涡轮叶栅非定常流动的PIV实验

利用激光粒子图像测速仪(PIV)测量沿叶高平面和叶栅出口速度场的整场信息.实验中,将模拟动叶的圆柱列沿周向依次移动1/4节距,进行叶高平面速度场的测量,查看圆柱尾迹对下游叶栅影响的整场情况;同时研究在不同的相对叶高下,叶片顶部和根部的二次涡会合、脱离情况.研究发现:在较小的相对叶高下叶栅出口二次涡汇合,强度较大;而在较大的相对叶高下二次涡分离.同时,当上游圆柱的相对位置变化时,叶栅流动最高效率对应着圆柱尾迹被输运到下游静叶的前缘附近,最低效率对应着圆柱尾迹被输运到下游静叶的流道中央.

Experiment on turbine blade unsteady flow with PIV

Particle image velocimetry is used to measure the entire velocity field along blade height and outlet plane.In experiment,upstream cylinders move quarter of circumferential pitch position each time and the influence of upstream cylinder wake to downstream blade is studied.Tip and bottom secendary vortexes change under different relative blade height.It is found that outlet secondary flow is obvious and severe at small relative blade height.When the upstream rotor wake impinges upon the leading edge of the downstream stator,the corresponding stage efficiency will be higher;when the upstream wake is transferred into the mid passage of the downstream stator,the corresponding stage efficiency will be lower.At the same time,tip and bottom secondary vortexes change under different relative blade height.It is found that outlet secondary flow is obvious and severe at small relative blade height,when the upstream wake is transferred into the mid passage of the downstream stator,the corresponding stage efficiency will be lower.