Study On Heat Transfer Characteristics Of A Disc Brake Of High-Speed Train

Disc brake is the most reliable basic brake measure for high speed train,and the braking performance of disc brake equipment depends mainly on the ability of brake disc and brake pad to bear friction heat,thermal stress and heat dissipation.Under the braking condition,the brake disc and the brake pad produce huge heat because of friction,the temperature of the brake disc rises sharply.The brake disc passes the convection heat transfer,dissipates the huge heat in a short time,reduces the temperature of the brake disc,and improves the braking effect.Therefore,the study of the heat transfer characteristics of the brake disc in the braking process is the key to optimizing the structure of the brake disc,improving the heat transfer performance of the brake disc and ensuring the safe and efficient operation of the high speed train.In this paper,firstly,the heat transfer process of the brake disc is analyzed in the emergency braking condition,and the physical model of the brake disc is simplified to obtain the computational model of the brake disc.Secondly,ICEM is used to mesh the computational domain of the brake disc,and the braking process is simulated by Fluent software.The velocity field and the convection heat transfer characteristics of external surfaces and internal passages of brake disc are obtained.Finally,by analyzing the numerical results,the following conclusions can be drawn:(1)Under the joint actions of the rotation of the axle and the moving of train,the air flow with complex vortex structures is formed around the brake disc,and the magnitude of the vector increases along the radial direction.(2)At the same braking time,the larger the initial braking speed is,the greater the average convective heat transfer coefficient is.In the same braking condition,the convective heat transfer coefficient decreases with the increase of braking time,and the reduction rate of convective heat transfer coefficient decreases with the increase of braking time.The convective heat transfer coefficient of the brake disc is higher in the windward area than the convection heat transfer coefficient of the brake disc in the leeward.The larger the radius of the windward area is,the higher the convective heat transfer coefficient,the smaller the radius of the leeward area is,the higher the convective heat transfer coefficient.(3)The average convective heat transfer coefficient on the flange surface of the brake disc is much higher at the maximum radius than that of the outer surface of the brake disc.At the same braking time,the larger the radius is,the greater the local convection heat transfer coefficient of the outer surface of the brake disc,and the greater the reduction rate of the convection heat transfer coefficient.(4)The average convective heat transfer coefficient of the internal channel of the radiator of the brake disc is higher than the average convective heat transfer coefficient of the disc surface formed the internal channel of the brake disc.The larger the radius is,the greater the local convection heat transfer coefficient of the inner channel of the brake disc,and the greater the reduction rate of the convective heat transfer coefficient.At the same radius,convective heat transfer coefficient on the radiator surface of the brake disc distributed non uniformly along the height direction of the radiator,at mind position,convective heat transfer coefficient is higher than other places.