基于微段组合的干气密封端面型槽结构模型及其参数影响

为解决现有干气密封端面型槽型线方程表征能力不强和结构参数定义体系不统一的问题，提出了一种基于径向微段组合以表征任意形状型线的广义对数螺旋槽结构模型。给出了广义对数螺旋槽结构参数定义体系，对比了不同压力和速度条件下广义螺旋槽与经典螺旋槽干气密封的开启力、气膜刚度和泄漏率等稳态性能，重点研究了广义螺旋角分布和型线周向偏转两个特征量对干气密封性能的影响，基于不同目标函数获得了广义螺旋槽的最优形状。结果表明：型槽上游侧壁型线形状对各项稳态性能参数均有显著影响，而下游侧壁型线形状仅对泄漏率和气膜刚度影响显著；经典对数螺旋槽是一种流体动静压效应很强的端面结构，单纯依靠型线优化难以使气膜承载力显著提高，不过在低压高速条件下优化广义螺旋角分布，在高压低速条件下合适设置型线周向偏转有望提高干气密封的气膜刚度和刚漏比。

Geometrical model of surface groove based on micro-segment combination for dry gas seal and its parameter influence

To solve the problem that the existing dry gas seal surface groove type line equations are not strong enough in geometrical characterization ability and not unified in the geometrical parameter definition, a generalized logarithmic spiral groove geometrical model based on the combination of radial micro-segments to represent arbitrary shape lines is proposed. The generalized logarithmic spiral groove geometrical parameter definition is given, and the steady-state performance of the generalized spiral groove and the typical spiral groove dry gas seal under different pressure and rotating speed conditions, such as the opening force, film stiffness, and leakage rate, are compared. The research focuses on the influence of the two characteristic features, including the generalized spiral angle distribution and the circumferential deflection of profile line, on the performance of the dry gas seal, and the optimal shape of the generalized spiral groove is obtained based on different objective functions. The results show that the profile shape of the upstream side wall of the groove has a significant impact on various steady-state performance parameters, while the profile shape of the downstream side wall only has a significant impact on the leakage rate and film stiffness. The typical logarithmic spiral groove is exactly a kind of surface groove with strong hydrodynamic and hydrostatic effect. It is difficult to significantly increase the load-carrying capacity of the gas film by relying solely on profile optimization of the surface groove. However, optimization of the generalized helix angle distribution under low-pressure and high-speed condition, and proper design of the profile circumferential deflection under high-pressure and low-speed condition are expected to improve the film stiffness and stiffness-leakage ratio of dry gas seals.