动叶顶部泄漏流动特性及汽封结构优化研究

Study of Sealing and Flowing Performance at Rotor Tip and Optimization of Seal Structure

以某汽轮机低压段第一扭叶级为研究对象,对不同动叶顶部汽封结构的泄漏流动进行数值分析,绘制泄漏量与动叶效率随顶部间隙及压比的变化曲线。结果显示,在顶部间隙小于1 mm时,简化的迷宫汽封结构能够减少50%的泄漏量,动叶效率提高1.5%~2.5%。在迷宫汽封中添加周向阻流孔板,优化后的结构较迷宫汽封流量系数平均下降20%,对比显示,优化后汽封结构的流量系数对转速更加敏感。

With the first stage of twist blade in low pressure section in one turbine as investigated object,the numerical analysis for the flows with companioned leakage for different steam seal structures at the tip of blades were performed,and the curve for the relation of the leakage to the pressure ratio and the clearance at the tip of the blades was drawn.It was shown that when tip clearance is less than 1 mm,50%of the leakage in simplified labyrinth steam seal can be reduced,and the efficiency of the rotor blade be increased by 1.5%~2.5%.The flow coefficient of the labyrinth gas seal can be averagely decreased around 20%when being optimized with addition of circumferential choke orifice plate in labyrinth steam seal.However,in comparison,the flow coefficient for optimized gas seal will be more sensitive to rotation speed.