空腔倾向对泄漏影响的流动分析

FLOW ANALYSE INFLUENCE OF CAVITY INCLINATION ON LABYRINTH LEAKAGE

关键词:  迷宫密封体  数值计算  流动稳定性

Key words:  Labyrinth seal  Numerical calculation  Flow instability.

摘要:

给出了前倾斜腔、矩形空腔和后倾斜腔三种结构的四空腔迷宫密封实验结果。通过数值求解非定常Ｎ－Ｓ方程，预测了上述三种结构的单空腔迷宫通道的内部流动。计算结果表明：后倾斜腔结构内部是稳态流动，而对于前倾斜腔和矩形空腔结构，流动表现为总体结构的基本稳定和局部结构的不稳定，局部不稳定的强弱顺序依次是前倾斜腔、矩形空腔和后倾斜腔的迷宫结构。通过分析局部结构不稳定对减小泄漏的作用机制，说明不稳定效应的强弱是造成密封效果优劣的重要原因之一。

Abstract:

Firstly, seal test results of four-cavity labyrinthes are presented for forward-inclined, rectangular and backward-inclined cavityes. Secondly, the unsteady N-S equations are solved to predict the single-cavity labyrinth internal flow for three cases mentioned above. The numerical results reveal that, for forward-inclined and rectangular cases, the flows are in dynamic equilibrium which means between the essential stability of general structure and the instability of particular structure, while the flow is steady for the backward-inclined case. In sequence of instability from high to low they are forward-inclined, rectangular and backwardinclined cavityies. The effect of instability of particular structure on leakage decrease is discussed. It is indicted that the difference in instability intensity is the main cause of the difference in seal efficiency among the three types of cavityies.