轴流压气机转子近叶尖流动的试验和数值研究之一:准定常工况流动特征分析

Experimental and Numerical Investigation of Near-Tip Flow-Field in an Axial Flow Compressor Rotor-Part I:Flow Characteristics at Quasi-Steady Operating Conditions

采用机匣壁动态压力测量技术对某高速亚音轴流压气机转子中转数可压条件下不同工况点叶尖流场进行了测量。在对试验测量结果进行详细分析的基础上,结合全通道定常数值模拟结果对试验观察到的流动现象进行了解释。结果表明:随着工况点从大流量向近失速工况推进,主流和间隙流交接面位置向叶片前缘平面推进,这是试验测量态压力FFT分析中的整个带宽范围的高幅值区向叶片前缘平面移动的原因。当工况点推进到近失速边界的某一点时,位于叶片通道中的动态压力传感器感受信号的FFT分析中均发现了低于叶片通过频率的一定带宽的高幅值区,这表明近叶尖流场出现了类似于"旋转不稳定性"的非定常流动现象。

Instantaneous casing static pressure measurements were conducted to explore the flow characteristic at different stable operating conditions for a small-scale axial flow compressor rotor at 54% design speed compressible flow condition. Fast Fourier transformation （FFT） of instantaneous pressure for 4 quasi-steady operating conditions （gkl through gk4） showed a high amplitude region over broad band moved toward leading edge plane as the flow rate decreased, which was due to the forward movement of interface between tip clearance flow and incoming flow according to the current whole-passage steady simulation results. At the measured near stall operating point of gk4, an excitation band lower than blade passing frequency （BPF） appeared on FFT analysis of instantaneous pressure signals acquired by probes within tip passage. This indicated that an unsteady phenomenon similar to rotating instability （RI） occurred in near-tip flow field of the test rotor.