An IDDES investigation of Jacobs bogie effects on the slipstream and wake flow of a high-speed train

Artikel i vetenskaplig tidskrift, 2020

This study numerically investigates the effects of Jacobs bogies on the aerodynamic behaviors of a high-speed train using improved delayed detached eddy simulation (IDDES) at Re ​= ​3.3 ​× ​105. The results of the numerical simulations have been validated against the experimental data obtained from a previous reduced-scale moving model test and a wind tunnel test. The slipstream velocity, wake flow, underbody flow and aerodynamic drag of the HST are compared between the conventional bogie case and Jacobs bogie case. The results show that the use of Jacobs bogies can reduce the TSI values of the slipstream velocity at trackside and platform positions by 11.07% and 22.40%, respectively, which thereby shows a positive effect on improving the safety level of trackside workers and passengers standing on the platform. The Jacobs bogies are found to decrease the maximum values of the slipstream velocity and turbulence kinetic energy occurring at the intermediate bogie regions beneath the HST by 30.08% and 41.32%, respectively, which is beneficial for weakening the ballast flight phenomenon. The Jacobs bogies significantly narrow the scale of the longitudinal vortex structure in the wake propagation region. Additionally, the application of Jacobs bogies lowers the aerodynamic drag values of the vehicles and contributes to a 10% total drag reduction.