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Research Papers: Flows in Complex Systems

Aerodynamic Effects of Unvented Hoods on the Initial Compression Wave Generated by a High-Speed Train Entering a Tunnel

[+] Author and Article Information
Xintao Xiang

Department of Engineering Mechanics,
MOE Key Laboratory of Hydrodynamics,
Shanghai Jiao Tong University,
Shanghai 200240, China
e-mail: xtxiang@sjtu.edu.cn

Leiping Xue

Department of Engineering Mechanics,
MOE Key Laboratory of Hydrodynamics,
Shanghai Jiao Tong University,
Shanghai 200240, China
e-mail: lpxue@sjtu.edu.cn

Benlong Wang

Department of Engineering Mechanics,
MOE Key Laboratory of Hydrodynamics,
Shanghai Jiao Tong University,
Shanghai 200240, China
e-mail: benlongwang@sjtu.edu.cn

1Corresponding author.

Contributed by the Fluids Engineering Division of ASME for publication in the JOURNAL OF FLUIDS ENGINEERING. Manuscript received February 1, 2015; final manuscript received August 22, 2015; published online October 1, 2015. Assoc. Editor: Moran Wang.

J. Fluids Eng 138(3), 031102 (Oct 01, 2015) (9 pages) Paper No: FE-15-1080; doi: 10.1115/1.4031482 History: Received February 01, 2015; Revised August 22, 2015

The influence of unvented hood on the initial compression wave generated by a high-speed train entering a tunnel is investigated using computational fluid dynamics. Comparisons with experimental data are first carried out to verify the numerical model. The relationship between the pressure gradient peaks and main aspect factors is studied by parametric analysis. Influences of train speed, blockage ratio of train to tunnel, section area ratio of hood to tunnel, and hood length are investigated. Based on the numerical results, two empirical formulations are proposed to predict the influence of hood and tunnel geometries on the maximum pressure gradient during the CRH3 entering a tunnel with unvented hood.

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Figures

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Fig. 1

The compression waves generated by a normal entrance and an unvented hood. In the subfigures, the solid lines show pressures, and the dashed lines show pressure gradients.

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Fig. 2

The sketch of computational domain

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Fig. 3

The sketch of model trains and tunnel used in the reduced-scale experiments [11]. From top to bottom are ellipsoidal long-nose train, ellipsoidal short-nose train, and unvented hood.

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Fig. 4

Mesh distributions around train nose and near the tunnel entrance: long-nose train with different grid sizes

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Fig. 5

Mesh distributions around train nose and inside the hood: short-nose train with multiblock grids

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Fig. 8

CRH3 nose and distribution of cross section area along the nose

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Fig. 9

Geometries and meshes of unvented hoods of single-track and double-track tunnels. The section ratios are 2.0, and the hood lengths are 20 m.

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Fig. 10

Comparison between axisymmetric assumption and realistic 3D tunnel: U=350 km/hr, κ=0.161, r = 2.0, and Lh=20 m. Open circles are results of axisymmetric tunnel and solid line is 3D single-track tunnel.

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Fig. 11

Influence of hood length on the history of pressure gradient: U=350 km/hr, κ=0.161, and r = 2.5

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Fig. 12

Influence of hood length on the maximum pressure gradient: U=350 km/hr and κ=0.161

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Fig. 13

Influence of section ratio on the history of pressure gradient: U=350 km/hr, κ=0.161, and Lh=25 m

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Fig. 14

Influence of section ratio on the maximum pressure gradient: U=350 km/hr and κ=0.161

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Fig. 15

The relationship between A1* and r: symbols are numerical results with α=1.25 and solid line is formula (11); Lh=20 m

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Fig. 6

Histories of pressure gradients for long-nose train entering at 294 km/hr : solid line is numerical result with δt*=0.017 and δL*=0.05 and symbols o are experimental data by Howe et al. [11]

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Fig. 7

Histories of pressure gradients for short-nose train entering at 345 km/hr : solid line is numerical result with δt*=0.01 and multiblock grids and symbols o are experimental data by Howe et al. [11]

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Fig. 16

The relationship between A2* and r: symbols are numerical results with β1=3.3, β2=0.45 and dashed line is formula (12); Lh=20 m

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Fig. 17

Comparison of peak values A1* and A2* for single- and double-track tunnels. Symbols are numerical results, solid line is formula (11) with α=1.25, and dashed line is formula (12) with β1=3.3, β2=0.45. Lh=20 m, U=350 km/hr.

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Fig. 18

Comparison of peak values A1* and A2* between single- and double-track tunnels. Symbols are numerical results, solid line is formula (11) with α=1.25, and dashed line is formula (12) with β1=3.3, β2=0.45. Lh=20 m, U=300 km/hr.

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Fig. 19

Comparison between CRH3 (open circles) and TGV (solid circles) [17]; evolutions of optimal section ratio versus M

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Fig. 20

Comparison between CRH3 (open circles) and TGV (solid circles) [17]; reduction rate on the maximum pressure gradient of optimal hood versus M

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Fig. 21

The numerical case with or without NRBC, the train nose is defined by the curve: R(x)=Rn(x/Ln)(2−x/Ln)

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Fig. 22

The compression waves generated by the numerical cases with and without NRBC, N1: Lt=90 m with NRBC at both I and II and N2: Lt=200 m with NRBC at II but without NRBC at I

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Fig. 23

The pressure gradients generated by the numerical cases with and without NRBC, N1: Lt=90 m with NRBC at both I and II; N2: Lt=200 m with NRBC at II but without NRBC at I; N3: Lt=90 m with NRBC at I but without NRBC at II; and N4: Lt=200 m with NRBC at I but without NRBC at II

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