Flow structure around trains under side wind conditions: a numerical study

Khier, Walid; Breuer, M.; Durst, F.

doi:10.1016/s0045-7930(99)00008-0

Cited by 126 publications

(67 citation statements)

References 7 publications

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“…Vortex C emerges from the upper leeward edge of the leading nose, and is closer to the train body than vortex A. Vortex B is generated from the train bottom and grows steadily along the train under vortex C. Vortices B and C are always close to the train. This phenomenon has been observed in the studies of Khier, Breuer, and Durst (2000), Hemida and Krajnović (2010), and García et al (2015). The S1 in the different cases is a cross-section, which is a distance of 4.22 H from the nose of the train tail, as shown in Figure 1.…”

Section: Influence Of Train Length and Wind Break Wall On Flow Field supporting

confidence: 58%

“…Flow separation occurs Figure 11. Flow structure around train: (a) schematic view of flow structures around train for small and moderate yaw angles (Khier et al, 2000) and (b) mean velocity contour of S1 (see Figure 1) variation with train length. most often on the upper surface of the streamlined head and tail cars and the cowcatcher of the head car.…”

Section: Influence Of Train Length and Wind Break Wall On Flow Field mentioning

confidence: 99%

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Numerical investigation of the aerodynamic characteristics of high-speed trains of different lengths under crosswind with or without windbreaks

Niu

Zhou

Liang

2017

Engineering Applications of Computational Fluid Mechanics

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The focus of this study was the influence of the length of a train on its aerodynamic performance, with and without wind break walls, under a crosswind. The improvement in the train's aerodynamic performance due to a wind break wall was also analyzed. Aerodynamic coefficients such as the drag force and lateral force were obtained for trains of different lengths using a numerical simulation. A delayed detached eddy simulation based on the shear-stress transport κ-ω turbulent model was used in Fluent 14.0 to simulate the unsteady aerodynamic performances of trains of different lengths under a crosswind. Through a comparison and analysis of the simulation results, the effects of the train length on the forces, pressure, and flow structure around the train were studied, along with the influence of a wind break wall on trains of different lengths. The results showed that the effects on the forces, pressure, and flow structure were focused in the region around the train tail. Furthermore, it was found that a wind break wall could improve the aerodynamic characteristics of a train under a crosswind, but amplified the influence of the train length on the aerodynamic performance of the train tail. These research results provide useful guidance for train operations under a crosswind. ARTICLE HISTORY

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Section: Influence Of Train Length and Wind Break Wall On Flow Field supporting

confidence: 58%

Section: Influence Of Train Length and Wind Break Wall On Flow Field mentioning

confidence: 99%

Numerical investigation of the aerodynamic characteristics of high-speed trains of different lengths under crosswind with or without windbreaks

Niu

Zhou

Liang

2017

Engineering Applications of Computational Fluid Mechanics

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“…The middle section fo the train remains unchanged, and basic characteristics of the flow field structure of the train are not changed by the abbreviated model [4] . 3 trains are combined as one group, that is, the head train + trailing train + tail train.…”

Section: A the Calculation Model And Conditionsmentioning

confidence: 99%

Research on Motion Stability of High-Speed Trains under Cross-Wind Effect

Yang¹,

Wang²,

Zhao³

et al. 2017

Proceedings of the 2017 International Conference on Advanced Materials Science and Civil Engineering (AMSCE 2017)

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Abstract-By taking real domestic CRH high-speed trains as research object, using the Computational Fluid Dynamics software Starccm+ to carry out numerical simulation calculations when the train runs in different vehicle speeds and cross-wind speeds, We get aerodynamic loads in diverse working conditions. Furthermore, these loads are introduced into the Dynamics Simulation Software SIMPACK, which calculates some running stability parameters such as the derailment coefficient and the reduction rate of wheel load in different cross-wind and vehicle speeds. The calculation indicates that the higher the wind speed is, the lower the vehicle's maximum operating speed is and vice versa.; the maximum safe operating speed varies with different safety index limits, which can offer reference for the control of the train's running safety under cross winds. (Abstract)

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“…Experimental studies have been undertaken, for instance, by Hemida & Baker [3,4] and by Haff et al [5]. Numerical studies with RANS based models have been reported by Diedrichs [6] and Khier et al [7]. Hemida & Krajnovic [8,9] used the large eddy simulation (LES) approach to study the influence of varying yaw angle and nose shape on flow structures around a simplified train model without inter-cap gaps and wheel bogies.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Industrial and Scientific CFD Approaches for predicting Cross Wind Stability of the NGT2 Model Train Geometry

Fragner¹,

Weinman²,

Deiterding³

et al. 2015

Int J Railw Tech

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Safety assessments of cross-wind influence on high-speed train operation require a detailed investigation of the aerodynamic forces acting on a vehicle. European norm 14067-6 permits the derivation of required integral force and moment coefficients by experiments as well as by numerical simulation. Utilizing the DLR's Next Generation Train 2 model geometry, we have performed a case study comparing simulations with varying turbulence modeling assumptions. Because of its relevance for actual design, a focus lies on steady RANS computations, but more expensive unsteady RANS (URANS) and delayed detached eddy simulations (DDES) have also been carried out for comparison. Validation data for the exact same model configuration and moderate Reynolds numbers 250,000 and 450,000 is provided by side wind tunnel experiments. Particular emphasis is laid on simulating a yaw angle of 30• , for which a major vortex system on the leeward side of the train leads to sizeable uncertainties in predicted integral coefficients. At small to intermediate wind angles the flow remains attached and absolute errors in integral quantities decline with decreasing yaw angles. However, a consistent relative difference to the experimental results greater than 10% raises doubts about the general reliability of CFD methods, that are not capable of capturing laminar-turbulent transition, which is observed for scaled models in industry type wind tunnel experiments.1

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Flow structure around trains under side wind conditions: a numerical study

Cited by 126 publications

References 7 publications

Numerical investigation of the aerodynamic characteristics of high-speed trains of different lengths under crosswind with or without windbreaks

Numerical investigation of the aerodynamic characteristics of high-speed trains of different lengths under crosswind with or without windbreaks

Research on Motion Stability of High-Speed Trains under Cross-Wind Effect

Comparison of Industrial and Scientific CFD Approaches for predicting Cross Wind Stability of the NGT2 Model Train Geometry

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