Abstract The effect of lowering the ground clearance, on train aerodynamics is investigated using IDDES. The high speed train geometry with its full underbody complexity is used in the investigation. The clearance is reduced by installing extra panels on the track. The numerical results are verified and validated by a grid independence study and experimental data. This work shows that, when lowered the clearance, the underbody velocity at the head car decreases, while the underbody velocity at the middle and tail car increases. The reduced clearance barely affects the time-averaged slipstream at 3 ​m away from the center of track. However, at a closer distance to the train body, the difference in velocity is observed to reach up to 50% between the two clearance configurations and the clearance has an opposite effect on the trackside and platform slipstream. Based on the analysis of ensemble-averaged slipstream, lowering the underbody clearance, the characteristic air speed at the trackside and platform height increases by 2.0% and 6.7%, respectively. The total drag is almost unaffected by the clearance, but the changed distribution of the drag indicates a larger drag depends on the bogie structure if longer grouped train is used. The total lift decreases 25.9% after the clearance is reduced. Specifically, 4.1% of the negative lift is increased at the head car, while the positive lift decreases 92.7% and 1.8% for the middle and tail car, respectively. Overall it is shown that reducing the underbody clearance barely affect the slipstream at standard positions, but affects more aerodynamic loads of the train.

中文翻译：

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降低车底间隙对高速列车空气动力学的影响

摘要 使用 IDDES 研究了降低离地间隙对列车空气动力学的影响。在调查中使用了具有完整底部复杂性的高速列车几何形状。通过在轨道上安装额外的面板来减少间隙。数值结果通过网格独立性研究和实验数据得到验证和验证。该工作表明，当间隙降低时，头车处的车底速度降低，而中车和尾车处的车底速度增加。减少的间隙几乎不会影响距离轨道中心 3 m 处的时间平均滑流。然而，在距离火车车身更近的地方，观察到两种间隙配置之间的速度差异高达 50%，间隙对轨道侧和平台滑流具有相反的影响。基于整体平均滑流分析，降低车身底部间隙，轨道侧和平台高度的特征空速分别增加2.0%和6.7%。总阻力几乎不受间隙的影响，但阻力分布的变化表明，如果使用更长的组合列车，则更大的阻力取决于转向架结构。间隙减小后总升力下降25.9%。具体来说，头车的负升力增加了 4.1%，而中间和尾车的正升力分别减少了 92.7% 和 1.8%。