低压涡轮叶栅流动分离主动控制实验研究

Experimental Investigation of Active Control of Flow Separation at Low-pressure Turbine Cascade

实验研究了低雷诺数条件下射流式旋涡发生器(VGJs)控制的低压涡轮叶栅,实验在西北工业大学吹气式低速涡轮平面叶栅风洞中进行,进口雷诺数范围为19000～260000,自由流湍流度为1%。实验中对VGJs吹气比为0～8,53%Cx,63%Cx和72%Cx射流位置,0°,30°,60°和90°射流偏斜角度,25000,50000和100000雷诺数状态下叶栅出口流场和表面静压进行了测量。研究发现,VGJs有效地控制了低雷诺数条件下叶栅吸力面的流动分离;VGJs需要一个最小有效吹气比,大于此吹气比时,VGJs效果基本上不变,高吹气比VGJs效果稍微减弱;VGJs射流偏斜角越大,控制效果越好,90°偏斜角效果最好;位置对VGJs效果影响很大,VGJs控制流动分离的最佳位置应该在分离点附近;随着雷诺数提高,VGJs效果减弱,更高的雷诺数,VGJs会增大叶片损失。

The experimental investigation was performed for votex generator jets （VGJs） controlling flow separation occurred in the suction side of low pressure turbine at low Reynolds number conditions. The experiments were conducted on the low-speed linear cascade tunnel at Northwestern Polytechnical University （NPU）. Cases at Reynolds numbers ranging from 19 000 to 260 000 were considered at the free-stream turbulence intensity about 1 %. The detail measurements of skin pressure coefficient at exit and blade were applied for blowing ratio from 0 to 8, for three injection locations of 53°, 63° and 72° Cx, for four skew angles from 0° to 90°, and three Reynolds number conditions of 25 000, 50 000 and 100 000. The results showed that the VGJs drastically reduce the suction surface boundary-layer separation at low Reynolds numbers. A minimum blowing ratio is required to reduce separation effectively. VGJs performance is essentially flat above this minimum blowing, with only a slight increase in losses at very high blowing ratios. The VGJs with skew angle of 90° are proven most effective to control the flow separation. The VGJs are proven to be the most effective when injecting around nominal separation point. At higher Reynolds numbers conditions, the VGJs become ineffective and make losses increasing.