加载形式对涡轮叶尖泄漏损失的影响

Effects of Loading Distribution on Turbine Tip Leakage Losses

本文通过改变90%叶高截面叶型的安装角和厚度分布获得了不同的加载形式,并采用数值模拟方法对比分析了加载形式对叶尖泄漏流动和损失的影响。结果表明,叶尖加载形式影响了泄漏流的流量和法向/流向速度差沿轴向的分布,进而影响泄漏流动损失。随着叶尖负荷向前缘移动,叶尖泄漏总流量增大,当泄漏量和动量差沿轴向分布相对均匀,当地峰值减小,叶中附近所占比重增加;在泄漏量与动量差共同作用下,泄漏涡卷起位置向上游移动,但与主流掺混强度减弱,损失减小;采用均匀加载和前加载形式能有效降低泄漏流与主流的动量差,减小泄漏损失,提高涡轮性能。

Different loading forms are obtained by changing the stagger angle and thickness distribution of profile at 90% span,and the influence of loading form on tip leakage flow and loss is compared by numerical simulation method.The results show that the tip loading forms affect the flow of the leakage flow and the distribution of the normal/streamwise velocity difference along the axial direction,which affects the leakage flow loss.As the tip load moves toward the leading edge,the total leakage of the tip increases,the leakage and momentum difference are relatively uniform distribution along the axial direction,the local peak decreases,and the proportion near the middle increases.Under the joint action of the leakage and the momentum difference,position of the leakage vortex rolling moves upstream,but the mixing strength with the main stream is weakened,and the loss is reduced.The mid-load and front-load forms can effectively reduce the momentum difference between the leakage flow and the mainstream flow,reduce the leakage loss,and improve the turbine performance.