Abstract:

To improve the opening and sealing performance of compliant foil face gas seal (CFFGS) during dynamic operation and to reduce the requirement for foil installation accuracy, a novel super-elliptical hole floating seal dam compliant foil face gas seal (SHFSD-CFFGS) structure is proposed. Unlike traditional CFFGS, SHFSD-CFFGS features super-elliptical hole textures in both the foil and sealing dam areas, with additional compliant bump foil support at the bottom of the sealing dam to form a floating dam area. Based on gas lubrication and dynamic theory, an aeroelastic coupling dynamic model of SHFSD-CFFGS is established and solved using direct numerical simulation. The dynamic performances of SHFSD-CFFGS and non-textured CFFGS are compared and analyzed, revealing the mechanisms by which super-elliptical hole textures enhance the dynamic performance of the seal. Simultaneously, aiming to increase the dynamic average opening force and reduce the dynamic average leakage rate of the SHFSD-CFFGS, an optimization design is conducted for super-elliptical texture and mechanical structure parameters. The results show that the super-elliptical hole texture in the slope area and floating dam area of SHFSD-CFFGS foil can produce secondary dynamic pressure effect and upstream pumping effect, which is helpful to improve the seal opening and sealing performance. Under the working conditions of this paper, when the super-elliptical coefficient n₂ of the floating dam area is set to 1, the inclination angles ϕ₁ and ϕ₂ of the inner and outer holes are both between 20° and 40°, the texture depth T_d2 ranges from 4 μm to 6 μm, the slender ratio γ varies from 1.75 to 2.25, the compliance coefficient α₂ of the floating dam area ranges from 5×10^-5 to 1×10^-4, the static ring mass m_s is between 0.1 kg and 0.2 kg, the spring stiffness k_s ranges from 9×10⁷ N·m^-1 to 1×10⁸ N·m^-1 and the auxiliary sealing ring damping c_z ranges from 9×10³ N·s·m^-1 to 1×10⁴ N·s·m^-1, SHFSD-CFFGS demonstrates superior comprehensive dynamic performance. These findings provide a valuable reference for the optimized design of the dynamic performance of CFFGS.

Key words: foil end face, gas film seal, super-elliptical texture, dynamic performance, optimization design

摘要：

为提高弹性箔片端面气膜密封（CFFGS）在动态运行过程中的开启性和密封性并降低箔片安装精度要求，提出一种新型超椭圆织构浮动坝箔片端面气膜密封（SHFSD-CFFGS）结构。基于气体润滑和动力学理论，建立SHFSD-CFFGS气弹耦合动力学模型并采用直接数值模拟法求解，对比分析SHFSD-CFFGS与无织构CFFGS的动态性能表现，揭示超椭圆型孔织构对提升密封动态性能的作用机理，并以提高SHFSD-CFFGS动态平均开启力、减小动态平均泄漏率为目标，开展超椭圆织构结构参数和力学结构参数的优化设计。结果表明：SHFSD-CFFGS箔片斜坡区和浮动坝区的超椭圆型孔织构能产生二次动压效应和上游泵送效应，有助于密封开启性和密封性的提升；在本文工况条件下，当浮动坝区超椭圆系数n₂取1、内外侧型孔倾角ϕ₁和ϕ₂均取20°~40°、织构深度T_d2取4~6 μm、方向因子γ取1.75~2.25、浮动坝区柔度系数α₂取5×10^-5~1×10^-4、静环质量m_s取0.1~0.2 kg、弹簧刚度k_s取9×10⁷~1×10⁸ N·m^-1、辅助密封圈阻尼c_z取9×10³~1×10⁴ N·s·m^-1时，SHFSD-CFFGS具有较优的综合动态性能。

关键词: 箔片端面, 气膜密封, 超椭圆织构, 动态性能, 优化设计