基于流线的拟合曲线槽干气密封流场的数值模拟及分析

Numerical simulation and analysis of flow field within flowline-based fitted curvilineal groove for dry gas sealing

推导两光滑平板间干气密封微尺度流动场的非线性雷诺方程,应用PH线性化方法、迭代法对非线性雷诺方程近似求解,得到气膜压力的近似解析式,利用极坐标下的流线方程,通过Maple程序求解压力方程和流线方程得到符合条件的拟合曲线.建立拟合曲线槽干气密封的三维立体模型,运用Fluent软件对拟合曲线槽干气密封在气膜厚度为3～5μm时3种工况下的压力和泄漏量进行数值模拟和分析,并与螺旋槽进行比较.研究结果表明:在低压低速下,拟合曲线槽和螺旋槽的动压效果都不明显,且泄漏量相差不大;在中压中速下,气膜厚度δ=3μm、δ=4μm时拟合曲线槽的动压效果比螺旋槽好,但两种槽的泄漏量相差不大;在高压高速下,气膜厚度δ=3μm时拟合曲线槽的动压效果比螺旋槽好,并且泄漏量比螺旋槽小.

Nonlinear Reynolds equation of microscale flow field within dry gas seal between two smooth plates was derived, and the approximate analytic gas film pressure was obtained by solving this nonlinear Reynolds equation with PH linearization method and iteration method. Flow line was obtained with Maple program for solving pressure equation and flow line equation in polar coordinate system. The flow-line in- deed was a fitted curve that met the conditions. Then a three-dimensional model of fitted curvilineal groove was established. Under three conditions, the numerical simulation and analysis of pressure and leakage of fitted curved groove for dry gas seal with gas film of 3 to 5 μm in thickness was conducted by using Fluent software, and the result was compared with that of spiral groove. The result showed that.dynamic pres- sure effect of fitted curve groove and spiral groove was not obvious and the difference in leakage between fitted curved groove and spiral groove was small under low pressure and speed condition. When gas film was 3 μm and 4 μm in thickness, the dynamic pressure effect of fitted curved groove was better than that of spiral groove and the difference in leakage between them was still small under pressure and speed condi- tion. When gas film was 3 μm in thickness, the dynamic pressure effect of fitted curve groove was better than that of spiral groove and the leakage of fitted curve groove was smaller than that of spiral groove un- der high pressure and speed condition.