Influence of wind tunnel size on aerodynamic performance of high-speed train

The influence of wind tunnel dimensions on the aerodynamic performance of high-speed trains was investigated by single-factor variable method. The unsteady flow fields were analyzed by three-dimensional, incompressible Navier-Stokes equation based on the detached eddy simulation(DDES) method, and the aerodynamic performance of high-speed train at 1:8 scale model in different wind tunnel sizes was obtained. The reliability of the method was validated through comparison with wind tunnel test result. The results indicate that as the wind tunnel dimensions decrease and the blockage ratio between the model and the wind tunnel increases, the airflow acceleration around the train becomes more pronounced. As a result, the positive and negative pressures on the train surface increase, which enhances the vortex strength, and leads to an increase in aerodynamic forces on the train. Specifically, when the wind tunnel blockage ratio increases from 0.61% to 4.17%, the aerodynamic drag on the train increases by 15%. To obtain more accurate test results, wind tunnel experiments for high-speed trains should preferably be conducted in larger-sized wind tunnels, to reduce the interference of the wind tunnel blockage effect on the test results. © 2024 Central South University of Technology. All rights reserved.