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环形微槽浮动密封的动态特性分析
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国家自然科学基金项目(51905480);宁波“科技创新2025”重大专项(2018B10006);宁波市自然科学基金项目(2019A610161)


Analysis of Dynamic Characteristics of Annular Microgroove Floating Seal
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    摘要:

    基于高参数旋转装备对密封低泄漏和长稳定的苛刻要求,提出一种环形微槽浮动密封;考虑偏心气膜收敛问题,定义了Rayleigh台阶对气膜周期的突变性,并应用小扰动法建立瞬态Reynold方程,获得压力和膜厚的扰动微量关系式;构建动态刚度与动态阻尼矩阵,并研究槽型结构与工况对动态特性系数的影响。研究结果表明:交叉刚度kxy和kyx的曲线与交叉阻尼cxy和cyx的曲线分别呈现对称性,主刚度kxx和kyy、主阻尼cxx和cyy的变化规律保持一致;在-20°与30°螺旋角下主刚度达到了最大值;在槽数为10时主刚度、主阻尼达到了最大值,同时交叉刚度之差与交叉阻尼之和趋于0,说明槽数为10时利于密封稳定;在转速超过38 000 r/min后密封系统有可能发生不稳定;压差对密封压力流和剪切流有明显的影响,使得密封系统处于涡动发散阶段;在大偏心下,楔形效应的增强抵抗了气膜压力与厚度分布的不均匀性,有利于涡动收敛,然而气膜厚度的增大增加了密封不稳定性的概率,从而推断出环形微槽浮动密封更适应于小膜厚、低压、高速、大偏心的服役工况。

    Abstract:

    Due to the harsh requirements of low leakage and long stability under high operating conditions,an annular microgroove floating seal was proposed.Aimed at the problem of dynamic characteristic,the convergence problem of eccentric gas film was considered,the mutagenicity of Rayleigh step to gas film period was defined,the transient Reynold equation was established by using small disturbance method,and the disturbance trace relation between pressure and film thickness was obtained.The matrixes of the dynamic stiffness and dynamic damping were constructed,and the effects of groove,structure and operating conditions on the dynamic characteristic coefficient were studied.The results show that the curves of cross stiffness kxy and kyx are symmetrical to those of cross damping cxy and cyx respectively,and the variation rules of main stiffness kxx and kyy,main damping cxx and cyy are consistent.The main stiffness reaches the maximum at the helix angle of -20°and 30°.The main stiffness and main damping reach the maximum when the groove number is 10,and the difference of the cross stiffness and the sum of the cross damping tends to zero,indicating that it is beneficial to the sealing stability when the groove number is 10.The sealing system may be unstable when the rotating speed exceeds 38 000 r/min.The pressure difference has an obvious influence on the pressure flow and shear flow of the seal,which makes the sealing system in the stage of vortex divergence.In the condition of large eccentricity,the enhancement of the cuneiform effect resists the nonuniformity of gas film pressure and thicknessdistribution,which is beneficial to the convergence of vortex.However,the increase of gas film thickness increases the probability of seal instability.It is inferred that the ring microgroove floating seal is more suitable for the service conditions of small film thickness,low pressure,high speed and large eccentricity.

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引用本文

陆俊杰,张 炜,谢方民,焦永峰.环形微槽浮动密封的动态特性分析[J].润滑与密封,2020,45(12):42-51.
LU Junjie, ZHANG Wei, XIE Fangmin, JIAO Yongfeng. Analysis of Dynamic Characteristics of Annular Microgroove Floating Seal[J]. Lubrication Engineering,2020,45(12):42-51.

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  • 在线发布日期: 2021-04-22
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