车辆通风式制动盘内部通道对流换热研究综述

The research results of convective heat transfer in the internal channel of ventilated brake disc were summarized, and the influences of different structural designs on the heat transfer were analyzed from three aspects: mass flow, convective heat transfer coefficient and effective heat dissipation surface area. The analysis and detection methods of the convective heat transfer were reviewed at home and abroad from three aspects: analytical method, numerical analysis method and experimental test method. Research results show that there are two main flow modes in the channel of radial blade brake disc: the backflow caused by the airflow separation adjacent to the suction side of the blade and the secondary flow rotating in the radial channel. Restraining the formation of the backflow zone can increase the mass flow rate of the pumping air and make the temperature distribution in the channel more uniform. The secondary flow promotes the development of air mixed flow and turbulence between the channels, strengthens the local shear stress and improves the heat dissipation performance of the brake disc. In addition, the comprehensive application of jet impingement strengthening methods (multi-beam, swirl and multi-directional jets, etc.), high porosity and columnar-like structure optimization design can also change the flow state of the fluid in the channel. These measures increase the fluid disturbance in the channel, thin the thermal boundary layer and increase the velocity gradient near the wall, which effectively improve the convective heat transfer coefficient of the brake disc and enhance the heat dissipation capacity. The results obtained by the analytical method and numerical analysis method have strong theoretical reference, but the results obtained by the experimental test method are closer to the changes of the actual internal temperature and air flow rate of the brake disc. Therefore, if the three methods can be seamlessly combined to achieve complementary advantages, it will have the most scientific research value. Besides, in order to obtain the maximum heat dissipation efficiency, the friction pressure drop and flow resistance in the channel are often ignored in optimizing the brake disc structure of high-speed vehicle. Therefore, how to balance the relationship among heat dissipation, frictional pressure-drop and flow resistance needs further exploration and research.