Abstract: Dry gas seals with T-grooves onto its faces have been widely used in axial seal of a centrifugal compressor in petro-refinery and chemical process. The failures of such seals cannot be diagnosed correctly due to the lack of the theory of such seal geometric construction. In this paper, a finite element analysis was used to resolve Reynolds equation for the gas flow between the two faces of a non-contacting T-groove dry gas seal based on gas lubrication theory. The maximum value of gas film stiffness was selected as the optimization object for T-grooved face geometric parameters. The diversification law of opening force, leakage rate and gas film stiffness varied with geometric parameters of T-grooves in the different rotational speeds or sealed medium pressures was analyzed. The results showed that the rotational speed has great effect on the optimization values of T-groove geometric parameters, such as arc ratio α1, groove width ratio α2 and groove depth hg, but he effect of rotational speed on the optimization value of radial ratio β1 and groove length ratio β2 can be ignored. The higher the rotational speed, the greater the optimization values of α1 and hg, but the lower the optimization value of α2. The effect of the sealed medium pressure on the optimization values of α1, β1 and hg was great to a certain degree, but to the optimization values of α2 and β2, the effect could be ignored. The sensitivity of opening force, leakage rate and film stiffness to the above five geometric parameter values of T-groove would be lower when the sealed medium pressure was higher. The optimization values of α1 and hg would be lower when the sealed medium pressure became higher, but the optimization value of β1 would be higher. The results would provide the theoretical support for the practical utilization under the condition of different operational parameters of a T-groove dry gas seal.

Key words: operating conditions, dry gas seal, T-groove, seal performance, finite analysis method

摘要： T型槽干式气体端面密封（T-DGS）已被广泛应用于石化、化工用离心压缩机轴端密封中，但是目前缺少系统的设计理论与方法，因此也难以对T-DGS失效进行实质性分析研究。基于气体润滑理论模型，采用有限单元法求解控制密封端面间气体流动的雷诺方程，以最大气膜刚度为几何结构参数优选目标，分析了不同压力及转速条件下开启力、泄漏率和气膜刚度等密封性能参数随T型槽几何结构参数的变化规律。结果表明：转速对T型槽的型槽几何周向比α1、槽宽比α2和槽深hg优选值产生较大影响，对径向比β1和槽长比β2优选值的影响可以忽略不计；转速越高，密封性能参数达到最大值时所对应的α1和hg优选值越大，而所需要的α2优选值越小。密封压力对T-DGS的α1、β1及hg的优选值都将产生一定的影响，对α2和β2优选值的影响可以忽略不计；压力越高，密封性能参数对上述5个型槽几何结构参数的敏感度越小，且α1和hg的优选值越小，β1的优选值越大。研究结果为T-DGS在不同操作条件下的实际设计与应用提供了理论依据。

关键词: 操作参数, 干气密封, T型槽, 密封性能, 有限元法