滑移流影响螺旋槽干气密封性能的解析法

干气密封低速运转时,气膜很小,受微尺度效应滑移流的影响明显.为准确、有效地计算低速运转下干气密封的性能,以螺旋槽干气体密封为例,采用有效黏性系数方程对Muijderman螺旋槽窄槽理论气膜压力控制方程进行修正,并加以求解,获得不同滑移流模型对干气密封端面开启力、泄漏量、气膜刚度的影响规律.在不同转速、不同膜厚条件下与文献中的有限元法计算结果进行比较.结果表明,通过近似解析法获得开启力、泄漏量、气膜刚度与对照文献差别不大.相同转速下,气膜厚度在0.6~1.2 μm时,随着气膜厚度的增加,开启力和气膜刚度变小、泄漏量变大;相同膜厚下,开启力、泄漏量、气膜刚度均随转速的增大而增大.多种滑移流模型计算结果基本重合.

An approximately analytical method of characteristics of spiral groove dry gas seals under slip flow conditions

The film of dry gas seal is very thin at low speed, and the micro-scale effect slip flow has great influences on dry gas seals. In order to calculate the performances of dry gas seals at low speed, the spiral groove dry seals were taken as an example, and the effective viscosity coefficients equation was used to modify the pressure controlled equation from Muijderman′s spiral narrow groove theory. The modified equation was solved in order to find the influence law of different slip flow models to dry gas seals′ opening force, leakage rate and film stiffness. The result from above equation is compared with the result from the finite element method under different shaft speeds and film thicknesses. The comparison indicates that the results of opening force, leakage rate and film stiffness based on the approximately analytical method quite close to the results from the references. When the gas film thickness is 0.6-1.2 μm at the same shaft speed, the opening force and film stiffness decrease while increasing the film thickness. The opening force, leakage rate and film stiffness increase with the increasing shaft speed. The result of different slip flow models are basically in coincidence.