Abstract:

Cavitation occurrence in the liquid film affects the lubrication performance of mechanical seals. A mathematical model of spiral groove liquid film seal was established based on the mass-conserving JFO cavitation boundary condition. The Reynolds governing equation was solved by the streamline upwind finite element method, and cavitation distribution was obtained. The calculation result was verified by cavitation visualization experiment. The influence of spiral groove geometrical parameters on cavitation characteristics were analyzed with the critical speed and critical pressure of cavitation as the characterization. The results indicate that the cavitation area in spiral groove is of wing section type, and it increases with increasing rotating speed and decreases with increasing inner pressure. The maximum circumferential length of cavitation is located near the groove radius. The critical speed of cavitation increases with the increase of groove number and depth, but decreases with the increase of spiral angle, radial seal dam extent and groove width ratio. The changing trends of critical pressure of cavitation with geometrical parameters are opposite to those of critical speed of cavitations. The effective control of cavitation can be achieved by reasonable selection of geometrical parameters.

Key words: spiral groove liquid film seal, cavitation, geometrical parameters, critical speed of cavitation, critical pressure of cavitation, finite element method

摘要：

液膜中空化的产生会影响密封润滑性能。基于质量守恒的JFO空化边界条件，建立螺旋槽液膜密封数学模型，采用流线迎风有限元法求解Reynolds控制方程，获得端面空化分布，并通过可视化试验进行了验证。以空化临界转速和临界压力为表征，分析了螺旋槽结构参数对空化特性的影响。结果表明：螺旋槽内空化区域呈机翼截面型，且随着转速的增加而变大，随着内径压力的增加而减小，空化周向最大长度位于近槽根处；空化临界转速随着槽数、槽深的增加而增加，随着螺旋角、槽长坝长比、槽台宽比的增加而减小；空化临界压力随各结构参数的变化趋势与空化临界转速相反。通过对各结构参数的合理选择，可实现对空化的有效控制。

关键词: 螺旋槽液膜密封, 空化, 结构参数, 空化临界转速, 空化临界压力, 有限元法