蜂窝衬套对篦齿封严静力与动力特性影响机理研究

Influence mechanism of honeycomb bushing on static and dynamic characteristics of labyrinth seal

关键词:  篦齿封严  蜂窝衬套  泄漏特性  动力特性  公式构造

Key words:  Labyrinth seal  Honeycomb bushing  Leakage characteristics  Dynamic characteristics  Formula structure

摘要:

蜂窝衬套对篦齿封严的泄漏特性和动力特性有较大的影响。本文建立蜂窝衬套篦齿封严数值求解模型，在验证数值方法有效准确的基础上，研究了蜂窝衬套篦齿封严泄漏量随进口压力、封严间隙及转速的变化规律，构造泄漏量理论公式；运用非定常动网格技术，建立多频椭圆涡动模型，分析了蜂窝衬套对篦齿封严泄漏特性和转子动力特性的影响机理。结果表明：蜂窝衬套篦齿封严泄漏量随进口压力、封严间隙的增加而增大，随转速的增加略有减小；在大间隙工况下（封严间隙大于0.5 mm），蜂窝衬套削弱气流的透气效应，减小泄漏量，对边距为0.8 mm蜂窝衬套篦齿封严的密封性能最佳。蜂窝衬套篦齿封严有着较大的直接阻尼和较小的交叉刚度，在高频涡动（频率大于120 Hz）时效果更明显；蜂窝衬套增大流场中的湍动能，增强气流能量的耗散速度，有利于提高封严性能；并且蜂窝衬套能够使周向压力分布更均匀，提高转子的稳定性。本文所构造的蜂窝衬套篦齿封严泄漏量理论公式，与数值仿真相对误差均在5%之内，能够准确地预测蜂窝衬套篦齿封严的泄漏量，满足工程实际需求。

Abstract:

Honeycomb bushing performs great influence on the leakage and dynamic characteristics of labyrinth seals. On the basis of verifying the effectiveness and accuracy of the numerical method， this paper studied the variation rules of honeycomb bushing labyrinth seal leakage with inlet pressure， sealing clearance and rotating speed， and established the theoretical formula of leakage by founding numerical model of honeycomb bushing labyrinth seal. A multi-frequency elliptic vortex model was established by using unsteady grid technology. The influence mechanism of honeycomb bushing on labyrinth seal leakage characteristics and rotor dynamic characteristics was analyzed. The results show that the leakage of honeycomb bushing seals increases with the increase of inlet pressure and seal clearance， and decreases slightly with the increase of rotating speed. In the case with large clearance （sealing clearance larger than 0.5 mm）， honeycomb bushing weakens the flow through effect and reduces the leakage， the sealing performance of the honeycomb bushing labyrinth seal with opposite edges distance of 0.8 mm is the best. Honeycomb bushing labyrinth seal has larger direct damping and smaller cross stiffness， and the effect is more obvious at high frequency vortex （frequency greater than 120 Hz）. The honeycomb bushing increases the turbulent kinetic energy in flow field and enhances the dissipation speed of the flow energy， which is beneficial to improving sealing performance. What’s more， honeycomb bushing can make the circumferential pressure distribution more uniform and improve the stability of the rotor. Compared with the numerical simulation， the relative error of the theoretical formula of honeycomb bushing labyrinth seals is within 5%， which can accurately predict the leakage of honeycomb bushing labyrinth seals and meet the actual engineering requirements.