Numerical investigation on the aerodynamic effects of underbody blockage ratio on high-speed train using full-housing bogie*

Most of the air resistance in high-speed train (HST) is generated by the underbody, which includes the bogies [1]. With international interest in increasing the speed of HST, significant research is being conducted on improving bogie designs [2].

In this study, the shape of full-housing bogie (FHB) was suggested, and its effects on the underbody flow field of HST were numerically examined. FHB was designed based on the underbody blockage ratio (BR) with consideration of gauge limits of vehicle. 3 designs of FHB with BR = 0%, 50%, and 75% were selected to compare drag coefficient and near-train velocity magnitude with the conventional bogie.

KTX-Cheongryong, the next-generation HST of South Korea, was used as a baseline model with the speed of 400 km/h. Although the installation of FHB increased the underbody BR, the aerodynamic performance such as mitigating the wake turbulence, reducing shear stress due to the slower growth of the boundary layer, was improved compared to the conventional bogie. In particular, FHB with BR = 50% showed 13.3 % lower air resistance than the conventional bogie.