汽轮机叶顶间隙变化对叶顶泄漏流动的影响

Tip Clearance Impact on Tip Leakage Flow in Steam Turbine

采用k-ωsst湍流模型,应用SIMPLEC算法对汽轮机叶顶间隙内的泄漏流动进行数值模拟,并详细分析了3种间隙条件下叶顶间隙区域内蒸汽的流动特性。结果表明:泄漏流动在叶片吸力面处形成顺时针的泄漏涡,其涡量的数值为正值,方向指向叶片的尾缘;上通道涡为逆时针,涡量的数值为负值,方向指向叶片的前缘。间隙泄漏流阻碍了主流的流动,随着间隙高度的增加主流速度大幅度下降,这说明随着间隙高度的增加,泄漏流动对主流的干涉作用越强,使主流流动特性的改变越大。

Through k-ω sst turbulence model and making use of SIMPLEC algorithm,the leakage flow within blade tip clearance of steam turbine was simulated and the steam flow characteristics in the blade tip clearance were analyzed under the condition of three blade tip clearances.The results show that the leakage flow on the blade suction surface can produce a clockwise leakage vortex toward the blade trailing edge,and the vortex value is positive; while the vortex in upper channel is anti-clockwise toward the front edge of the blade,the vortex value is negative.The tip leakage flow obstructs the flow of main stream,and it drops sharply with the increase of the tip clearance height.It illustrates that with the increase of tip clearance height,the main flow interferes with the tip leakage flow greatly,and this incurs a bigger modification.This investigation provides the guidance for the control of leakage flow in the turbine blade tip clearance and the reduction of leakage loss.