端部效应修正螺旋窄槽理论应用于液膜机械密封的解析法

针对螺旋槽上游泵送机械密封的研究和设计过程中,利用未考虑修正因素的近似解析法所得结果与试验结果偏差进行比较,为准确、高效地解析计算螺旋槽上游泵送机械密封的性能,考虑液体进入螺旋槽时会产生压力损失的“端部效应”,对螺旋槽根处的压力进行了修正,获得了修正后的液膜压力分布近似解析表达式和密封的开启力.并将开启力与未修正的近似解析计算结果、数值模拟结果和试验结果进行了比较.结果表明:修正后的近似解析计算结果与数值模拟结果和试验结果基本吻合,当密封处于低压差工况时,与数值模拟结果的平均相对误差为19％,最大相对误差为62％,与试验结果的平均相对误差为86％,最大相对误差为155％;当密封处于高压差工况时,与数值模拟结果的平均相对误差为19％,最大相对误差为25％.研究结果可为上游泵送机械密封等液膜润滑机械密封的研究、设计和应用提供参考.

Analytical method for liquid film mechanical seals based on theory of narrow spiral groove with end effect modification

In the design of upstream pumping mechanical seal with spiral grooves, the end effect in which a pressure loss occurs at the inlet of spiral grooves when the liquid is pumped into the grooves is not taken into account, causing in a significant deviation in analytical prediction from experimental observation. In order to predict the performance of a mechanical seal accurately and efficiently by an analytical method, the end effect is considered, i.e. the pressure at the spiral groove root is modified in this paper. The modified analytical expressions of liquid film pressure and opening force are obtained. The opening force is compared with the force obtained by the analytical method without end effect or with experiment or based on numerical simulation. The opening force with end effect is consistent with the experimental measurement and the numerical prediction. Compared with the numerical simulation, the mean and maximum errors in opening force are 1.9% and 6.2%, respectively, under a low pressure difference condition; compared with experimental data, however, these error increase to 8.6% and 15.5%. The averaged and maximum errors in opening force are 1.9% and 2.5% compared with numerical simulation under a high pressure difference condition. The results can provide a reference for the investigation, design and application of upstream pumping mechanical seals.