叶片弯曲对叶顶间隙流动影响的实验研究

 详细测量了直叶栅与正、反弯叶栅叶顶间隙中分面以及叶栅前、后横截面内气动参数分布，并对壁面（包括上、下端壁与叶片表面）流场进行了墨迹显示。对比３ 套叶栅的实验结果发现：叶片正弯削弱了泄漏流与端壁流道内横向二次流，泄漏涡与上通道涡合并，二次涡分离由整体分离转变为局部分离，既减少了相对漏气量又降低了掺混损失；叶片反弯加强了泄漏涡与上通道涡的相互作用，虽然使相对漏气量减少，但却增大了掺混损失。

EXPERIMENTAL STUDY OF THE EFFECT OF BLADE CURVING ON TIP LEAKAGE FLOW

Detailed measurements were carried out upstream, downstream and in the middle plane of tip clearance in three types of cascades: conventional straight blade cascade, positively curved blade cascade and negatively curved blade cascade. Flow visualization was also carried out on the blade surface and endwall surface. By comparison with the conventional straight blade cascade, the experimental results show that : (a) In positively curved blade cascade, leakage flow and crossflow near the endwall were decreased, up passage vortex disappeared, and secondary vortex separation type changed from closed separation to an open one; as a result, leakage flow through tip clearance and mixing losses downstream were decreased. (b)In positively curved blade cascade, leakage flow through tip clearance was also cut down, but mixing losses downstream were increased because of the strengthened interaction among leakage vortex, up passage vortex and secondary vortex.