螺旋槽上游泵送机械密封摩擦系数的解析分析

上游泵送机械密封是一种具有环保、长寿命、低能耗的高新密封技术,其应用前景将十分广阔。端面液膜特性是决定上游泵送机械密封工作寿命和密封性能好坏的关键因素。主要依据流体雷诺方程和Muijderman无限窄槽理论,再用端面槽型因子对其进行修正,推导了螺旋槽上游泵送机械密封端面间液膜的径向压力分布、泄漏率、承载力、摩擦力、摩擦系数等液膜特性参数的计算公式,并重点分析了操作参数与槽型参数对端面摩擦系数的影响。研究表明,摩擦系数随转速和粘度增加而增加,随压力增加而减小。槽深H'=2.5、槽数Ng=10~18、槽宽比B=0.6~0.8、槽长比l=0.6~0.7时,密封环端面间摩擦系数较小,液膜特性较好,这时端面间间隙对摩擦系数几乎没有影响。此研究结果可为上游泵送机械密封的正确使用和设计提供依据。

Analytical Method of Friction Coefficient of Upstream Pumping Mechanical Seals with Spiral Grooves

Upstream pumping mechanical seals are a kind of high-new seal technology,the features of which is the environmental protection concept,long lifetime,low energy consumption,and its application foreground will be very broad. The friction state of the end faces of mechanical seals is a key factor that can decide their operating life and sealing performance. For upstream pumping mechanical seals with spiral grooves,the pressure distribution equations of the fluid film are derived from Reynolds equation of fluid and Muijderman infinite narrow Groove Theory. The equations for calculating the bearing force,the leakage rate and the frictional factor of the fluid film are also derived. The influence of Groove parameters and operational parameters on the friction coefficient was analyzed. The results indicate that the bigger the rotating speed and the viscosity of medium,the bigger the friction coefficient. And the bigger the medium pressure,the smaller the friction coefficient. When the depth of groove H' =2. 5,the number of groove Ng= 10 ~ 18,the width of groove B = 0. 6 ~ 0. 8,the length of groove l = 0. 6 ~ 0. 7,the friction coefficient is smaller and the characteristic of the fluid film is better. And the clearance of end faces has no significant influence on the friction coefficient. These results can be used in the application and the design of upstream pumping mechanical seals.