Key Takeaways & Executive Findings
- •• A leeward winglet deflection angle of 90° optimally reduces the overall overturning moment by 27.6% compared to the baseline high-speed train model. • Enhancing negative surface pressure on the leeward side via passive flow control with winglets improves train resistance to crosswind-induced overturning. • The study analyzes five deflection angles across head, middle, and tail cars, providing a comprehensive assessment of aerodynamic loads and flow field modifications. • The findings offer practical guidance for aerodynamic design and optimization of high-speed trains operating under strong crosswind conditions.
Abstract
The stability of high-speed trains under crosswind conditions has become a key consideration in aerodynamic design. As running speeds continue to increase and car body weight decreases, crosswinds pose a greater risk to train safety, significantly lowering the critical wind velocity. Therefore, developing strategies to enhance crosswind stability is essential. This study focuses on the leeward region adjacent to the train body, where separated flows with large vortices generate significant negative surface pressure. Enhancing this negative pressure distribution is proposed as a potential method to improve a train’s resistance to overturning. To achieve this, winglets are installed on the leeward side as a flow control measure, and their effects at different deflection angles are evaluated. The influence of five deflection angles on the leeward-side flow field and aerodynamic loads is analyzed, considering the head, middle, and tail cars. Results indicate that a deflection angle of 90° optimally reduces the overall overturning moment by 27.6% compared to the baseline model in a three-car configuration. These findings highlight that optimizing the winglet deflection angle to approximately 90° can significantly enhance a train’s resistance to overturning, offering valuable insights for aerodynamic optimization in strong wind conditions.
1. Introduction
High-speed trains operating in windy environments experience significant aerodynamic forces and moments influenced by crosswind speeds. As train speed increases under such conditions, aerodynamic loads grow, reducing operational stability and increasing the risk of overturning and derailment [1−3]. Moreover, the use of lighter train bodies at higher speeds results in a smaller anti-overturning moment due to reduced weight [4]. Therefore, investigating the aerodynamic characteristics of high-speed trains under crosswind conditions is crucial.
The aerodynamics of a high-speed train (HST) is highly influenced by both its geometric shape and the dynamics of the surrounding airflows [5−10]. Previous work confirms that the windbreak wall has good shielding effect on the train aerodynamic performance [6, 11]. In addition, key design parameters influencing train aerodynamics include the body cross-section, streamlined head, bogie, pantograph, and windshield. The aerodynamic performance of high-speed trains, particularly aerodynamic loads and flow field structures, is directly affected by these components [12−16].
Several studies have examined the impact of train geometry on aerodynamics under strong crosswinds. CHEN et al [13] analyzed the effects of varying streamlined head lengths, focusing on surface pressure distribution, vortex formation, velocity field variations, and aerodynamic coefficients. In recent years, researchers have extensively optimized car body geometry to enhance train stability in crosswinds [14]. Furthermore, several studies have examined the impact of various train components, such as pantographs and bogies, on the aerodynamic performance of high-speed trains under crosswind conditions [15]. Additionally, researchers have explored geometric optimization strategies to enhance aerodynamic stability [16]. Therefore, conventional aerodynamic shape optimization methods are approaching their limits.
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HUANG Feng-yi, SHANG Wen-fei, ZHANG Jie, KRAJNOVIĆ Siniša (2025). Optimization of crosswind stability for high-speed trains: Aerodynamic analysis of leeward winglet deflection angles. Journal of Central South University. https://doi.org/10.1007/s11771-025-6036-x
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Frequently Asked Questions
What is the optimal winglet deflection angle for improving crosswind stability of high-speed trains?
The study found that a winglet deflection angle of 90° optimally reduces the overall overturning moment by 27.6% compared to the baseline model in a three-car configuration, significantly enhancing the train's resistance to overturning.
How do leeward winglets improve high-speed train stability under crosswinds?
Leeward winglets act as passive flow control devices. They modify the separated flow and large vortices on the leeward side, enhancing the negative surface pressure distribution, which increases the anti-overturning capability of the train.
Which train sections are considered in the aerodynamic analysis?
The analysis considers the head, middle, and tail cars of the high-speed train, evaluating the influence of winglet deflection angles on the leeward-side flow field and aerodynamic loads across the entire three-car configuration.
What is the significance of enhancing negative pressure on the leeward side?
Enhancing negative pressure on the leeward side is proposed as a method to improve a train's resistance to overturning. A stronger negative pressure distribution can increase the net aerodynamic force that counters the overturning moment caused by crosswinds.
What are the practical implications of this research for high-speed train design?
The findings provide valuable insights for aerodynamic optimization in strong wind conditions, suggesting that installing winglets with an optimal deflection angle of around 90° on the leeward side can significantly improve train safety and stability without major geometric changes.
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