高速輪軌黏著機理及特性的研究

吳兵 金學(xué)松 溫澤峰 王衡禹 趙鑫

摘 要：該研究建立了水油介質(zhì)污染條件下并考慮接觸表面粗糙度影響的三維高速輪軌黏著數(shù)值模型；建立了考慮彈塑性接觸和摩擦溫升情況下的二維高速輪軌黏著模型；初步建立了考慮流變、彈塑性變形及溫升的二維高速輪軌黏著模型。 在三維模型中，輪軌間的液體介質(zhì)可沿著橫向和縱向流動，且粗糙峰沿橫向和縱向分布的影響同時能得到考慮，與實際情況相符。考慮到三維模型的復(fù)雜性，在求解雷諾方程時采用多重網(wǎng)格法求解，利用多重網(wǎng)格積分法求解膜厚方程以加快求解速度。然后利用數(shù)值模型，以我國CRH2型高速列車的參數(shù)為基礎(chǔ)，對輪軌黏著進行了數(shù)值模擬計算，研究了輪軌間存在水、油污染時，列車運行速度及輪軌表面粗糙度等對輪軌黏著特性的影響規(guī)律。數(shù)值結(jié)果表明：（1）水介質(zhì)存在時列車運行速度增大會引起中心膜厚增大而引起黏著系數(shù)的急劇減小。（2）粗糙度增大引起膜厚比的減小，從而引起黏著系數(shù)的增大。縱向表面紋理有利于黏著特性的發(fā)揮。（3）將數(shù)值模型的部分結(jié)果與較低速度下的試驗結(jié)果進行了對比，吻合較好，驗證了數(shù)值模型在低速條件下的可靠性。 在建立考慮彈塑性接觸和摩擦溫升情況下的二維高速輪軌黏著模型時，基于H.Chen的簡化模型基礎(chǔ)上加入了入口區(qū)溫升、固體粗糙峰間的摩擦溫升以及考慮Zhao等提出的微觀粗糙峰間的彈塑性影響。對運行速度、接觸壓力等對黏著系數(shù)的影響進行了討論。主要得出以下幾個結(jié)論：（1）速度增大導(dǎo)致接觸區(qū)內(nèi)膜厚的增大，降低了固體承載比率，因而黏著系數(shù)下降。（2）接觸壓力越大導(dǎo)致固體部分接觸壓力增大，但是增大的量比總載荷增大的量小，固體峰承載的比率還是下降的，直接導(dǎo)致黏著系數(shù)的下降。速度相對于接觸壓力而言對黏著系數(shù)的影響更大。（3）彈性模型過高地估計了黏著系數(shù)，這對于保障列車行駛安全是不利的。（4）該模型考慮熱效應(yīng)的數(shù)值結(jié)果與日本新干線上的實測數(shù)據(jù)接近。該研究初步建立了一個同時考慮熱效應(yīng)（流體膜剪切及固體粗糙峰摩擦產(chǎn)生）、微觀粗糙度彈塑性變形及流體的流變效應(yīng)的高速輪軌黏著二維數(shù)值模型。采用多重網(wǎng)格法求解模型中的雷諾方程，以提高運算效率。整個求解流程采用壓力-溫度兩場交叉求解，直到求得收斂解。利用該模型得到合理的數(shù)值結(jié)果。

關(guān)鍵詞：高速鐵路 輪軌黏著 彈性流體動力學(xué)

Abstract：This project develops three numerical models to investigate wheel/rail adhesion of high-speed railway under water and oil contamination. The first one is a 3D numerical model considering surface roughness； The second one is a simple numerical model considering the elastic-plastic deformation of asperity contact and the flash temperature rise； The third one is a 2D numerical model comprising the rheology of liquid， the elastic-plastic deformation of asperities and the temperature across the film and solid.In the 3D model， the liquid could flow along the lateral and the longitudinal directions. The multilevel method is used to solve Reynolds equation， and in order to improve the efficiency， the multilevel multi-integration algorithm is applied to solve the film thickness equation. The results show that （1） The increasing train speed leads to the dramatically decrease of the adhesion coefficient.（2） The increasing roughness amplitudes leads to the increase of the adhesion coefficient. A longitudinally oriented roughness on the wheel/rail surfaces can increase the adhesion coefficient （3） The numerical solutions approximately coincide with the experimental results. An improved numerical model considering the elastic-plastic deformation of asperities，the viscous heating in the inlet zone and the flash temperature is developed under wet condition to estimate the wheel/rail adhesion of high-speed railway.The main conclusions are as follows：（1）The increase of train speed also causes the decreasing of the adhesion coefficient.（2）The asperity load always increases with contact pressure， but this increase is generally less than that in the contact pressure，which leads to the decreasing of the adhesion coefficient. The train speed has a bigger impact on the adhesion coefficient than the contact pressure.（3）The elastic model overestimates the adhesion coefficient.The present results are consistent with the experimental results.A primary 2D model considering temperature，the elastic-plastic deformation of asperities and the non-Newtonian property of liquids is developed to investigate the adhesion coefficient of high-speed railway.The numerical solution is achieved by a pressure–temperature iteration between the Reynolds equation and the energy equations until the two are convergence. The results obtained by the present model are reasonable.

Key Words：High-speed railway；Wheel-rail adhesion；Elastohydrodynamics

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