似叠罗汉槽干气密封的结构优选与性能研究

针对现有干气密封在高速条件下所存在的泄漏率大、气膜刚度不足等问题,在干气密封螺旋槽结构的基础上,基于叠加组合思想提出一种似叠罗汉槽端面密封结构.基于气体润滑理论,建立了似叠罗汉槽端面的几何模型和数学模型,采用有限差分法求解二维稳态雷诺方程,获得了密封端面压力分布.以气膜刚度最大作为优化目标,对比分析了不同结构型式的优选叠加组合槽干气密封与普通螺旋槽干气密封的密封性能参数,数值分析了周向槽宽比、径向槽宽比和槽深比等结构参数对似叠罗汉槽干气密封性能的影响规律,获得了似叠罗汉槽主要结构参数的优选值范围.结果表明:在高速低压条件下,相较于普通螺旋槽干气密封,似叠罗汉槽干气密封在泄漏率基本不变的同时能显著提升气膜刚度,综合密封性能显著提升,且转速越高,压力越小,这种性能优势越明显.

Geometric Optimization and Seal Performance of a Pyramid-Like-Groove Dry Gas Seal

With regard to the problems of a dry gas seal (DGS) under high speed conditions, e.g. large leakage rate and insufficient gas film stiffness, a new type of Pyramid-like groove dry gas seal (PL-DGS) was introduced on the basis of spiral groove DGS structure and the superimposed combined conception. Geometric and mathematical model of PL-DGS were set up according to the theory of gas lubrication. A two-dimensional steady Reynolds equation was solved to obtain pressure distribution at end face by using the finite difference method (FDM). Taking the maximal gas film stiffness as optimization objectives, comparative analysis of sealing performance between different structural types of optimal superimposed combined grooves and common spiral groove dry gas seal was conducted. Numerical simulations were carried out to analyze the influence of groove depth and groove width in circumferential, radial direction on sealing performance, and the optimization of the main geometric parameters of PL-DGS was also demonstrated. The results show that this new type of DGS could keep the leakage rate almost unchanged and significantly improve gas film stiffness. Comprehensive sealing performance was much better compared to common spiral groove dry gas seal at high speed and low pressure. Moreover, the higher the speed, the lower the pressure. Hence the performance advantages were more obvious.