Experimental And Numerical Study Of Transient Convective Heat Transfer Characteristics On The Surface Of The Rail During Train Passing

With the increasing speed and axle load of the train,the wheel/rail contact fatigue is more and more serious.And the friction heat generated in wheel/rail contact surface is increased greatly.The temperature of the rail will increases significantly if the friction heat is not lost timely and effectively,it causes the chemical and physical characteristics change of rail material,decreases the material strength and accelerates material wear.Even more it will leads to crack and peel and other destroy of the rail.Due to the convective heat transfer is an important form of the heat convection of the rail,the transient convection heat transfer coefficient directly affect the degree of heat dissipation of the rail.Therefore,the paper focuses on the transient convection heat transfer characteristics at rail surface when the train passing over the rail.It is helpful to analyze accurately the transient heat transfer of the rail surface.The paper analyzes the transient convection heat transfer characteristics through experimental and numerical methods.In the paper,the experiment system is designed according to CRH5 train model and similar principle.And the physical and mathematical model of the rail heat transfer are established,at the same time,the reasonable computational domain is selected and the mesh is generated by using three-dimensional infinite interpolation method.At last,temperature and velocity fields of rail surface are calculated.The main results were obtained as follows:(1)The relationship between the average convective heat transfer coefficient and the velocity of train shows a liner trend,the average convective heat transfer coefficient increases with increasing the velocity of train.(2)The heat transfer coefficient on the main surface of the rail head was greater than the heat transfer coefficients on the side surfaces of the rail head,even more the heat transfer coefficient on the side surface of rail contacted with wheel rim was slightly lower than the heat transfer coefficient on the opposite side surface of the rail.(3)When the rolling wheels pass over the rail,the tendency of the transient heat coefficient on the surfaces of the rail was ascend in first and descend at last.