反转轴间双端面气膜密封性能分析

Seal performance analysis of double-faced gas film in counter-rotating intershafts

针对一种反转轴间双端面气膜密封系统的密封性能进行研究,建立系统二自由度力学平衡方程,通过有限元法求解双端面稳态气膜厚度以及气膜支反力;以瞬时扰动力与激振力模拟密封系统扰动,采用直接数值模拟法,求解密封系统的动态响应,使用快速傅里叶变换(FFT)处理振动信号。分析表明:动静压混合结构可在较大的膜厚范围内保持较高刚度,使系统密封特性提升兼有良好的稳定性。密封系统在瞬时力扰动下的收敛时间受密封跑道与主密封环质量比影响较大;在非共振频率的激振力下,密封系统动态稳定性良好;在共振频率的激振力下将会引起系统振动加剧、泄漏量增加,甚至失稳,设计中应予避免。

The performance of a double-faced gas film seal system used in counter-rotating intershafts was analyzed.The system ’s two-degree-of-freedom force balance equation was established.The thickness and force of the film were calculated with finite element method.The seal system’s dynamic response to seal disturbance simulated by instantaneous disturbing force and exciting force was solved with the direct numerical simulation.The vibration signal was processed by fast Fourier transform（FFT）.The results show that the hydrodynamic-hydrostatic hybrid structure maintains a higher stiffness in a wider thickness range and improves the seal system performance with a good stability.When disturbed by instantaneous force,the seal system’s convergence time is impacted by the mass ratio of track and sealing ring.When the exciting force’s frequency is not the natural frequency,the seal system is in good stability.Exciting force with resonance frequency strengthens the vibration,increases the leakage and even damages system stability.Thus,this situation should be avoided in the design.