螺旋槽结构参数对干气密封动态特性的影响研究

基于气体润滑理论,并通过小扰动法建立了螺旋槽干气密封微扰膜压控制方程,在高速高压条件下分析了螺旋槽结构参数对气膜动态特性系数的影响规律;基于动力学相关知识,在考虑动环轴向振动和角向偏摆的情况下建立了挠性安装静环运动方程,分析了膜厚的扰动行为,同时在考虑轴向和角向气膜扰动的共同作用下,提出以端面膜厚最大扰动量峰值和扰动稳定时间作为表征密封动态追随性的参数,并以此作为目标函数对螺旋槽结构参数进行优化.结果表明:在不同的高压条件下,当槽台宽比κ取0.9~1.5,槽坝比δ取1.8~2.4,螺旋角φ取18~24°,槽深h_g取6~8μm时,螺旋槽干气密封具有较好的动态追随性;在动态特性系数中主动态刚度对密封动态追随性的影响最大.

The Influence of Structure Parameters of Spiral Groove on Dynamic Characteristics of Dry Gas Seal

The perturbation film pressure governing equations of spiral groove dry gas seal (S-DGS) were presented by perturbation method based on gas lubrication theories,and the influence of structure parameters of spiral groove on dynamic force coefficients were analyzed in the condition of high-speed and high-pressure.The motion equations of flexibly mounted stator for analyzing the gas film thickness disturbance were presented when the rotor runout and misalignment were taken into consideration.With the combination of axial and angular gas film disturbance,the peak of film thickness disturbance on whole seal face and the disturbance stability time as objective functions for optimizing the structure parameters of spiral groove was put forward to represent dynamic tracking property of DGS.The results show that,at the different high-pressure conditions,excellent dynamic tracking property could be obtained for the S-DGS when the groove-to-land ratio was between 0.9 and 1.5,the groove-to-dam ratio was between 1.8 and 2.4,the spiral angle was between 15° and 24°,the groove depth was between 6 μm and 8 μm.The main dynamic stiffness coefficients had a more important influence on dynamic tracking property compared with other dynamic force coefficients.