雁型槽干式气体端面密封性能的数值分析

为了改善普通螺旋槽干式气体端面密封(S-DGS)的密封性能,引入了一种介于普通S-DGS和带环形槽S-DGS(即AS-DGS)两者之间的型槽轮廓类似飞行大雁的雁型槽DGS,即GS-DGS。基于气体润滑理论,建立了GS-DGS的数学分析模型,定义了GS-DGS的主要几何结构参数,采用有限元方法求解Reynolds方程,获得了端面气膜压力分布,分析了这些几何参数对端面开启力、泄漏率、气膜刚度、刚漏比等密封性能参数的影响规律,并根据确保GS-DGS具有较大轴向气膜刚度的同时泄漏率较低的原则,对几何参数进行了优化分析。结果表明,当槽台宽比δ=0.8～1.2,径向开槽宽度比φ=0.4～0.8,雁颈长比ε=0.25～0.35,雁颈宽比ζ=0.2～0.4,槽深比H=2.5～4.0,槽数N=10～18且螺旋角α=10°～18°时,GS-DGS具有最佳工作性能。

Numerical analysis of sealing performance of dry gas seal with goose-grooves

In order to improve the sealing performance of a dry gas seal with spiral grooves onto its faces(S-DGS), a new type of dry gas seal with its groove outline between S-DGS and a spiral groove dry gas seal with an annular groove(AS-DGS) was presented.The shape of surface grooves of such a new dry gas seal was similar to that of a flying goose, so it was simply named as GS-DGS.The geometrical parameters of flying goose grooves were defined.A two-dimensional Reynolds equation for controlling film pressure between the two faces of such a GS-DGS was set up according to the theory of gas lubrication.The finite element method was used to solve the Reynolds equation.The variation of opening force, leakage rate, axial film stiffness and ratio of film stiffness to leakage with the geometrical parameters of goose-grooves was studied.Optimization of such geometrical parameters was finished according to the principle of getting small leakage while maintaining high axial film stiffness.The results showed that excellent sealing performance could be obtained for a GS-DGS when the width ratio of groove and land was between 0.8 and 1.2, the radial width ratio of the groove was between 0.4 and 0.8, the goose neck groove length ratio was between 0.25 and 0.35, the goose neck groove width ratio was between 0.2 and 0.4, the groove depth to gas film thickness ratio was between 2.5 and 4.0, the number of grooves was between 10 and 18, and the spiral groove angle was between 10° and 18°.