Study On Flow Field Around High-Speed Train And Thermal Comfort In Compartment

With the continuous increase of running speed of High-Speed Train, train aerodynamic effects will become more obvious. When trains run in heavy snow environment or different track, the air flow around the train will be affected accordingly, which will threaten train safety. It’s necessary to analyze air flow around the train. When we design High-Speed Train, the flow characteristics and the thermal comfort inside the compartment are important. It is important to give reasonable judgment and suitable optimization suggestions in the designing process.Based on the theory of Computational Fluid Dynamics and Computational Heat Transfer, using pre-processing software ICEM CFD and computational fluid dynamics software FLUENT, the flow field around train, the duct resistance and the thermal comfort inside the compartment are studied. The main results are as follows:1. Snow accretion on train bogies is studied. Considering the rotation of wheels, appropriate solutions are proposed to improve the flow field distribution by analyzing the flow field of the original model and the optimization models, so as to get a final optimization. The result shows that, the rotation of wheels has a certain effect on the flow field around bogies, and it’s necessary to consider the rotation of wheels. It’s feasible to improve the flow characteristics by using the three optimizations mentioned in the paper. And they can be combined to optimize the flow field if conditions permit.2. The effect of ballastless track on High-Speed Train aerodynamic characteristics is studied. The train aerodynamic characteristics are numerically simulated by establishing the frame slab track model and the plane slab track model. It shows that, when the train passes through the frame slab track at 300km/h, the surface pressure of the bottom plate and bogie periodically fluctuates due to the existence of the frame slab, and the main frequency of the pressure impulse is next to 16.90Hz. When the train passes through the plane slab track, the surface pressure of the bottom plate and bogie fluctuates a little. And it’s necessary to consider the ballastless track plate and track structure when we simulate the flow field underneath High-Speed Train.3. The duct resistance and the thermal comfort of High-Speed Train are studied. First of all, pressure distribution, air speed distribution and temperature distribution inside the compartment were calculated, then several structural improvements can be proposed.The rational design is finally formed by further analysis and calculation. The results show that, comparing with the upper and the lower intake modes, the duct resistance of the mixed intake mode is more obvious. The flow field in the compartment is relatively stable, and the velocity distribution is more uniform under the mixed intake mode. The three air intake modes contribute little to the pressure in the passenger compartment, and the pressure distributes uniformly in whole passenger compartment. Under the mixed intake mode, the flow of holes locating at both ends of the duct is slightly larger than that of holes in the middle of the duct, which leads to non-uniform temperature distribution in the passenger compartment. The diameter of holes locating at both ends of the duct should be narrowed to 0.5 times, and finally the temperature distribution of the passenger compartment acts more uniformly. The temperature difference in the passenger compartment is within 2℃, and it justifies the optimization.