Numerical investigation on the aerodynamic drag reduction based on bottom deflectors and streamlined bogies of a high-speed train

Abstract

The complex structure of the bottom of a high-speed train is an important source of train aerodynamic drag. Thus, improving the bottom structure is of great significance to reduce the aerodynamic drag of the train. In this study, computational fluid dynamics (CFD) based on three-dimensional steady incompressible Reynolds-average Naiver-Stokes (RANS) equations and Realizable k-ε turbulence model were utilized for numerical simulations. Inspired by the concept of streamlined design and the idea of bottom flow field control, this study iteratively designed the bogies in a streamlined shape and combined them with the bottom deflectors to investigate the joint drag reduction mechanism. Three models, i.e., single-bogie model, simplified train model, and eight-car high-speed train model, were created and their aerodynamic characteristics were analyzed. The results show that the single-bogie model with streamlined design shows a noticeable drag reduction, whose power bogie and trailer bogie experience 13.92% and 7.63% drag reduction, respectively. The range of positive pressure area on the bogie is reduced. The aerodynamic drag can be further reduced to 15.01% by installing both the streamlined bogie and the deflector on the simplified train model. When the streamlined bogies and deflectors are used on the eight-car model together, the total drag reduction rate reaches 2.90%. Therefore, the proposed aerodynamic kit for the high-speed train bottom is capable to improve the flow structure around the bogie regions, reduce the bottom flow velocity, and narrow the scope of the train’s influence on the surrounding environment, achieving the appreciable reduction of aerodynamic drag. This paper can provide a new idea for the drag reduction of high-speed trains.

Keywords

high-speed train / numerical simulation / drag reduction / deflector / streamlined design

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