Experimental Study Of The Heat Transfer Performance Of The Brake Disc Inner Channel With Straight Arc Fins For High-Speed Train

In recent years,with the rapid growth of China’s economy,vigorously developing high-speed train has become the first choice to ease the tension of railway transport capacity.The increase of train speed has a higher demand for braking capacity.There will be much more temperature rise in the brake disk as well as wheel and rail when the high-speed train brakes at high speed,the wear,fatigue and heat damage are more severe,the problem of poor braking effect has also become increasingly serious.Train braking capacity is the most important problem in its safe operation,and it is also the key technology to be solved urgently.Therefore,the convection heat transfer performance on the inner channel surface of the brake disc directly affects the degree of heat dissipation of the brake disc during braking.The paper mainly studies the heat transfer characteristics of the inner channel of the radial straight rib brake disc of the high speed train,and the results can provide some reference for the design and selection of the high speed rail brake disc.In the actual operation of the high-speed train,if the ground is selected as the reference object,the brake disc rotates along with the wheels,and the high-speed train also has a forward translation speed.In order to simulate the actual movement model of the brake disc,the paper designs and tests the experimental specimen of the brake disc,and the roller and the experimental brake disc are mounted on the same shaft.Let the experimental brake disc rotate with the roller in the simulated ground circular orbit.In the simulation movement,the brake disc rotates on the one hand with the roller at the same rotational speed.On the other hand,the brake disc and the roller are mounted on the rotating arm of the spindle on the circular track.In the experiment,the main shaft was rotated by the motor,so that the roller and the brake disk were given a translational speed to move on the track to obtain more accurate experimental data.The dissertation mainly studies three parts;firstly,the brake disc experimental platform is designed,and the problem that the experimental wheel is easy to fall off during the measurement operation is improved,making the measured value more accurate during the experiment.Secondly,the naphthalene layer of the internal channel of the experimental brake disc is made smooth and dense by using cast naphthalene mold to cast naphthalene on the disc surface and ribs of the brake disc specimen,respectively,so that the final measured data is close to the actual situation.Thirdly,by designing experimental brake disc specimens with different geometrical parameters,the average Nusselt number variation of the inner channel surface of the brake disc was obtained by naphthalene sublimation technology.The naphthalene sublimation heat and mass transfer analogy principle is used in the study to obtain the average convective heat transfer characteristics of the brake disc inner channel with straight arc fins.The effect of the fin parameters as well as the effects of angular velocity and characteristic speed of brake discs on the average convective heat transfer characteristics were studied.The main results of this study are as follows:The average Nusselt number of the inner channel of the sector-shaped cylinder straight rib brake disk increases with the increase of the Reynolds number,and the relationship between the two is obtained.There is a corresponding correlation between the convection heat transfer coefficient and the angular velocity of the inner channel of the sector-shaped cylinder straight rib brake disc,that is,the convection heat transfer coefficient of the inner channel of the brake disc increases with the angular velocity.There is a positive correlation between the convection heat transfer coefficient and the characteristic velocity of the inner channel of the sector-shaped cylinder straight-rib brake disc specimen.That is,the convection heat transfer coefficient of the inner channel of the brake disc increases with the increase of the characteristic speed,and the relationship between them is expressed.The higher the characteristic speed,the better the convection heat transfer capability of the inner channel of the brake disc.