Aerodynamic drag reduction of streamlined bogie and bottom deflector of high-speed train

In order to further reduce the aerodynamic drag on the bottom of higher-speed train, the idea of bottom flow control was applied on the bogie of CR400AF type high-speed train. By covering the original components with additional lightweight and easy-to-shape materials, the streamlined design of bogie was achieved. Validation tests and numerical simulation on the streamlining of the bogie components and the comprehensive drag reduction of the deflector were carried out. The test model with a streamlined bogie with or without deflector was selected. The error between test and simulated drag values at all three test speeds was less than 10%, verifying the reliability of the numerical simulation. The test model with deflector has reduced the drag compared to the test model without deflector. In simulation, realizable k-Ε turbulence model is adopted. Cartesian mesh is used to mesh computational domain with simplified train head and bogie. Prismatic layer mesh is used to capture the boundary layer viscous effect. The thickness of the first layer mesh is controlled to ensure that the y+ value could meet the wall function requirements. After the mesh independence test of the steady-state open-air operation simulation, the aerodynamic drag reduction characteristics of the streamlined bogie in combination with deflector are investigated. The aerodynamic drag, pressure distribution and flow field structure of the original bogie/ simplified body, streamlined bogie/simplified body, streamlined bogie/simplified body/deflector are compared and analyzed. The numerical simulation results show that the streamlined bogie has a good drag reduction effect compared with the original bogie, with a drag reduction rate of 1.08% at 400 km/h. After the combined application of the streamlined bogie and deflector, the flow field structure of the bogie area has been significantly improved, the total aerodynamic drag is reduced by 5.87%. © 2024, Central South University Press. All rights reserved.