Numerical simulation of rainwater accumulation and flow characteristics over windshield of high-speed trains

Du, Jian; Liang, Xifeng; Li, Guibo; Tian, Honglei; Yang, Mingzhi

doi:10.1007/s11771-020-4288-z

Cited by 13 publications

(4 citation statements)

References 14 publications

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“…The VOF method is suitable for solving the free surface tracking description problem for two or more immiscible fluids, wherein only one fluid (e.g., air) is compressible [38][39][40]. The method has been validated and is widely used in wave simulations [41][42][43][44][45], dam-break models [38,46], and multiform step-fall simulations [47][48][49].…”

Section: Volume Of Fluid (Vof) Methodsmentioning

confidence: 99%

Flow Pattern and Escape Hazards of People from Flood Intrusion into the Staircase of Underground Spaces with Multiple Rest Platforms

Lin,

Hu,

Lin

2024

Buildings

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While urban underground space is being built and developed at a high speed, urban flooding is also occurring gradually and frequently. Urban water, in many disasters, has intruded into underground spaces, such as subway stations, often leading to serious casualties, in which it is crucial for people to be able to escape from the staircases. In order to enable and guide the escape of people in underground floods, a staircase model with multiple rest platforms, applicable to common entrance and exit staircase forms, was constructed. The realizable k-ε turbulence model, coupled with a volume of fluid (VOF) method, was used to simulate and analyze the flow patterns when floods of various heights intrude into the structure. The effects of rest platform settings on the ejection phenomena and flow velocity changes in flood flows were summarized. The change rule of flood flow velocity on the stairs under different flood heights and stair heights was summarized, and a linear relationship between the peak flood flow velocity and the location of the peak flow velocity point on each flight of stairs was derived. Combined with the formula of the critical conditions for people to escape upwards in the flood, the proposed escape conditions for staircases with multiple rest platforms were proposed, which provide a basis for guiding the evacuation of people in times of disaster.

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Section: Volume Of Fluid (Vof) Methodsmentioning

confidence: 99%

Flow Pattern and Escape Hazards of People from Flood Intrusion into the Staircase of Underground Spaces with Multiple Rest Platforms

Lin,

Hu,

Lin

2024

Buildings

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“…To avoid the simulated stress depletion (MSD) [35] and eliminate the "log layer mismatch" problem [36] caused by DDES calculation in the boundary layer, IDDES method was proposed, and the above problems have been proved in some results of previous studies [37][38][39][40] . In recent years, IDDES has been widely used in the simulation of vehicle aerodynamics [41][42][43][44][45][46][47][48] . Therefore, IDDES method based on SST k-w is used to simulate the unsteady ow eld around the plate braking train under crosswind.…”

Section: Calculation Methodsmentioning

confidence: 99%

Unsteady aerodynamic characteristics and dynamic performance of high-speed trains during plate braking under crosswind

Liu

Zheng

et al. 2023

Nonlinear Dyn

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As one of the key technologies of the train, the braking system plays a vital role in ensuring the safe operation of the train. Plate braking has the characteristics that the higher the train speed, the better the braking effect, and it can be used as one of the options for emergency braking of the high-speed train.The dynamic grid technology is used to realize the plate movement, and the unsteady aerodynamic characteristic simulation of the train in plate braking process is realized based on the IDDES with SST k-w turbulence model. The formation and evolution of the ow eld in the process of plate braking are analyzed by the visualization technology, and the in uence law of plate opening on the aerodynamic forces of each car under the crosswind is explored. By loading the aerodynamic forces into the vehicle system dynamics model for calculation, the safety indexes (derailment coe cient and wheel load reduction rate) of the plate braking train under crosswind with different speeds are obtained. The results show that the rapid opening of the plate provides a large braking force for the train, but it destroys the stability of the ow eld around the train, especially the ow eld above the train, and the above phenomenon further aggravated by crosswind. The aerodynamic force distribution of each car in the train was signi cantly changed by crosswind, the proportion of the lateral force of the head car in the train is signi cantly increased, and the aerodynamic forces of each car were further increased by the opening of the plate. From the perspective of vehicle dynamics performance, with the increase of crosswind speed, the derailment coe cient and wheel load reduction rate of each car increase obviously, and even derailment and overturn occur. Under the crosswind, the dynamic performance of the head car is the worst, and it was further deteriorated by opening of the plate. The impact of the tail car is relatively small, and the dynamic performance of the head car can be used to evaluate the safety of the train. It is recommended to avoid opening the plate of the head car in strong crosswind.

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“…Niu et al (2019) investigated the impact of the external windshield configuration on the train aerodynamic characteristics using six different configurations, employing experiments and numerical simulations. They demonstrated that a completely covered external windshield increases the head car's drag, whereas the total train drag is reduced (Du et al 2020).…”

Section: Introductionmentioning

confidence: 99%

An Investigation of Influence of Windshield Configuration and Train Length on High-Speed Train Aerodynamic Performance

Adamu

Zhang²,

Gidado³

et al. 2023

JAFM

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The aerodynamic performance of four train models with different windshield configurations (i.e., internal and/or external) in three train marshalling modes (i.e., 3, 6 and 8-car groups) was numerically investigated in this study. The train's airflow characteristics at Re=2.25×106 were determined using the shear stress transport (SST) k- turbulence model. The results were validated by comparing the pressure distributions and drag forces on the streamlined heads with experimental data. The difference in windshield configuration and train length has a substantial influence on the train’s flow field and surface pressure distribution. For the trains with internal windshields, due to non-uniform geometry, the flow is separated and vortices are formed at the windshield area. The boundary layer profile increases with the increased train length, and its thickness varies with windshield configurations. Asymmetric vortices are formed in the wake at a distance close to the tail car’s nose, except for trains with external windshields. The reduction of the flow velocity as the train length increases causes a reduction of the low pressure near the tail car’s streamline transition, thus causing a decrease in the tail car’s drag and lift forces. Consequently, for trains with external windshields, the head car’s drag increases, whereas the total train drag reduces significantly as the train length increases. Therefore, employing external windshields in all the inter-carriage gap sections, irrespective of the train length, demonstrates a good ability to reduce future train’s aerodynamic drag.

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Numerical simulation of rainwater accumulation and flow characteristics over windshield of high-speed trains

Cited by 13 publications

References 14 publications

Flow Pattern and Escape Hazards of People from Flood Intrusion into the Staircase of Underground Spaces with Multiple Rest Platforms

Flow Pattern and Escape Hazards of People from Flood Intrusion into the Staircase of Underground Spaces with Multiple Rest Platforms

Unsteady aerodynamic characteristics and dynamic performance of high-speed trains during plate braking under crosswind

An Investigation of Influence of Windshield Configuration and Train Length on High-Speed Train Aerodynamic Performance

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