高低齿迷宫气封在汽轮机级中应用的数值研究

为了研究迷宫汽封应用于实际结构的汽轮机中的流动特性及密封机理,采用商业软件CFX数值模拟了带有平衡孔和迷宫密封结构的某汽轮机高压一级半汽轮机内部流动。以第八级静叶隔板汽封为例,详细分析了所采用的高低齿迷宫气封的流动特性及密封机理。结果表明:在静叶隔板中应用转子带台阶的高低齿迷宫气封,与直通型迷宫气封相比,使泄漏气流发生多次折转,产生数量众多的大涡拟序结构与杂乱无章的小涡旋,强化了泄漏气流的动能耗散,从而明显增加了静叶隔板的密封性能。优化匹配迷宫气封的转子台阶、长短齿与大小间隙,能够进一步提高迷宫气封的气动性能。

Numerical Study on the Application of Stepped Labyrinth Seal in Turbine Stage

In order to study the flow characteristics and sealing mechanism of the labyrinth seal used in turbine with actual structure, numerical simulation on the three-dimensional flow field of one and a half turbine stage with balance holes and the labyrinth seal structure was carried out by using the commercial software CFX, and the detailed analysis of the flow characteristics and sealing mechanism of the static diaphragm stepped labyrinth seal was carried out. The results shows that: compared with straight-through labyrinth seal, in the stator diaphragm, rotor with stepped teeth labyrinth seal can make the leakage flow occur turning repeatedly, produce numerous large eddy coherent structure and disorder small vortex, and strengthen kinetic energy dissipation of the leakage flow, which can increase sealing performance of the stator diaphragm obviously. Optimization matching of rotor steps, high and short teeth and the size of gap of labyrinth seals, which can further improve the aerodynamic performance of labyrinth seal.