轴流通风机叶顶区域流动的实验研究

将粒子图像测速(PIV)技术应用到低速轴流通风机实验台上，在设计工况下对轴流通风机转子叶顶区域的瞬态速度场进行了实验测量，对3个不同叶顶间隙高度，分别测量得到了在3个不同周向平面上的速度．同粒子多普勒测速仪(PDA)时均测量结果进行比较，认为PIV可以得到与PDA相近的测量精度．根据PIV实验测量结果，重点研究了叶顶泄漏流动的涡旋结构，叶顶泄漏涡位置的不稳定性和锁相平均后的叶顶泄漏涡涡心的轨迹，并将实验结果与原有模型进行了比较．结果表明，叶顶泄漏涡涡心的运行轨迹与原有模型得出的估算公式的计算结果接近。

Experimental Study on the Tip Leakage Flow of an Axial Fan

The flow field in the tip region of an axial ventilation fan was investigated with a PIV(Particle Image Velocimeter) system at the design condition. Characteristics of a ventilation fan are an extreme low-pressure difference and a large tip clearance with a low rotating speed. Flow fields with three different tip clearances are surveyed on three different circumferential planes, respectively. The phase-locked average method is used to investigate the generation and the development of a tip leakage vortex. The result from PIV system was compared with that from a PDA(Particle Dynamics Anemometer) system. Both data are in good agreement. The structure of the tip leakage vortex for the rotor was illustrated. The characteristic of a leakage vortex was described in both velocity vectors and vortical contours. It is found that the tip leakage flow for low speed and a low pressure ventilation fan also has a chance to roll up into a discrete vortex at three different tip clearances, which is similar to high speed and high-pressure compressors and turbines. When the tip clearance increases, the scope and the location variation for the tip leakage vortex increases. Finally, the trajectory of the tip leakage vortex by the experimental measurement is compared with predictions from the existing models for high speed and high-pressure compressors and turbines. A good agreement is obtained.