Abstract:

Detailed flowfield measurements were made in the end-wall region of a four-stage low-speed large-scare axial compressor test rig. Two ten-hole survey boundary layer probes, one four-hole pneumatic probe, and several dynamic pressure probes each bedded with a high-frequency response Kulite sensor, were designed and manufactured to aid the test. Boundary layer region and mainflow region could be clearly distinguished from the boundary layer measurement results. A few parameters, including boundary layer thickness, displace thickness, momentum loss thickness, energy loss thickness and blockage coefficient were calculated based on the measurements. Results from turbulent boundary layer empirical formula of plate are in good agreement with the measurements, which indicates an excellent way of boundary layer effect estimation. Outlet flowfield of the third-stage rotor, measured by the displacement mechanism driven four-hole probe, shows that the lower end-wall boundary layer thickness is clearly smaller than that of the upper region, which can be contributed to the hub rotation. The evolution trajectory of TLV is identified evidently by dynamic pressure measurements. The maximum aerodynamic load point on the blade moves from the trailing to the leading edge as flowrate decreases, which leads to the forward movement of the tip leakage vortex inception point.

Key words: end-wall boundary layer, tip leakage vortex(TLV), rotating stall, compressor

摘要：

在四级低速大尺度轴流压气机试验台上，利用自行设计加工的十孔梳状附面层探针、四孔探针以及埋入高频响Kulite传感器的动态探针，针对端壁区流动展开了详细的流场测量。从附面层探针测量结果中能清晰识别出附面层区和主流区；获得了该压气机进口的附面层位移厚度、动量损失厚度、能量损失厚度及堵塞系数，且实验结果表明，采用平板紊流附面层公式能较好地进行附面层厚度的估算；采用位移机构带动四孔探针测得的第三级压气机转子进出口流场速度结果显示，受轮毂旋转作用，转子后的下端壁区附面层厚度明显要小于上端壁区附面层厚度；动态探针测量结果能较为明显地识别出叶尖泄漏涡的发展轨迹，且随着流量系数的减小，叶片尖部最大负荷点从尾缘向前缘移动，导致叶尖泄漏涡起始点前移。

关键词: 端壁附面层, 叶尖泄漏涡, 旋转失速, 压气机