体相互作用,在泄漏涡破碎形成的堵塞区域中形成二次涡。二次涡运动使得近叶顶载荷分布发生变化,从而导致近叶顶流场出现了一种周期性的自维持的非定常流动现象。 

Abstract:

Pressure variation on a compressor rotor casing wall was detected dynamically and wavelet method was used to analysis the dynamic static pressure signals detected on the rotor casing wall. The results show that there is a high-energy band near the tip secondary vortex frequency on the power spectrum map and the attenuation of the peak value along axial direction is consistent with the motion of tip secondary vortex. It indicates that the tip secondary vortex may exist in real flow field. Full-annulus unsteady simulation was conducted on the same rotor. According to the analysis of the full-annulus computation results, at near stall condition, there are accordant secondary vortexes in all the passages near the blade tip. Tip leakage flow from aft part of the tip gap interacts with the low-energy fluid caused by the breakdown of leakage vortex, which forms a tip secondary vortex in the blocking area. The tip secondary vortex affects the distribution of blade-loading near the blade tip which induces a cyclically self-excited flow phenomenon in the tip flow field.