高速低温动静结合型机械密封结构优化及运转试验

在分析高速涡轮泵轴端非接触动静结合型机械密封所处的高速、低温、高压力、低黏度介质润滑等极端工况基础上，发展了考虑密封副固体、被密封流体、弹性补偿支撑单元等在内的热、流、固、力耦合的密封综合性能求解模型。基于此模型，完成了对处在低温、低黏度润滑介质下的机械密封运转性能的分析及关键结构参数的优化，优化的目标为密封承受载荷力W和泄漏量Q为最大及液膜产生的功耗（或温升）较小。以优化后的密封样件开展了低温液氮模拟介质运转试验，考察优化后密封在低温条件下的快速启动特性和摩擦特性。结果表明:低温高速工况下的密封外人字槽和内螺旋槽组合结构的槽数为30、槽深为3μm为一类优化结果，低温运转试验表明正常工作时端面摩擦因数为0.14。 

Optimization and test of parameters of the cryogenic hydrodynamic mechanical seal

Based on analyzing the extreme working conditions, such as high-speed, cryogenic, high-pressure and low viscosity lubricants, a thermo-elastic-hydrodynamic-mechanical multi-field coupling model for the non-contact hydrodynamic mechanical seal in the high-speed turbopump was presented, and the model couple the multi-parts in the seal system, such as seal stator, rotor, sealed fluid and the static supporting elements. The performances of the seal are obtained by solving numerically the coupling model and the main parameters of the seal are optimized. The optimization targets are the maximum of the open force of the seal W and the leakage Q and the minimum of the seal-film generated power (or temperature rise). The seal sample with the optimization parameters is used in the experimental test with the liquid nitrogen as the sealed fluid, and the rapid start-up and friction characteristics of the seal under the cryogenic conditions are obtained. The results show the optimization parameters of the seal with the internal spiral-shaped and external herringbone grooves combination structure are that the groove number is 30 and the groove-depth is 3μm. The friction coefficient of the seal under the cryogenic conditions is 0.14.