迷宫汽封泄漏特性数值模拟

Numerical investigation on leakage characteristics of labyrinth seal

建立迷宫汽封三维数值分析模型,系统研究了压比、汽封间隙、齿尖宽度、台阶高度等参数对迷宫汽封泄漏特性的影响。结果表明:汽封泄漏量随压比的增加而增加,且增加率逐渐减小;无量纲参数"齿隙比"j(齿尖宽度与汽封间隙之比)可用于评价汽封内部流动特性的变化,当j≥1.0时,其变化对汽封内部流动特性的影响可以忽略,此时汽封泄漏量与汽封泄漏面积成正比,当j<1.0时,其变化会引起汽封内部流动特性的显著变化,此时在计算汽封泄漏量时应考虑齿隙比对流动特性的影响;台阶高度H_s变化对汽封泄漏量影响较小,但当H_s=0时,迷宫汽封退化为光轴结构,会引起泄漏量大幅增加43%以上,因此不建议在没有台阶的光滑轴面使用迷宫汽封。

The three dimensional numerical model for a typical labyrinth seal was built to investigate the influence of pressure ratio, seal clearance, tooth width and step height on leakage characteristics of the seal. The results show that, the seal leakage increases with the pressure ratio and the increase rate gradually decreases. The dimensionless parameter φ, which is defined as the ratio of tooth width to clearance, can be used to evaluate the flow characteristics in the labyrinth seal. When （o〉~ 1, the effect of φ on the flow characteristics in the labyrinth seal is negligible and the seal leakage is proportional to the leakage area. However, when φ 〈1, the variation of φ will cause the flow characteristics in the labyrinth seal change dramatically. It means that the effect of φ should be considered in the calculation of labyrinth seal leakage. When the step height Hs equals to 0, the labyrinth seal becomes a smooth configuration, which leads to an increase in the seal leakage by above 43%. Therefore, it is not advised to use the labyrinth seal when the axis face is smooth.