基于逾渗理论的超低温泛塞密封圈的性能分析

Performance Analysis of Ultra-low Temperature Variseal Based on Percolation Theory

泛塞密封圈能够补偿压缩量偏差,具有良好的高速表面动态性能,但由于泛塞密封圈壳体主要采用热膨胀系数较大的塑料,因此在液氢环境下常常会导致密封性能下降,甚至产生较大的泄漏。本文基于逾渗理论,考虑密封面粗糙度因素,建立超低温旋转泛塞密封圈热固耦合分析模型,以液氢环境下的摩擦力和泄漏量为密封性能的评价指标,分析了不同壳体材料对密封性能的影响程度,以外径、密封唇厚度、内径为主要参数,分析了各密封壳体结构参数对密封性能的影响程度,得到给定要求下的最优模型尺寸参数,并进行了试验验证。结果表明:在液氢环境5MPa介质压力下,相同结构参数的聚三氟氯乙烯(F3)壳体材料摩擦力是聚四氟乙烯(F4)的2.26倍,泄漏量为0.867倍。当其它结构不变时,泛塞密封圈外径越大,摩擦力增大而泄漏量减小;厚度越厚,密封圈摩擦力与泄漏量越大。泛塞密封圈经过结构参数优化后,在介质压力为5MPa时,泄漏量最大下降了63.30%。

The Variseal can compensate the compression deviation and has good high-speed surface dynamic performance.However,since the material of casing mainly uses plastics with large thermal expansion coefficients,it often leads to a decrease in sealing performance and even a large leakage in ultra-low temperature environments such as liquid hydrogen.Based on the percolation theory,considering the roughness of the sealing surface,this paper established the thermo-solid coupling analysis model of ultra-low temperature rotating variseal,analyzed the influence of different casing materials on the friction and leakage of variseal in ultra-low temperature environment.The friction and leakage in the liguid hydrogen environment are used as the evaluation indexes of the sealing performance.The outer diameter,the thickness of the sealing lip and the inner diameter are the main parameters.The influence of each casing structural parameter on the sealing performance is analyzed.The optimal model size parameters under the given requirements are obtained and verified by experiments.The results showed that under the medium pressure of 5MPa in liquid hydrogen environment,the friction force of polytrifluorochlor oethylene(F3)casing material with the same structural parameters is 2.26 times that of polytetrafluor oethylene(F4),and the leakage is 0.867 times.When other structures remain unchanged,the larger the outer diameter of the variseal,the larger the friction force and the smaller the leakage.The thicker the thickness of the variseal,the larger the friction and leakage of the variseal.After the optimization of the variseal structural parameters,the leakage rate decreased by 63.30%at the medium pressure of 5MPa.