The Experimental Study Of The Similar Convective Heat Transfer Characteristics At The Rail Surface

When the train runs on the rail at a high speed, the temperature of the wheel/rail contact area changes rapidly. It makes the rail strength reduction and changes with the organizational structure, aggravates the rail damage phenomenon, such as the wear and formation of cracks on the rail surface, even threatens the safety of the train. However, the surface of the rail temperature closely links with the convection heat transfer coefficient of the rail surface. Therefore, this article researches on the heat transfer characteristics by the experimental when the train passes over the rail surface.Based on the analysis of heat transfer model on the rail surface, it designs an experiment to simulate the heat transfer characteristics of the rail surface passed over the train, and set up an experimental platform which agrees with the experimental principle. The experiments were performed with four types of the test wheels having different diameters when the test wheels pass the rail surface periodically. The heat transfer characteristics on the test rail surface are obtained at the conditions that the test wheels roll over the orbit. In order to extend the experiment results to the real case, a key parameter for the data processing, namely the characteristic length is proposed. On the basic of the characteristic length, the experiment data can be cast into a correlation. The convective heat transfer coefficient and characteristic of the real rail surface when a train passes over can be obtained from the correlation.The research results are as follows. ① when different diameters of the test wheels roll over the orbit periodically, the relationship between the average convective heat transfer coefficient and the center velocity of the rolling wheel shows a parabolic trend, which increases firstly and then decreases. with the same linear velocity, the larger diameter of the wheel is, the smaller the average convective heat transfer coefficient is. ②The convective heat transfer characteristics of the rail are determined by not only the centre velocity of the rolling wheel but also the frequency of the rolling wheel passing the rail and the rotation frequency of the rolling wheel. ③It is found the characteristic length which determines the heat transfer characteristics of rail, reached the experimental correlations and obtained the convective heat transfer coefficient and characteristic of the real rail surface when train passes over.