Aerodynamic characteristics of a high-speed train exposed to heavy rain environment based on non-spherical raindrop

Maruyama, Yu; Liu, Jiali; Dai, Zhiyuan

doi:10.1016/j.jweia.2021.104532

Cited by 26 publications

(8 citation statements)

References 23 publications

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“…When trains cross viaducts in wind and rain environments, the variation of the flow field surrounding the train will further sophisticated, owing to the effect of raindrops on the airflow disturbance (Chen et al , 2016). Fall-off raindrops driven by crosswinds impact the surface of the running trains and collide and splash on it, which makes raindrops cover and alter the roughness and unevenness of the train surface, affecting the aerodynamic loads suffered by the train (Yu et al , 2021). Caused by multifactor, safety problems of trains running on the viaduct in strong crosswind and rain conditions are particularly prominent.…”

Section: Introductionmentioning

confidence: 99%

Influence of wind and rain environment on operational safety of intercity train running on the viaduct

Zeng

Huang

et al. 2023

HFF

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Purpose Based on the aerodynamic loads and dynamic performances of trains, this study aims to investigate the effect of crosswinds and raindrops on intercity trains operating on viaducts to ensure the safe operation of intercity railways in metropolitan areas. Design/methodology/approach An approach coupled with the Euler multiphase model as well as the standard k-ɛ turbulence model is used to investigate the coupled flow feature surrounding trains and viaducts, including airflow and raindrops, and the numerical results are validated with those of the wind tunnel test. Additionally, the train’s dynamic response and the operating safety region in different crosswind speeds and rainfall is investigated based on train’s aerodynamic loads and the train wheel–rail dynamics simulation. Findings The aerodynamic loads of trains at varying running speeds exhibit an increasing trend as the increase of wind speed and rainfall intensity. The motion of raindrop particles demonstrates a significant similarity with the airflow in wind and rain environments, as a result of the dominance of airflow and the supplementary impacts of droplets. As the train’s operating speed ranged between 120 and 200 km/h and within a rainfall range of 20–100 mm/h, the safe operating region of trains decreased by 0.56%–7.03%, compared with the no-rain condition (0 mm/h). Originality/value The impact of crosswind speeds and rainfall on the train’s aerodynamic safety is studied, including the flow feature of crosswind and different particle-sized raindrops around the train and viaduct, aerodynamic loads coefficients suffered by the intercity train as well as the operating safety region of intercity trains on the viaduct.

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Section: Introductionmentioning

confidence: 99%

Influence of wind and rain environment on operational safety of intercity train running on the viaduct

Zeng

Huang

et al. 2023

HFF

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“…For investigating train aerodynamic characteristics using CFD analysis carried in 3D models with different types of meshes; namely polyhedral [9], hexahedral [10] [11], tetrahedron or hybrid mesh type [12]. The majority of research in the investigation of the aerodynamic characteristics of high-speed trains has been carried out using structured mesh because it produces better results than unstructured mesh [13].…”

Section: Introductionmentioning

confidence: 99%

Influence of mesh refinement on the accuracy of numerical results for the Next- Generation High-Speed Train Aerodynamics

Arafat¹,

Ishak²,

Mohammad³

2023

Preprint

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One of the critical issues is the accuracy of numerical simulations using Computational Fluid Dynamics, which is dependent not only on the appropriate flow physics but also on grid generation. In this study, the Richardson extrapolation method was used to investigate the effect of mesh refinement on the accuracy of simulation results for aerodynamic loads and the flow structure around a Next-Generation High Speed train (NG-HST). For the numerical simulation, the commercial Ansys software was used with an SST-based Delayed-Detached Eddy turbulence model. The simulation was carried out with the DLR NG-HST train model. Richardson Extrapolation (RE) and the grid convergence index method were applied using three different mesh resolutions (fine, medium, and coarse). The results obtained from the simulation compared with the previous study. The results of RE showed that the error for drag and moment coefficient was less than 1.5%, while the error for lift was around 7% in terms of predicted value. Furthermore, it was discovered that using a small number of mesh elements improved accuracy over the earlier study. Because it agrees well with previous work, this may conclude that it is possible to predict aerodynamic characteristics on a CFD simulation with a small number of mesh elements.

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“…Aerodynamic characteristics of high-speed trains have become a hot research topic in recent years, especially with the increasing running speed of trains (Yu et al 2021). Due to the shape of the head car, various operating conditions and the high turbulence, the flow around the high-speed trains is complex.…”

Section: Introductionmentioning

confidence: 99%

On the Scale Size of the Aerodynamic Characteristics of a High-Speed Train

Chang

Qin

et al. 2022

JAFM

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In the wind tunnel test of trains, the scale size changes the Reynolds numbers of trains, which may affect the aerodynamic characteristics of the train. Based on computational fluid dynamics (CFD), numerical models of train aerodynamics with five different scale sizes are established. The five different scale sizes are λ=1/1, 1/2, 1/8, 1/16 and 1/25, respectively, and the aerodynamic characteristics of trains running in the open-air operating condition and crosswind operating condition with different scale sizes are numerically simulated. The results show that the pressure drag coefficients and pressure lift coefficients of the train tend to decrease with the decrease of the scale size. In the open-air operating condition, compared with the full-size train, the pressure drag coefficient of the 1/25 th scaled train is less by 14.4%, and the pressure lift coefficients of the head car, middle car and tail car change 16.1%, 46.6% and 12.3%, respectively. The scale size affects the velocity gradient near the train surface and the position of flow separation changes. The decrease of the scale size leads to the decrease of Reynolds numbers and the increase of viscous drag coefficient. When the scale size is 1/25, the viscous drag coefficient of the train is 0.186, which is 48.6% larger than the one of the full-size train.Compared with the open-air operating condition, the trend of the pressure drag coefficients and viscous drag coefficients is consistent except for the head car in crosswind operating condition when the scale size decreases. In the range of scale size λ between 1/1 and 1/25, the aerodynamic drag coefficient of the head car, middle car and tail car increase with the decrease of scale size, and the difference in the aerodynamic drag coefficient of the train is 12.9%. In addition, the train's aerodynamic lift coefficient shows an increasing trend with the decrease of scale size.

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Aerodynamic characteristics of a high-speed train exposed to heavy rain environment based on non-spherical raindrop

Cited by 26 publications

References 23 publications

Influence of wind and rain environment on operational safety of intercity train running on the viaduct

Influence of wind and rain environment on operational safety of intercity train running on the viaduct

Influence of mesh refinement on the accuracy of numerical results for the Next- Generation High-Speed Train Aerodynamics

On the Scale Size of the Aerodynamic Characteristics of a High-Speed Train

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