Abstract
The bogie is a unique component exclusive to railway locomotives and rolling stock, and the simplified level of the bogie model directly influences the distortion and accuracy of the experimental results obtained. In this study, the effects of bogie simplified thresholds (T) are numerically investigated employing the improved delayed detached eddy simulation method. Three bogie configurations, comprising complex, moderate, and simple setups, were proposed for a 1/8th scale train model, each featuring different thresholds. The numerical algorithm was validated through a wind tunnel test, with a focus on aerodynamic loads and pressure distribution. The results indicate that as the bogie simplified threshold T increases, the drag and lift forces of each car increase. The head car exhibits a reduction in both lateral force and rolling moment coefficients, whereas the middle car sees a marginal increase, and the tail car maintains unchanged coefficients. As the bogie simplified threshold T increases, the blockage effects of the bogie cavity diminish under crosswinds, leading to decreased airflow impact on the bogie. However, the airflow impact on the vehicle bottom and the bogie cavity's end faces intensifies. The simple setup (T = 200 mm), due to neglecting significant geometric features, exhibits poorer agreement in surface and surrounding flow fields around the train, compared to the other two configurations. Therefore, to guarantee precise predictions accounting for both drag coefficients and detailed bottom flows, it is recommended to maintain the bogie simplified threshold at T = 100 mm at minimum. This study offers prospective insights into modeling detailed components for rail vehicles during wind tunnel experiments.
Published Version
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