计入空化效应的水润滑径向滑动轴承数值模拟研究

发布时间：2018-08-06 21:05

【摘要】：对水润滑进行理论与应用研究,可以为以水为润滑介质的各种摩擦副以及各种环保型机械的开发提供理论基础和参考依据,并可以解决机械设备因润滑油泄漏而造成的生态环境污染的问题、净化和保护人类赖以生存的环境,为建设可持续发展的资源节约型和环境友好型社会服务。水润滑轴承的摩擦学性能受轴承材料、结构、工况等影响很大。如何选择和设计水润滑轴承的材料、结构,并使之在各种工况下具有较低的摩擦因数,同时又有较高的承载能力,目前尚无满意的方法。与油润滑相比,水润滑轴承水膜厚度较薄,热弹流润滑数值计算不易收敛;而且水润滑轴承极易从层流状态进入湍流状态和产生空化现象。另外,水润滑轴承开设了多个导水槽,其流体力学模型的建立比较复杂,因此对其润滑机理的研究也还没有取得重要进展和突破。计入了水的空化效应,本文对水润滑径向轴承进行热弹流润滑分析和湍流状态的动力润滑分析,分析了水润滑径向轴承的润滑性能。本文的主要研究内容和结论如下: 使用Reynolds空化边界条件,构造热弹流润滑基本方程组,并使用多重网格算法对热弹流润滑基本方程组求解,分析载荷、转速、轴瓦材料的力学性能对水润滑轴承的润滑性能的影响。给出不同弹性模量、不同载荷和转速下的无量纲压力曲线、无量纲膜厚曲线、最高温升和温度分布图。结果表明:在满足载荷、转速、摩擦磨损性能等时,应选择弹性模量小的材料;在载荷很大时,应选择弹性模量大的材料;弹性模量很大的轴瓦材料,材料改性重点是增加其自润滑性能和热传导系数。基于FLUENT软件包,对湍流润滑状态下水润滑径向滑动轴承进行数值模拟研究,寻求适合水润滑径向滑动轴承的湍流模型及其壁面函数法和空化模型。对具有直导水槽的水润滑径向滑动轴承进行数值模拟,分析其流场和润滑性能。结果表明:湍流状态下,对水润滑轴承进行数值模拟时,使用增强壁面函数法的三种k ε湍流模型和Schnerr and Sauer空化模型或Zwart-Gerber-Belamri空化模型计算求解的压力场与试验结果最吻合。在处于全膜润滑状态时,水润滑轴承开了直导水槽后,承载力下降,摩擦系数升高;导水槽越多,摩擦力越大,承载力越小。导水槽中除了有一个接近导水槽尺寸的漩涡外,还有其它的较小的漩涡存在。轴颈在轴向对称面上的周向压力曲线存在一个主压力峰和数个很小的独立压力峰。水润滑轴承的空化主要发生在轴颈表面。
[Abstract]:The research on water lubrication theory and application can provide the theoretical basis and reference basis for the development of various friction pairs with water as the lubricating medium and various environment-friendly machinery. It can solve the problem of ecological environment pollution caused by oil leakage of machinery and equipment, purify and protect the environment on which human beings depend for survival, and serve for the construction of resource-saving and environment-friendly society for sustainable development. The tribological properties of water-lubricated bearings are greatly affected by bearing materials, structures and working conditions. There is no satisfactory method to select and design the material and structure of water lubricated bearing and make it have lower friction coefficient and higher bearing capacity under various working conditions. Compared with oil lubrication, water film thickness of water lubricated bearing is thinner, thermal elastohydrodynamic lubrication numerical calculation is not easy to converge, and water lubricated bearing is easy to enter turbulent state from laminar flow state and produce cavitation phenomenon. In addition, there are many guiding tanks for water lubricated bearings, and the establishment of hydrodynamic models is quite complex. Therefore, no important progress and breakthrough have been made in the study of the lubrication mechanism of water lubricating bearings. Considering the cavitation effect of water, the thermo-elastohydrodynamic lubrication analysis and the dynamic lubrication analysis of the water lubricated radial bearing are carried out in this paper, and the lubricating performance of the water lubricated radial bearing is analyzed. The main contents and conclusions of this paper are as follows: using Reynolds cavitation boundary condition, the basic equations of thermo-elastohydrodynamic lubrication are constructed, and the basic equations of thermo-elastohydrodynamic lubrication are solved by multi-grid algorithm. The influence of the mechanical properties of bearing materials on the lubricating properties of water lubricated bearings. The dimensionless pressure curve, dimensionless film thickness curve, maximum temperature rise and temperature distribution under different elastic modulus, different load and rotational speed are given. The results show that when the load, rotational speed, friction and wear properties are satisfied, the materials with small elastic modulus should be selected, the material with high elastic modulus should be selected when the load is large, the bearing material with high elastic modulus should be selected, and the bearing material with high elastic modulus should be selected. The emphasis of material modification is to increase its self-lubricating property and heat conduction coefficient. Based on FLUENT software package, the numerical simulation of water lubricated radial sliding bearing in turbulent lubrication state was carried out, and the turbulence model, wall function method and cavitation model for water lubricated radial sliding bearing were found out. The flow field and lubricating performance of water lubricated radial sliding bearings with straight guide flume were numerically simulated. The results show that the pressure field calculated by using three k 蔚 turbulence models, Schnerr and Sauer cavitation model or Zwart-Gerber-Belamri cavitation model is the best agreement with the experimental results when the water lubricated bearing is numerically simulated in turbulent state. In the state of full film lubrication, the bearing capacity of water lubricated bearing decreases and the friction coefficient increases after the water lubricating bearing opens the straight guide tank, and the more the guide tank, the greater the friction force and the smaller the bearing capacity. In addition to a vortex near the size of the guided-tank, there are other smaller swirls. There exists a main pressure peak and several small independent pressure peaks in the circumferential pressure curve of the journal on the axisymmetric plane. The cavitation of water-lubricated bearings mainly occurs on the surface of the journal.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH133.31

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