Numerical investigation on the high‐speed wheel/rail adhesion under the starved interfacial contaminations with surface roughness

Abstract

This paper presents a new numerical model of wheel/rail in rolling contact to study the adhesion mechanism under the starved interfacial contaminations at high speed considering surface roughness. A thermal starved mixed elastohydrodynamic lubrication (EHL) theory is hired in the model. The empirical equations for analysing the contact force of rough surfaces that are based on amount of accurate finite element analysis (FEA) of an elastic‐plastic single‐asperity contact over a rigid flat are proposed. Multilevel method is used to solve the modified Reynolds equations, and sweeping column method is used to solve energy and heat conduction equations. The pressure field, the fractional film content, and the temperature field are obtained through the present model. In addition, the influences of train speed, surface roughness amplitudes, and inlet film thickness on the adhesion coefficient are investigated. The results from the present model have been compared with those from flooded analyses for water and oil‐contamination cases. The numerical results show that the inlet film thickness and the train speed had a significant effect on the wheel/rail adhesion ability.

Demand Analysis of Lubricating Oil in Spur Gear Pairs

“…(4) Oil for lubrication increases, but oil for cooling decreases as the modulus increases. (5) As the number of teeth increases, the oil volume for lubrication increases, but the oil volume for cooling decreases. (6) The rangeability of the oil volume for lubrication along the mesh line (i.e., the slope of the curve of the oil volume for lubrication) increases as the transmission ratio increases.…”

“…A review of the published literature shows that the field of gear lubrication has two major research focuses. The first focuses on the state of the lubricating oil film on the meshing tooth surfaces, including the model analysis of EHL, in order to establish the nonlinear relationships among oil film thickness, pressure and density [4]; numerical methods for solving the EHL [5]; and measurement of and experimentation on the contact area [6]. The second group focuses on the use of commercial computational fluid dynamics (CFD) software to simulate the flow state of lubricating oil during the gear meshing process and visualise the flow field of lubricating oil [7].…”

Research Progress of High-Speed Wheel–Rail Relationship

“…In addition, they also analyzed the influence of the different physical properties of water and oil on the adhesion characteristics. They found that the adhesion coefficient decreased faster than that of water in the presence of oil pollution on wheel-rail surface, and explained the causes from the numerical point of view [84][85][86]. Chen H et al developed a three-dimensional calculation model using the mixed lubrication theory to numerically analyze the adhesion characteristics in a water medium.…”

“…The obtained result has theoretical significance, but the prediction of actual wheel-rail adhesion needs careful consideration. To this end, Wu B et al extended their two-dimensional model to a three-dimensional model [88]. The geometric dimensions and actual normal load at the wheel-rail contact point of a CRH2 high-speed train were considered in modeling and analyzing.…”

“…The numerical models discussed above are all aimed at the existence of a single medium between wheel and rail, and there may be more than two or more mixed media on the actual wheel-rail contact surfaces. Therefore, Wu B et al established a wheel-rail adhesion model with a water and oil mixture [88,89]. They believed that the difference between water and oil is mainly in viscosity, and considered that the wheel-rail surface roughness level and the thickness of water-oil film were basically in the same order of magnitude.…”