On the Reynolds-Averaged Navier-Stokes Modelling of the Flow around a
                        Simplified Train in Crosswinds

Li, T.; Zhang, J.; Rashidi, Mohammad Mehdi; Maruyama, Yu

doi:10.29252/jafm.12.02.28958

Cited by 17 publications

(10 citation statements)

References 31 publications

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“…It can accurately solve the viscous sublayers near the wall, and the accuracy of the flow near the train surface is high. It is widely used in the numerical simulation of train aerodynamics and provides the numerical results of aerodynamic forces in good agreement with the wind tunnel test results (Li et al 2019a).…”

Section: Turbulent Modelmentioning

confidence: 89%

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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Section: Turbulent Modelmentioning

confidence: 89%

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

Chang

Qin

et al. 2022

JAFM

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“…A sliding wall is set on the track wall to simulate the relative motion between the train and the track. The turbulence model selects the RNG k − two-equation turbulence model [22,23]. The calculation method adopts the SIMPLE [Semi-Implicit Method for Pressure Linked Equations] algorithm and uses the second-order upwind style to discretize the computational domain to solve the three-dimensional, steady, incompressible turbulent flow around the high-speed train.…”

Section: Computational Grid and Numerical Methodsmentioning

confidence: 99%

Influence of Structural Types of CRTS I Plate-Type Ballastless Track on Aerodynamic Characteristics of High-Speed Train

Bian

Zhang

2022

Urban Rail Transit

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In order to improve the running quality of trains on a ballastless track, the influence of the CRTS I ballastless track with different structures (flat-type and frame-type tracks) is investigated with respect to the aerodynamic characteristics of high-speed trains. In the present paper, the aerodynamic force changes on the head, middle, tail, and whole car of the high-speed train were studied under two conditions, with crosswind and without crosswind, and the influence of different crosswind speeds (10, 15, 20, 25, 30 m/s) on the aerodynamic force of the train was analyzed. The pressure and flow field distribution characteristics were also studied, and the reasons for the different aerodynamic characteristics of different track structures and trains running in different wind environments were analyzed, respectively. The results indicate that the ballastless track structure obviously influences the aerodynamic characteristics of the high-speed train. When there is no natural wind, compared with the flat track, the frame track reduces the drag and lateral forces of the train but increases the lift force. The frame track causes the drag force of the whole vehicle to decrease slightly (the maximum ratio is 2.15%), the lift force increases significantly (the maximum ratio is 12.55%), and the lateral force obviously decreases (the maximum ratio is 52.43%). The lift and lateral forces of the middle car are most affected, which is because the frame structure changes the vortex motion state of the middle car. Compared with the flat track, the drag force of each car on the frame track is reduced under the crosswind; the lift force of each car is increased, and the maximum increase in the lift force of the head, middle, and tail cars is 5.60%, 2.55%, and 3.63%, respectively; the lateral force of the tail car increases greatly at a wind speed of 15 m/s, reaching 6.84%. Due to the existence of the frame structure, the space under the vehicle increases, resulting in a decrease in the airflow rate and an increase in local pressure, which leads to changes in the train’s aerodynamic force. Meanwhile, the train’s aerodynamic change under the crosswind is smaller than that when there is no wind.

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“…In the following, the obtained results were compared with the experimental data extracted by various cases. Li et al in 2019 [25] and 2020 [26] using CFD numerical analysis, the most of flow characteristics and aerodynamic forces on a highspeed train were investigated. Moreover, the effects of divergence schemes in common turbulence modeling on the aerodynamic characteristics thoroughly investigated.…”

Section: Literature Reviewmentioning

confidence: 99%

Investigation of Wall Function Effects on Aerodynamic Characteristics of Turbulent Flow Around a Simplified High-Speed Train

Hajipour¹,

Lavasani²,

Yazdi³

2021

IJHT

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Modelling of turbulence is a vital issue for flow forecasting which is of great interest for most of engineering applications like flow over planes, movement of pollutants and some industrial processes. Originally, via solving the government equations (Navier-Stokes equations) the flow field can be simulated. With developing PCs and high-performance computers, implementing of Navier-Stokes equations for numerical simulation is increasing. In this research, the effects of some wall functions on aerodynamic and turbulence behavior of air flow around a simplified high-speed train via OpenFOAM software are numerically investigated. In the following, first, the effects of some default and common wall functions of OpenFOAM on the flow and aerodynamic key parameters are analyzed and then, a relatively new wall function called “Enhanced Wall Function” was implemented from ANSYS FLUENT into OpenFOAM and improvement for comprehensive simulation. Variations of flow key parameters such as velocity, pressure distribution and aerodynamic significant components and parameters such as lift, drag and side coefficients under the influence of wall functions changes are illustrated. The results could be used for obtaining more accurate analysis of aerodynamic characteristics of fluid flow around high-speed trains.

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On the Reynolds-Averaged Navier-Stokes Modelling of the Flow around a Simplified Train in Crosswinds

Cited by 17 publications

References 31 publications

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

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

Influence of Structural Types of CRTS I Plate-Type Ballastless Track on Aerodynamic Characteristics of High-Speed Train

Investigation of Wall Function Effects on Aerodynamic Characteristics of Turbulent Flow Around a Simplified High-Speed Train

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