射流控制蜂窝叶顶间隙流动的数值研究

Numerical Study of the Leakage Control in a Turbine Cascade With Honeycomb Tip Using Injection

本文结合底面射流进一步强化蜂窝叶顶对高负荷涡轮平面叶栅间隙泄漏流动的控制,利用雷诺平均方法研究了间隙泄漏流动及气动损失。结果表明:蜂窝底面射流能强化蜂窝叶顶对间隙泄漏的控制效果,侧壁射流能实现最大降低间隙泄漏量约17.5%,同时下游能量损失下降约4.8%。三维流场分析表明:贴近叶顶的泄漏流体呈阶梯状进入蜂窝内部并卷起形成旋涡结构,抬起上方的泄漏流体穿过间隙;底面施加射流间接增大了蜂窝内部旋涡的展向高度,降低了泄漏流体的通流面积。

Control of the tip leakage is investigated in a turbine cascade with honeycomb tip using injection numerically. Tip leakage flow rate and energy loss coefficient are selected to evaluate the aerodynamic performance. Results show that the tip leakage flow rate and the energy loss downstream both can be further reduced after using the injection. Compared with the flat tip, tip leakage flow rate drops by up to 17.5 percent, and energy loss downstream is reduced by about 4.8 percent. From three-dimensional flow analysis, the leakage fluid enters the honeycomb cavities layer by layer along the span-wise direction and is involved into the internal vortices. The in.jection increases the span-wise scales of the internal vortices indirectly, raises the upper leakage fluid and reduces the leakage flow area.