The convective heat transfer characteristics of the track surface on which wheels roll over periodically

Abstract

The convective heat transfer coefficient on the rail surface is an important parameter to determine the temperature field of the wheel/rail contact region, especially at the condition that train operates normally and the condition that an eddy current brake is used. Because of the complex configuration of a real wheel/rail contact system, it is hard to build a model with similar geometry as the real one. In this paper, a simple experimental model is used to obtain the convective heat transfer coefficient on a circular track surface on which the wheels pass periodically. In the experimental processes uniform heat flux is applied on the track surface, and the six types of the wheels are used. The results show that when the heat transfer coefficient is presented regarding to the wheel center velocity or angular velocity, it is dependent on the wheel diameter. For the same wheel diameter, the heat transfer coefficient has a parabolic distribution characteristics regarding to the wheel center velocity, which means the heat transfer coefficient increases firstly and then decreases as the wheel center velocity increases. The maximum value of the heat transfer coefficient is independent of the wheel diameter. It is hard to find a correlation between Nusselt number and Reynolds number for the wheels with different diameters. The significant characteristic is that the frequency of the wheels pass takes a major role on the heat transfer coefficient. Therefore, the heat transfer coefficient can be correlated with the frequency of the wheels that run over the circular track.