Effect of bionic sphere form on drag reduction of high-speed maglev train

Using IDDES turbulence model based on SST k-ω equation, different bionic sphere structures were set at the streamlined part of the high-speed maglev train to simulate its drag reduction performance. The results show that the bionic sphere structure can not only effectively reduce the wake velocity and weaken the overall strength of the wake, but also restrict the development of the wake vortex and reduce the radiation range of the wake vortex. The sphere structure reduces the area of the high-speed flow area at the separation position of the tail car flow, effectively delays the burst of turbulence, reduces the turbulence intensity and narrows the thickness of the boundary layer. The bionic sphere structure has an adsorption effect on the slipstream, so that the high-speed area is concentrated closer to that of the nose of the tail car, and the velocity fluctuation of the wake becomes smaller. The difference of sphere shape has a great impact on the flow field structure. Compared with the convex spherical structure, the concave spherical structure has a more significant weakening effect on the wake intensity, a better effect on the boundary layer at the flow separation position, and a stronger adsorption capacity for slipstream. The setting of convex spherical structure and concave spherical structure can reduce the aerodynamic drag of the tail car by 7.64% and 14.58% respectively, but increases the aerodynamic drag of the head car by 2.33% and 1.16% respectively. © 2023 Central South University of Technology. All rights reserved.