计算流体润滑频变动力学特性的一种完整变量扰动偏导数法

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振动与冲击 ›› 2022, Vol. 41 ›› Issue (20) : 68-77.

论文

毕春晓1,2，韩东江1,2，杨金福1,2

作者信息 +

A partial derivative method for frequency dependent dynamic coefficients embracing complete variables perturbation

BI Chunxiao1,2，HAN Dongjiang1,2，YANG Jinfu1,2

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文章历史 +

摘要

高速旋转机械使用工质流体润滑轴承既能彻底避免工质被油污染，又降低密封技术难度同时简化轴系结构以提高轴系动力学性能。然而特种参数下流体有着复杂的热物性，从而带来润滑膜的湍流、真实气体可压缩流动等多种附加效应。该研究从一般形式的可压缩湍流润滑雷诺方程出发，通过建立动态映射关系给出一种不局限于特定润滑流体或热物性模型的轴承静动特性分析通用方法，即完整变量扰动的偏导数法。该方法适用于具有附加效应的轴承与密封的频变动力学特性计算，能够统一处理结构扰动和润滑膜可压缩性带来动力学系数的频率效应。结合有限增量法，验证了完整变量扰动方法的准确性，并给出该方法应用于超临界二氧化碳、油润滑高速可倾瓦轴承动力学系数求解的案例。结果表明，忽略压力和膜厚以外的扰动变量将导致动力学系数明显偏大，该算例中刚度和阻尼系数的最大偏差分别为88%和93%。
关键词：润滑介质；真实气体效应；扰动频率；完整变量扰动；湍流润滑

Abstract

The process fluid lubricated bearings can avoid oil pollution completely and simplify the seals and rotor dynamics of high-speed rotating machineries. However, fluid with special parameters has complicated thermodynamic properties, which brings many additional effects, such as turbulence, real gas compressible flow and so on. Based on compressible turbulent lubrication Reynolds equation, a partial derivative method embracing complete variable perturbation was presented by establishing dynamic mapping, which is a general method for static and dynamic characteristics and is independent of lubricating fluid and thermodynamic model. The frequency effect of dynamic coefficients caused by both structural perturbation and compressible lubrication can be involved together by this method, which is suitable for calculating frequency dependent dynamic characteristics of bearings and dry gas seals with additional effect. Compared to the finite increment method, the accuracy of the complete variables perturbation method is verified. A method presented in this research was used in supercritical carbon dioxide and oil lubricated tilting pad bearings as example. The results show that neglecting the additional perturbed variables besides pressure and film thickness will overestimate dynamic coefficients. The maximum deviations of stiffness and damping coefficients in the examples of this paper are 88% and 93% respectively.
Key words: lubricant; real gas effect; perturbation frequency; complete variable perturbation; turbulent lubrication

导出引用

毕春晓1,2，韩东江1,2，杨金福1,2. 计算流体润滑频变动力学特性的一种完整变量扰动偏导数法[J]. 振动与冲击, 2022, 41(20): 68-77

BI Chunxiao1,2，HAN Dongjiang1,2，YANG Jinfu1,2. A partial derivative method for frequency dependent dynamic coefficients embracing complete variables perturbation[J]. Journal of Vibration and Shock, 2022, 41(20): 68-77

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