Abstract
The rheological characteristics of the oil film on the rod-seal interface in the sealing zone have a major influence on the behavior of reciprocating seals. Because of the addition of polymers, the viscosity and temperature properties of hydraulic oil have improved and the fluid presents non-Newtonian characteristics. To investigate the influence of these characteristics on seal behavior, a soft elastohydrodynamic lubrication (EHL) numerical model is introduced to simulate a step seal under a mixed lubrication condition. A modified Reynolds equation is derived for calculating the fluid film pressure distribution more accurately. The equation is based on the power law fluid model and Jakobsson-Floberg-Olsson (JFO) cavitation theory. Results are presented to gain insight into the effect of non-Newtonian fluid characteristics on seal behavior, and the simulated results are compared to those of a Newtonian fluid to reveal the seal mechanism. The influence of operating parameters and the seal surface root mean square (RMS) roughness on sealing performance under different power law indexes is also investigated and discussed.
中文概要
目的
研究润滑油的非牛顿流体行为对液压往复活塞杆 的斯特封密封性能的影响,为密封设计提供理论 参考。
创新点
1. 基于幂律流体模型和JFO 空化理论,推导出同 时考虑粗糙度、流体空化和非牛顿流体效应的修 正雷诺方程;2. 建立非牛顿流体的混合润滑软弹 流模型,探究流体流变属性对斯特封密封行为及 性能的影响。
方法
1. 通过理论推导,建立混合润滑条件下非牛顿流 体的软弹流仿真模型;2. 对比分析不同工况条件 下假塑性(n<1)、膨胀型(n>1)两种典型非牛 顿流体和牛顿流体(n=1)对斯特封密封行为影 响的区别,揭示假塑性和膨胀型两种非牛顿流体 的密封机理。
结论
1. 非牛顿流体效应对液压往复斯特封密封性能具 有重要影响:幂律指数越大,流体的动压效应越 强,密封性能越好。2. 相比于牛顿流体,膨胀型 流体润滑条件较好,密封具有低摩擦低泄漏的优 点;假塑性流体润滑条件较差,密封摩擦力较大, 不易实现零泄漏。
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Project supported by the National Natural Science Foundation of China (Nos. 51575490 and 51775505), the National Basic Research Program (973 Program) of China (No. 2014CB046404), and the Zhejiang Provincial Natural Science Foundation of China (No. LZ15E050002)
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Wang, Bq., Peng, Xd. & Meng, Xk. Simulation of the effects of non-Newtonian fluid on the behavior of a step hydraulic rod seal based on a power law fluid model. J. Zhejiang Univ. Sci. A 19, 824–842 (2018). https://doi.org/10.1631/jzus.A1800096
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DOI: https://doi.org/10.1631/jzus.A1800096