Study on the effect of dimple position on drag reduction of high-speed maglev train

Zhou, Dan; Wu, Liliang; Tan, Changda; Hu, Tianen

doi:10.1093/tse/tdab027

Cited by 20 publications

(6 citation statements)

References 31 publications

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“…Therefore, the aerodynamic drag force can be effectively decreased when the inter-carriage gaps are covered with an external windshield. 12,13,28 The C p distribution along the top symmetry centreline of the head and tail cars is compared with the data of the numerical simulation from Dong et al 29 and experiment, 30 as highlighted in Figure 7. Except for the regions near the wiper and downstream the air condition on the tail car, which are depicted by the dotted box and have been smoothed in this study, the numerical simulations agreed well with the experimental results.…”

Section: Validation Of Numerical Methodsmentioning

confidence: 99%

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A numerical investigation of inter-carriage gap configurations on the aerodynamic performance of a wind-tunnel train model

Zhang

Adamu

Han

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part F:

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The influence of different inter-carriage gap configurations, including end wall geometries (3 cases) and gap spacings (0, 5, 8, 10, 15, 20, and 30 mm), on the aerodynamic characteristics of a wind-tunnel train was investigated. The shear stress transport (SST) k- ω turbulence model was employed to determine the airflow features of the train at Re = 2.25 × 106. For validation, the numerical drag force and pressure distributions on the streamlined heads were compared with the experimental benchmark of wind tunnel experiment. The numerical data show that substantial variations in the flow fields, pressure distributions and aerodynamic forces are observed between the trains with and without gap spacings, no matter which configuration is employed. As the gap spacing increases, the airflow along train body rushes into the gap easily, causing the formation of vortices at the gap between the internal and external windshields. The decreasing restriction of flow in the gap also contributes to the pressure differences on the end walls. With the increase of gap spacings, the pressure on both of the first and second inter-carriage gaps is decreased, and it on the first one is a little higher than that on the second at each gap spacing. The end wall geometry affects the flow structures around the train, especially in the region below half-height of the train. This results in a difference in the boundary layer thicknesses and drag contribution in all cases. The discrepancy of end wall geometry causes a substantial variation in the aerodynamic drag between different cases. As gap spacing increases, the aerodynamic drag of the head car decreases, while those of the middle and rear cars increase significantly. When the three cases are compared, the discrepancy of the total aerodynamic drag of Case 1 is the smallest when compared to the base case with a minimum of 0.03% at 10 mm gap spacing and followed by 0.05% at 8 mm. Therefore, to determine the aerodynamic forces for high-speed trains with fully enclosed inter-carriage configuration in wind tunnel test, having a high comparative value as the actual trains, the end wall geometry in Case 1 is recommended with a gap spacing of 10 mm or 8 mm.

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Section: Validation Of Numerical Methodsmentioning

confidence: 99%

“…Therefore, the aerodynamic drag force can be effectively decreased when the inter-carriage gaps are covered with an external windshield. 12,13,28…”

Section: Numerical Validationmentioning

confidence: 99%

A numerical investigation of inter-carriage gap configurations on the aerodynamic performance of a wind-tunnel train model

Zhang

Adamu

Han

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part F:

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“…When the train operates in a windless environment, a pair of symmetrical wake structures are generated at the rear of the tail car that are essentially identical in scale and intensity [48,49]. However, the wake structures are asymmetric and inconsistent in scale and intensity when the train runs under crosswinds.…”

Section: Flow Structure Analysismentioning

confidence: 99%

Aerodynamic Features of High-Speed Maglev Trains with Different Marshaling Lengths Running on a Viaduct under Crosswinds

Huang,

Zhou,

Chang

et al. 2024

CMES

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The safety and stability of high-speed maglev trains traveling on viaducts in crosswinds critically depend on their aerodynamic characteristics. Therefore, this paper uses an improved delayed detached eddy simulation (IDDES) method to investigate the aerodynamic features of high-speed maglev trains with different marshaling lengths under crosswinds. The effects of marshaling lengths (varying from 3-car to 8-car groups) on the train's aerodynamic performance, surface pressure, and the flow field surrounding the train were investigated using the three-dimensional unsteady compressible Navier-Stokes (N-S) equations. The results showed that the marshaling lengths had minimal influence on the aerodynamic performance of the head and middle cars. Conversely, the marshaling lengths are negatively correlated with the time-average side force coefficient (C S ) and time-average lift force coefficient (C l ) of the tail car. Compared to the tail car of the 3-car groups, the C S and C l fell by 27.77% and 18.29%, respectively, for the tail car of the 8-car groups. It is essential to pay more attention to the operational safety of the head car, as it exhibits the highest time average C S . Additionally, the mean pressure difference between the two sides of the tail car body increased with the marshaling lengths, and the side force direction on the tail car was opposite to that of the head and middle cars. Furthermore, the turbulent kinetic energy of the wake structure on the windward side quickly decreased as marshaling lengths increased.

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“…The continuous rise in HST operational speed has caused concerns about the train's aerodynamic performance, especially the aerodynamic drag related to energy consumption. The aerodynamic drag is the resistance force felt by the train as it moves in open air Zhou et al 2021;Sun et al 2020;Tan et al 2022), and increases as the train speed increases (Baker 2014;Tian 2007). Thus, for researchers, optimizing the train shape to achieve drag reduction has become a crucial issue.…”

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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Study on the effect of dimple position on drag reduction of high-speed maglev train

Cited by 20 publications

References 31 publications

A numerical investigation of inter-carriage gap configurations on the aerodynamic performance of a wind-tunnel train model

A numerical investigation of inter-carriage gap configurations on the aerodynamic performance of a wind-tunnel train model

Aerodynamic Features of High-Speed Maglev Trains with Different Marshaling Lengths Running on a Viaduct under Crosswinds

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

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