Influence of undissolved gas on the characteristics of high-speed water-lubricated bearings
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摘要: 水润滑轴承相比传统油润滑轴承,凭借其独特的优势,在各类高速精密旋转机械中均有重要应用.在实际工况中,润滑水中不可避免的混入一定量的难溶气体,参与整个润滑过程.运用计算流体力学CFD软件Fluent,基于气液两相流理论,对考虑湍流及气穴效应的高速水润滑轴承特性进行求解分析,研究难溶气体的含量对轴承间隙气相分布、压力峰值、轴承性能等特性的影响.结果表明:在高速水润滑轴承间隙中,气相基本分布于发散楔中,且最大气体体积分数存在于轴表面;在较小偏心情况下,一定量的难溶气体使轴承间隙内气相分布发生偏移,轴承承载力有所降低,但是对压力峰值和摩擦功耗并无明显影响;随着轴承偏心的增加,影响逐渐消失.Abstract: Unlike the traditional oil-lubricated bearing, the water-lubricated bearing has unique advantages because of which lead it has important applications in all types of high-speed rotating machinery. Under actual working conditions, the lubrication water will inevitably mix with a certain amount of undissolved gas, which too will participate in the lubrication process. In this study, computational fluid dynamics (CFD) software Fluent was used to analyze the characteristics of the high-speed water-lubricated bearing and to investigate the influence of the amount of undissolved gas on the phase distribution of the gas phase, pressure peak value, and bearing performance. The full cavitation model and gas-liquid mixture model were employed in this study. The results show that in the highspeed water-lubricated bearing clearance, the gas phase is distributed in the divergence wedge, and the maximum gas volume fraction exists on the surface of the shaft; When the eccentricity is small, a certain amount of undissolved gas can offset the gas phase distribution in the bearing gap and reduce the load-carrying capacity of the bearing. However, the gas appears to have no clear influence on the pressure peak and the frictional power consumption. As the bearing eccentricity increases, the influence of the undissolved gas disappears gradually.
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