<p>The influence of train height on aerodynamic characteristics of high-speed train (HST) is significant in crosswind environments. This study employed the improved delayed detached eddy simulation (IDDES) turbulence model to analyze the aerodynamic characteristics of trains with three different heights under a crosswind of 20 m/s. The numerical model was validated through comparison with wind tunnel experimental data. A comprehensive analysis was conducted on the characteristics of the flow field around trains, surface pressure distribution, and aerodynamic loads for trains with different heights. Results indicate that the side force coefficient increased by up to 61.54% with an increase in train height from 3.89 to 4.19 m. Compared with the 3.89 m case, the roll moment coefficient on the head, middle, and tail cars for 4.19 m cases increased by 18.11%, 24.78% and 34.23%, respectively. The increase in train height widens the impact width of the leading car’ s front vortex on the leeward side and intensifies the helical shedding and coupling interactions of two vortices in the wake, leading to an increase in the intensity and extent of wake flow in both vertical and longitudinal directions. Additionally, the increase in height shifted the flow separation point on the leeward side, moving vortices farther from the train, expanding the back-flow region, and intensifying Reynolds stress and turbulent fluctuations on the leeward side, which adversely impacted train stability and safety. The research findings can provide a reference for the design of train configurations and the assessment of dynamic performance in crosswind environments.</p>

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Effect of train heights on aerodynamic performance of high-speed trains under crosswind

  • Xiao-hui Xiong,
  • Li-ying Liu,
  • Guang Chen,
  • Bo Chen,
  • Ru-dai Xue,
  • Kai-wen Wang

摘要

The influence of train height on aerodynamic characteristics of high-speed train (HST) is significant in crosswind environments. This study employed the improved delayed detached eddy simulation (IDDES) turbulence model to analyze the aerodynamic characteristics of trains with three different heights under a crosswind of 20 m/s. The numerical model was validated through comparison with wind tunnel experimental data. A comprehensive analysis was conducted on the characteristics of the flow field around trains, surface pressure distribution, and aerodynamic loads for trains with different heights. Results indicate that the side force coefficient increased by up to 61.54% with an increase in train height from 3.89 to 4.19 m. Compared with the 3.89 m case, the roll moment coefficient on the head, middle, and tail cars for 4.19 m cases increased by 18.11%, 24.78% and 34.23%, respectively. The increase in train height widens the impact width of the leading car’ s front vortex on the leeward side and intensifies the helical shedding and coupling interactions of two vortices in the wake, leading to an increase in the intensity and extent of wake flow in both vertical and longitudinal directions. Additionally, the increase in height shifted the flow separation point on the leeward side, moving vortices farther from the train, expanding the back-flow region, and intensifying Reynolds stress and turbulent fluctuations on the leeward side, which adversely impacted train stability and safety. The research findings can provide a reference for the design of train configurations and the assessment of dynamic performance in crosswind environments.