輪軌論文高速輪軌黏著特性數(shù)值分析

1、輪軌論文：高速輪軌黏著特性數(shù)值分析【中文摘要】”十一五”期間我國高速鐵路的發(fā)展取得了輝煌的成就。隨著列車運行速度的不斷提高,輪軌間的低黏著問題越發(fā)明顯。由低黏著引起的輪軌表面擦傷、剝離、扁疤等損傷時有發(fā)生。輪軌黏著是關(guān)系高速鐵路行車安全和正常運營的關(guān)鍵問題。因此,開展高速輪軌黏著特性的研究具有重要的工程應(yīng)用價值和理論指導(dǎo)意義。本文首先基于全膜彈性流體動力潤滑理論,考慮輪軌實際接觸載荷和尺寸,研究輪軌表面光滑時,計算分析了輪軌間存在“第三介質(zhì)”油和水時的輪軌接觸狀態(tài),獲得了全膜潤滑下的輪軌接觸壓力和膜厚分布,得到了實際膜厚大小的數(shù)量級。然后,基于部分膜彈性流體動力潤滑理論和Patir-Cheng

2、的平均流量模型,建立了高速輪軌黏著特性數(shù)值分析模型,計算分析了在考慮輪軌表面粗糙度情況下的高速輪軌黏著特性。由于數(shù)值穩(wěn)定性問題,對于油潤滑情況下的計算采用Newton-Raphson方法,對于粘度較低的水時采用穩(wěn)定性比較好的多重網(wǎng)格法。利用數(shù)值模型,研究了列車運行速度、輪軌表面粗糙度、軸重和輪徑等對輪軌黏著特性的影響規(guī)律。對比了水潤滑和油潤滑下黏著系數(shù)隨速度的變化情況,從膜厚比的角度解釋了水潤滑下的黏著系數(shù)比油潤滑下的黏著系數(shù)低的原因。由于輪軌黏著理論和數(shù)值分析的困難性,以上數(shù)值模型假設(shè)為二維線接觸模型。通過數(shù)值計算,可以得出以下結(jié)論：(1)由全膜潤滑彈流計算獲得的實際膜厚的量級可以看出膜厚和

3、粗糙度基本處于同一等級,所以輪軌間的接觸處于部分膜潤滑的過程。輪軌黏著問題研究應(yīng)考慮部分膜的情況。(2)通過部分膜彈流潤滑計算獲得了水和油潤滑下的壓力和膜厚分布。發(fā)現(xiàn)油和水潤滑時的壓力分布與Hertz接觸壓力不一樣,油潤滑時存在二次峰,水潤滑沒有二次峰,固體接觸壓力和膜厚基本成倒影關(guān)系。(3)油和水潤滑情況下,速度對黏著系數(shù)的影響都是一樣。隨著速度的增大,黏著系數(shù)均會降低。相同條件下,水潤滑下的黏著系數(shù)要比油潤滑下的大得多,這和試驗結(jié)果相似。這是由于水膜厚度比油膜厚度小得多,產(chǎn)生的粗糙峰壓力要比油大得多。(4)油和水潤滑情況下,隨著粗糙峰高度的增大,黏著系數(shù)均增大。輪軌表面紋理方向?qū)︷ぶ禂?shù)影

4、響較大,橫向紋理的中心膜厚要比縱向紋理的大,而橫向紋理的黏著系數(shù)要比縱向紋理的小。(5)油和水潤滑情況下,隨著軸重的增大,黏著系數(shù)逐漸降低；隨著輪徑的增大,黏著系數(shù)逐漸增大?！居⑽恼緿uring 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.【關(guān)鍵詞】輪軌 黏著 速度 彈性流體動力潤滑 多重網(wǎng)格 Newton-Raphson【英文關(guān)鍵詞】wheel/rail adhesion speed partial elastohydrodynamic lubrication multigrid method Newton-Raphson method【目錄

18、】高速輪軌黏著特性數(shù)值分析摘要6-7Abstract7-8第1章 緒論11-191.1 研究背景及意義11-121.2 國內(nèi)外研究現(xiàn)狀12-171.3 論文研究思路及主要工作17-19第2章 等溫彈性流體動力潤滑理論19-332.1 彈流理論的基本假設(shè)及基本方程19-232.1.1 基本假設(shè)192.1.2 彈流基本方程19-232.2 彈流問題的基本解法23-272.2.1 入口區(qū)分析解23-242.2.2 完全數(shù)值解24-272.3 部分膜彈流潤滑基本方程的數(shù)值求解27-322.3.1 參數(shù)的無量綱處理272.3.2 方程的離散27-302.3.3 多重網(wǎng)格法的缺陷方程30-312.3.4 算例31-322.4 本章小結(jié)32-33第3章 水、油潤滑下的彈流計算33-393.1 計算模型333.2 計算參數(shù)33-343.3 水油計算結(jié)果對比34-353.4 計算參數(shù)對全膜彈流特性的影響35-383.4.1 速