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Numerical investigation of the impact of wall boundaries on aerodynamic noise in high-speed trains
(2026-01-01)
Ma, Zhi Yuan
;
Feng, Qing Song
;
Prapamonthon, Prasert
;
Cheng, Gong
;
Sun, Zhen Xu
As the operating speed of high-speed trains continues to rise, aerodynamic noise has become a critical factor influencing train performance and passenger comfort, especially in confined environments like tunnels. In this study, a comprehensive simulation of the aerodynamic noise generated during the entire ‘open air-tunnel-open air’ transition at 450 km/h was performed using the improved delayed detached eddy simulation (IDDES) turbulence model and overset grid method, with results validated against field measurements. The findings reveal that, compared to open-air conditions, the tunnel environment induces higher-flow velocities around the train, stronger pressure fluctuations on the train surface, and more pronounced vortex shedding in the wake. Sound pressure levels (SPLs) at surface measurement points are typically about 10 dB(A) higher in the tunnel, with the primary differences observed in the 100–300 Hz frequency range, while both scenarios exhibit spectral peaks near 530 Hz. In the bogie region, tunnel noise is dominated by pressure-wave coupling and wall reflections, which amplify low- and mid-frequency components, whereas under open-air conditions, local vortex shedding and wake instabilities prevail, resulting in more high-frequency noise. The web structure contributes to the reduction of aerodynamic noise from the bogie area, with a particularly significant decrease observed in tunnel conditions. Along the tunnel wall, the SPL initially increases and then decreases, reaching a peak of 125.7 dB(A). After exiting the tunnel, the measurement points at Section L in the open air show a reduction of approximately 10 dB(A) compared to the corresponding tunnel-wall points. This study highlights the substantial amplification of low-frequency noise caused by wall confinement and demonstrates the noise-reduction potential of the web structure. The results provide valuable theoretical insights and numerical evidence for aerodynamic noise control in higher-speed train tunnels, offering significant engineering implications.
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Effect of height of noise barriers on sound source characteristics of aerodynamic noise from high-speed trains
(2025-12-01)
Lu, Wei Shuang
;
Huang, Jun Hui
;
Sun, Zhen Xu
;
Prasert, Prapamonthon
;
Guo, Di Long
This paper aims to explore the influence of different noise barrier heights on the sound source generation mechanisms of higher-speed trains (400 km/h) using a combination of delayed detached eddy simulation (DDES) and Ffowcs Williams-Hawkings (FW-H) equations. Four cases are investigated and compared, i.e. 1) no barrier, 2) 2.3 m, 3) 3.3 m, and 4) 4.3 m single-side barriers on a bridge. Numerical results show that the presence of noise barriers causes an increase in sound source intensity ranging from 2.1 to 2.8 dB(A). However, the relationship between the barrier height and the increase in sound source intensity varies across different parts of the train. Compared with the head and frontmiddle cars, the boundary layer is thicker around the rear-middle and tail car areas. A thick boundary layer introduces the influence of the crash wall, causing asymmetry and increases in sound source intensity. This is due to the deceleration region formed between the crash wall and the rail surface, as well as the acceleration region formed by the contraction of the flow channel in the noise barrier, both of which influence the sound source’s characteristics. In addition, higher barriers exacerbate asymmetry and increases in sound source intensity.
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Investigation of aerodynamic shape optimization of cross-sectional body of high-speed train
(2025-12-01)
Prasert, Prapamonthon
;
Sun, Zhen Xu
;
Yao, Shuan Bao
;
Bai, Ye
;
Guo, Di Long
A train body’s cross-sectional shape has a significant impact on aerodynamic drag and operational safety in high-speed trains (HSTs). This study extracts five design variables from a real-world HST body: height, width, side arc radius, arc radius at the connection between the side and the roof, and arc radius at the connection between the side and the train’s bottom. The cross-validated Kriging surrogate model and the genetic algorithm are used to perform two types of aerodynamic optimization, with the cross-sectional area as a constraint. Cross-sectional shapes are optimized in both windless and windy conditions. Numerical results indicate that in a windless environment, the aerodynamic drag coefficient of the whole train is reduced by 2.4%; in a windy condition, the aerodynamic drag coefficient of the entire vehicle is reduced by 2.4%, and the aerodynamic lateral force of the leading car is reduced by 37.8%. These suggest that a flat and wide shape helps to reduce not only overall aerodynamic drag in a windless environment but also aerodynamic load in a windy environment, which can be accomplished by reducing the area of the side wall and top region, lowering the train body’s height, increasing its width, and lowering the radius of the side and top arcs.
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