涡轮叶栅流场的PIV测量实例

Example of PIV measurement technology on turbine

详细介绍了PIV的工作原理、数据处理流程和使用要点。针对涡轮内部复杂的流动特性,应用具有较高空间分辨率的非接触式瞬态速度的PIV测量技术,获得了较清晰完整的沿叶高平面和叶栅出口速度场的瞬时速度场信息,并据此分析了涡轮静叶出口二次流的流动特性。叶栅实验中将模拟动叶的圆柱列每次沿周向方向移动1/4节距,测量沿叶高平面的速度场。研究发现,前排圆柱尾迹进入叶栅流道不同,对叶栅内部流场气动效率影响巨大;同时由压力面向吸力面运动的二次涡(低能流体,耗能过程)逐渐向后传递、扩张,并在吸力面卷起、堆积,使吸力面附面层骤然增厚,并引起沿叶高总压损失系数和沿叶高出口气流角的剧烈变化。

PIV is a new measure instrument, which is better than others especially for complex flow field. The working rule, disposal flow chart and operation outline of PIV are introduced in detail. Finally, Example is carried out to measure the instantaneous entire velocity field along blade height and outlet plane with PIV. Secondary flow loss is the main part of turbine endwall loss, which is formed by flow tunnel turn, fluid viscosity and pressure gradient of adjacent eoneavoconvex stator side. Experiment measurement is adapted to secondary flow research. Cylinders with the same wake velocity and stagnant pressure loss replace upstream rotating blades, which move quarter of circumferential pitch each time to study the influence of upstream cylinder wake to downstream stator. The whole velocity field of horizontal plane and outlet plane has been measured with Particle Image Velocimetry （PIV）.