Study On Convective Heat Transfer Coefficient Of High-speed Train Wheels

Rail and wheel are important parts of railway transportation.As the train speed is faster and faster,the carrying load gets bigger and bigger,the wheel-rail rolling contact appears over fatigue,the mechanical wear is serious,and the relative sliding between the wheel and the rail produces a lot of friction heat,which intensifies the wheel heat damage.The area where the friction heat is generated in the wheel-rail contact area is very small,which causes the local surface temperature of the wheel to rise rapidly,which has great influence on the thermal stress,creep rate and adhesion coefficient of the wheel and rail,and reduce the stability and safety of the train.In this paper,the numerical simulation method is used to analyze the convection process between the wheel surface and the surrounding air.The main content includes: the analysis of wheel surface heat transfer characteristics;the simplification of physical model of wheel and rail;the establishment of computational domain of wheel and rail;the computational domain mesh generation by using ICEM CFD software.In order to obtain the convective heat transfer coefficient and the transient convective heat transfer coefficient of the wheel surface,the calculations are carried out to obtained the temperature field and velocity field during the heat transfer process between the wheel surface and the surrounding air by using STAR-CCM+.The main research results are as follows:(1)The average convective heat transfer coefficient of the wheel surface is affected by the running speed of the train and has a parabolic relationship with the train speed.When the velocity is lower than a certain value,the average convective heat transfer coefficient increases with the velocity increasing,and when the velocity is higher than a certain value,the convective heat transfer coefficient decreases with the increase of the train speed.(2)The average convective heat transfer coefficient of the wheel tread is higher than that of the wheel rim at the speed of less than 40 m/s in the study condition.The average convective heat transfer coefficient of the wheel tread is lower than the wheel rim when the speed is higher than 40 m/s.(3)When the velocity is lower than 50 m/s,the average convective heat transfer coefficient of the inner surface of the wheel is close to the outer surface.When the velocity is higher than 50 m/s,the average convective heat transfer coefficient of the inner surface is higher than that of the outer surface.(4)When the running time is about half the wheel cycle,the transient convective heat transfer coefficient of wheel tread,rim,inner surface and outer surface decreases with time,and then increases with time.