轮轨论文高速轮轨黏着特性数值分析

1、轮轨论文：高速轮轨黏着特性数值分析【中文摘要】”十一五”期间我国高速铁路的发展取得了辉煌的成就。随着列车运行速度的不断提高,轮轨间的低黏着问题越发明显。由低黏着引起的轮轨表面擦伤、剥离、扁疤等损伤时有发生。轮轨黏着是关系高速铁路行车安全和正常运营的关键问题。因此,开展高速轮轨黏着特性的研究具有重要的工程应用价值和理论指导意义。本文首先基于全膜弹性流体动力润滑理论,考虑轮轨实际接触载荷和尺寸,研究轮轨表面光滑时,计算分析了轮轨间存在“第三介质”油和水时的轮轨接触状态,获得了全膜润滑下的轮轨接触压力和膜厚分布,得到了实际膜厚大小的数量级。然后,基于部分膜弹性流体动力润滑理论和Patir-Cheng

2、的平均流量模型,建立了高速轮轨黏着特性数值分析模型,计算分析了在考虑轮轨表面粗糙度情况下的高速轮轨黏着特性。由于数值稳定性问题,对于油润滑情况下的计算采用Newton-Raphson方法,对于粘度较低的水时采用稳定性比较好的多重网格法。利用数值模型,研究了列车运行速度、轮轨表面粗糙度、轴重和轮径等对轮轨黏着特性的影响规律。对比了水润滑和油润滑下黏着系数随速度的变化情况,从膜厚比的角度解释了水润滑下的黏着系数比油润滑下的黏着系数低的原因。由于轮轨黏着理论和数值分析的困难性,以上数值模型假设为二维线接触模型。通过数值计算,可以得出以下结论：(1)由全膜润滑弹流计算获得的实际膜厚的量级可以看出膜厚和

3、粗糙度基本处于同一等级,所以轮轨间的接触处于部分膜润滑的过程。轮轨黏着问题研究应考虑部分膜的情况。(2)通过部分膜弹流润滑计算获得了水和油润滑下的压力和膜厚分布。发现油和水润滑时的压力分布与Hertz接触压力不一样,油润滑时存在二次峰,水润滑没有二次峰,固体接触压力和膜厚基本成倒影关系。(3)油和水润滑情况下,速度对黏着系数的影响都是一样。随着速度的增大,黏着系数均会降低。相同条件下,水润滑下的黏着系数要比油润滑下的大得多,这和试验结果相似。这是由于水膜厚度比油膜厚度小得多,产生的粗糙峰压力要比油大得多。(4)油和水润滑情况下,随着粗糙峰高度的增大,黏着系数均增大。轮轨表面纹理方向对黏着系数影

4、响较大,横向纹理的中心膜厚要比纵向纹理的大,而横向纹理的黏着系数要比纵向纹理的小。(5)油和水润滑情况下,随着轴重的增大,黏着系数逐渐降低；随着轮径的增大,黏着系数逐渐增大。【英文摘要】During the Eleventh Five-Year Plan, the development of high speed railways of China has been a great success. With an increasing train speed, low adhesion between rail and wheel becomes more and more apparen

5、t. Surface damages on wheel-treads such as flats, skidding marks and shelling occur due to low adhesion. The study of the adhesion between the wheel and rail becomes one of the key technologies of improving the riding quality and safety. Thus the study of the adhesion between the wheel and rail is o

6、f significant theoretical and practical importance.The thesis first simulates a water or oil lubricated wheel/rail contact based on the full elastohydrodynamic lubrication (EHL) theory considering the real load between the rail and wheel and the real rail/wheel radius. The distributions of the liqui

7、d pressure and the film thickness are obtained using the EHL theory under the state of oil or water lubrication. The magnitude of the film thickness is determined. Second, partial elastohydrodynamic lubrication theory with Patir-Chengs average flow model is used to model the characteristics of the a

8、dhesion between rail and wheel of the high speed rail vehicles taking surface roughness into consideration. To maintain the stability of the numerical calculation, Newton-Raphson method is used in the state of oil contamination. As the viscosity of water is low, multigrid method is used to study the

9、 state of water lubricated condition. The relationships between the speed, roughness, contact pressure, wheel radius and the adhesion of rail/wheel have been studied using the developed numerical model. In the end, comparisons are made for the adhesion coefficient under water and oil lubricated cond

10、itions at different speeds. The results explained the decrease of the adhesion coefficient. A simplified two dimensional line contact model is used to model the contact between the wheel and rail due to the difficuties of the adhesion theory and the numerical analysis.Several conclusions can be made

11、 according to the numerical simulation in this study:(1) The results of full lubrication show that the film thickness and the surface roughness are on the same level. The actual contact between wheel and rail is partial lubrication. Partial lubrication theory must be employed in the investigation of

12、 this problem.(2) The distributions of liquid pressure and pressure carried by solid and film thickness are obtained by partial EHL calculation. The distribution of pressure is different from Hertzian contact pressure. There is a spike near the outlet region under oil lubrication, which doesnt appea

13、r under water lubrication. Under oil lubrication the pressure carried by solid and film thickness like reflection relation. (3) The effects of speed on the adhesion under water and oil lubricated conditions are alike. With an increasing train speed, the adhesion between wheel and rail decreases. The

14、 decrease of the adhesion coefficient under water lubrication is greater than that under oil lubricated condition, which is the same as trend observed in the experimental test. Because the film thickness of water is larger than that of oil, the load carried by solid under water lubrication is much l

15、arger than that under oil lubrication.(4) With an increase surface roughness, the adhesion between wheel and rail increases under oil and water lubrication. The parameter of roughness orientation affects the adhesion coefficient. Under oil lubricated condition, when the roughness is transversly orie

16、nted, the nominal central film thickness is higher than the central film thickness when the roughness is longitudinally oriented. The adhesion coefficient shows a reversed relationship with respect to the roughness orientation.(5) With an increasing contact pressure, the adhesion between rail and wh

17、eel decreases gradually under water or oil lubrication. With an increasing wheel radius, the adhesion between rail and wheel increases gradually.【关键词】轮轨 黏着 速度 弹性流体动力润滑 多重网格 Newton-Raphson【英文关键词】wheel/rail adhesion speed partial elastohydrodynamic lubrication multigrid method Newton-Raphson method【目录

18、】高速轮轨黏着特性数值分析摘要6-7Abstract7-8第1章 绪论11-191.1 研究背景及意义11-121.2 国内外研究现状12-171.3 论文研究思路及主要工作17-19第2章 等温弹性流体动力润滑理论19-332.1 弹流理论的基本假设及基本方程19-232.1.1 基本假设192.1.2 弹流基本方程19-232.2 弹流问题的基本解法23-272.2.1 入口区分析解23-242.2.2 完全数值解24-272.3 部分膜弹流润滑基本方程的数值求解27-322.3.1 参数的无量纲处理272.3.2 方程的离散27-302.3.3 多重网格法的缺陷方程30-312.3.4 算例31-322.4 本章小结32-33第3章 水、油润滑下的弹流计算33-393.1 计算模型333.2 计算参数33-343.3 水油计算结果对比34-353.4 计算参数对全膜弹流特性的影响35-383.4.1 速