带间隙轴流转子顶部三维整体平均速度测量

用三维激光多普勒测速系统对带间隙轴流转子顶部流场进行测量.在15个不同轴向位置上,获得在90%叶高以外的转子内部、进口以及出口三维整体平均速度分布.根据所测量得到的三维速度,清楚地展现了转子顶部流动的特性,特别是泄漏流对顶部流动的影响.泄漏流沿叶顶弦线从顶部流出,在叶片吸力面侧形成泄漏涡,叶片的旋转运动使得泄漏涡核心向压力面靠近.在顶部区域泄漏流和主流发生混合作用,并被认为是叶顶泄漏流动所造成的主要流动损失之一.

Ensemble-average three-dimensional velocity measurement in the tip region of axial rotor with tip clearance

The flow field in the tip region of axial rotor with tip clearance is measured with three-dimensional PDA system. The measurement is taken at the 15 different axial locations upstream, inside and at the exit of the rotor, mainly focusing on the outer 90% blade span. From the plot of three-dimensional velocity, the tip leakage flow can be clearly (investigated.) The tip leakage flow originating along the chord is penetrated into the flow passage. The tip leakage flow have chance to roll up into a discrete vortex at the suction side of the blade. The leakage vortex is moved more near to the pressure side due to the relative motion between the casing wall and blade. The form and development of leakage flow vortex could be seen from the secondary flow vector at different axial locations. The mixing action between the leakage flow and the main flow is though as one of main loss sources.