计入热作用的微造型轴承及脂润滑轴承摩擦学性能研究

发布时间：2018-11-27 12:28

【摘要】：滑动轴承常出现由润滑失效引起的烧瓦和润滑剂汽化引起的腐蚀,这会严重影响机械系统的稳定性和安全性。上述失效现象是由温度过高引起的,而现有文献大多忽略了轴承系统温度的影响。因此,计入温度作用下研究滑动轴承的摩擦学性能,对减少滑动轴承摩擦磨损、减弱气化腐蚀和提高承载性能具有重要意义。本文立足于国家自然科学基金项目“仿生硅藻典型壳壁结构的水润滑轴承摩擦学性能研究”(项目编号51375509),分别探讨计入热作用下微造型对水润滑轴承的润滑性能、气穴现象影响,以及脂润滑轴承的润滑机理。论文主要工作如下:论文首先建立了具有半圆微沟槽表面造型的滑动轴承数学模型,应用ANSYS14.5中的CFX模块和静力分析模块对其进行流固热耦合分析,研究计入热作用下微造型对滑动轴承的润滑性能影响。研究表明:考虑热作用后,润滑剂温度升高,粘度减小,轴承承载力和摩擦力降低。轴颈转速越大和轴承偏心率越高,热作用越明显。表面微造型的优化布置位置是高压区和靠近高压区的压力下降区。接着,将半圆微沟槽表面造型分布在靠近轴承高压区的压力下降区,通过求解雷诺方程和Rayleigh-Plesset方程,首先研究微造型对水润滑轴承气穴现象中单气泡动力学的影响,在此基础上研究了微造型对水润滑轴承多气泡动力学的影响。研究表明:溶解于水中的气泡随着压力不断震荡,在低压区气泡半径急剧增大。适当增大微造型宽度,减小微造型深度和间距可以减小气穴现象中气泡最大半径,从而降低气泡破裂时产生的瞬时高压和高温,最终减弱轴承的气蚀现象。最后,建立了Herschel-Bulkley润滑脂多维热弹性润滑模型,由此研究光滑和粗糙表面轴承脂润滑的润滑机理。数值结果表明:随着流变系数的增大,润滑油膜压力增大,温度升高,同时轴承承载力、摩擦力和摩擦功耗增大。热作用使得润滑膜压力减小,进一步导致轴承的承载力、摩擦力和摩擦功耗减小。
[Abstract]:Sliding bearing often occurs corrosion caused by lubrication failure and vaporization of lubricant, which will seriously affect the stability and safety of mechanical system. The above failure phenomenon is caused by excessive temperature, but the influence of bearing system temperature is largely ignored in existing literatures. Therefore, it is of great significance to study the tribological properties of sliding bearings under the action of temperature in order to reduce friction and wear of sliding bearings, weaken gasification corrosion and improve bearing capacity. Based on the National Natural Science Foundation project "study on tribological properties of water lubricated bearings with typical shell wall structure of bionic diatoms" (item No. 51375509), the lubricating performance of water lubricated bearings with micro-moulding under heat action is discussed respectively in this paper. Effect of cavitation phenomenon and lubrication mechanism of grease lubricated bearing. The main work of this paper is as follows: firstly, the mathematical model of sliding bearing with semicircular groove surface modeling is established, and the fluid-solid-heat coupling analysis is carried out by using CFX module and static analysis module in ANSYS14.5. The effect of micro-modeling on lubrication performance of sliding bearing was studied. The results show that the temperature of lubricant increases, the viscosity decreases, and the bearing capacity and friction force decrease. The higher the journal speed and the higher the bearing eccentricity, the more obvious the thermal action. The optimal position of surface micro-modeling is high-pressure region and pressure-descending area near high-pressure area. Then, the surface modeling of semicircular micro-grooves is distributed in the pressure drop area near the high pressure region of the bearing. By solving Reynolds equation and Rayleigh-Plesset equation, the effect of micro-modeling on the single bubble dynamics in the cavitation phenomenon of water-lubricated bearing is studied. On this basis, the effect of micro-modeling on multi-bubble dynamics of water-lubricated bearing was studied. The results show that the bubble radius increases sharply in the low pressure region. By increasing the width of micro molding properly and decreasing the depth and spacing of micro molding, the maximum radius of bubble in cavitation phenomenon can be reduced, thus the instantaneous high pressure and high temperature produced by bubble rupture can be reduced, and the cavitation phenomenon of bearing will eventually be weakened. Finally, the multi-dimensional thermoelastic lubrication model of Herschel-Bulkley grease was established, and the lubrication mechanism of smooth and rough surface bearing grease was studied. The numerical results show that the pressure and temperature of lubricating oil film increase with the increase of rheological coefficient, and the bearing capacity, friction force and friction power consumption increase. Thermal action reduces the lubrication film pressure and further reduces bearing capacity, friction force and friction power consumption.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TH133.3;TH117.1

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