Convective Heat Transfer Characteristics At The Rail Surface Due To Train Passage

With the increase of train speed and axle load, in addition to braking and acceleratingtraction frequently, the wheel-rail contact surface thermal fatigue phenomenon became themain problems of rolling contact fatigue. Specific performance occurred in the change of themetallurgical structure of the rail surface material, such as characteristic changes, reducedstrength, increased wear and tear, peel and crack formation between wheel and rail, so it isaffecting the stability of the track, and had a negative impact on the safe operation. But thekey factors: the rail surface temperature, its size depends on the convection heat transfercoefficient of rail surface. Therefore, when the train passes over the rail, the convective heattransfer characteristics on the surface of rail become very important to determine thetemperature change of the rail. So, find out the convective heat transfer coefficient on the railsurface has theoretical significance and practical significance to extend the service life of therail track and ensure the safe operation of the railway. Therefore，this paper focuses on thestudy of the convective heat transfer characteristics at the rail surface due to train passage.The main contents include establish the experiment bench on rail surface heat transfer, aproper experimental wheel design, get the rail surface heat transfer characteristics by theexperimental method, establish the flow and heat transfer model, Then use the FLUENT tosimulate the experiment under different conditions after that.The main conclusions were drawn as follows.(1) When the speed of the rolling wheel isbelow a certain value, the average heat transfer coefficient increases with an increase in thespeed of the wheel. When the speed of the wheel increases further, the average heat transfercoefficient decreases greatly, it is a parabolic function with respect to the center velocity ofthe wheel.(2) Based on the frequency of the rolling wheel passing the rail, the experimentalresults can be extrapolated to the real case. For an existing configuration of a real train, thecritical train velocity is about182km/h, and the mean heat transfer coefficient value is146W/(m2·K).(3) Through the numerical simulation by FLUENT, the mean heat transfercoefficient of rail surface between is proportional to the wheel speed.