Meandering airflows beneath the underbody of a train model including bogie (LES of large-scale flow structure around real-shaped train model)

Abstract

In this study, a large-eddy simulation (LES) is conducted to investigate meandering airflows generated throughout the underbody of a real-shaped train model in open air. In our previous study, this was shown by an LES of airflows around a simplified train model. The shape of the underbody affects the flow. However, thus far, no systematic analyses that consider bogies have been conducted. Our experimental results qualitatively reproduced the power spectra of lateral velocity fluctuations in the underbody obtained using a 1:8.4-scale train model on a moving belt in a wind tunnel. Results on the effects of various bogie shapes suggested that the meandering flow was primarily affected by the time-averaged profile of streamwise velocity. Thus, the effects of the bogie shape on airflow are considerable. Comparing bogie shapes with and without a side cover, that without a side cover generated meandering airflow with a slightly smaller peak frequency than that with a side cover, and a completely smooth bogie generated no meandering airflows. It was confirmed that this LES was useful as a technical tool to develop measures to reduce meandering airflows around high-speed trains.