Numerical simulation of the slipstream and aeroacoustic field around a high-speed train

Zhu, Chunli; Hemida, Hassan; Flynn, Damian; Baker, C.J.; Liang, Xifeng; Zhou, Dan

doi:10.1177/0954409716641150

Cited by 23 publications

(7 citation statements)

References 57 publications

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“…Figure 4 presents the two computational domains used to model the flow field around the EMU320 in the open field and the tunnel, respectively, with applied boundary conditions and related dimensions. The blockage ratio of the computation domain for the open-field case is 0.81%, which is much less than the typically accepted range of 5% according to CEN (European Committee for Standardization) [22]. The cross-sectional shape of the tunnel is determined by using the existing tunnel with a radius and area of 6.519 m and 98.81 m 2 , respectively.…”

Section: Target Model and Details On Simulationmentioning

confidence: 93%

Comparative Analysis of Surface Pressure Fluctuations of High-Speed Train Running in Open-Field and Tunnel Using LES and Wavenumber-Frequency Analysis

Lee

Cheong

Kim³

et al. 2021

Applied Sciences

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The interior noise of a high-speed train due to the external flow disturbance is more than ever a major problem for product developers to consider during a design state. Since the external surface pressure field induces wall panel vibration of a high-speed train, which in turn generates the interior sound, the first step for low interior noise design is to characterize the surface pressure fluctuations due to external disturbance. In this study, the external flow field of a high-speed train cruising at a speed of 300 km/h in open-field and tunnel are numerically investigated using high-resolution compressible LES (large eddy simulation) techniques, with a focus on characterizing fluctuating surface pressure field according to surrounding conditions of the cruising train, i.e., open-field and tunnel. First, compressible LES schemes with high-resolution grids were employed to accurately predict the exterior flow and acoustic fields around a high-speed train simultaneously. Then, the predicted fluctuating pressure field on the wall panel surface of a train was decomposed into incompressible and compressible ones using the wavenumber-frequency transform, given that the incompressible pressure wave induced by the turbulent eddies within the boundary layer is transported approximately at the mean flow and the compressible pressure wave propagated at the vector sum of the sound speed and the mean flow velocity. Lastly, the power levels due to each pressure field were computed and compared between open-field and tunnel. It was found that there is no significant difference in the power levels of incompressible surface pressure fluctuations between the two cases. However, the decomposed compressible one in the tunnel case is higher by about 2~10 dB than in the open-field case. This result reveals that the increased interior sound of the high-speed train running in a tunnel is due to the compressible surface pressure field.

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Section: Target Model and Details On Simulationmentioning

confidence: 93%

Comparative Analysis of Surface Pressure Fluctuations of High-Speed Train Running in Open-Field and Tunnel Using LES and Wavenumber-Frequency Analysis

Lee

Cheong

Kim³

et al. 2021

Applied Sciences

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“…The quadrupole term is neglected in this study because its contribution can be considered negligible for low Mach number flow. 17–29 Several authors 26–29 successfully validated numerical calculation without including the volume term compared with experimental data at low Mach numbers. This allows the integration surfaces to be selected as the solid surfaces which has significant advantages is limiting the mesh size and avoiding pseudo noise.…”

Section: Methodsmentioning

confidence: 99%

Effect of different typical high speed train pantograph recess configurations on aerodynamic noise

Kim

Thompson

2020

Proceedings of the Institution of Mechanical Engineers, Part F:

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For high-speed trains, the aerodynamic noise becomes an essential consideration in the train design. The pantograph and pantograph recess are recognised as important sources of aerodynamic noise. This paper studies the flow characteristics and noise contributions of three typical high-speed train roof configurations, namely a cavity, a ramped cavity and a flat roof with side insulation plates. The Improved Delayed Detached-Eddy Simulation approach is used for the flow calculations and the Ffowcs Williams & Hawkings aeroacoustic analogy is used for far-field acoustic predictions. Simulations are presented for a simplified train body at 1/10 scale and 300 km/h with these three roof configurations. In each case, two simplified pantographs (one retracted and one raised) are located on the roof. Analysis of the flow fields obtained from numerical simulations clearly shows the influence of the train roof configuration on the flow behaviour, including flow separations, reattachment and vortex shedding, which are potential noise sources. A highly unsteady flow occurs downstream when the train roof has a cavity or ramped cavity due to flow separation at the cavity trailing edge, while vortical flow is generated by the side insulation plates. For the ramped cavity configuration, moderately large pressure fluctuations appear on the cavity outside walls in the upstream region due to unsteady flow from the upstream edge of the plate. The raised pantograph, roof cavity, and ramped cavity are identified as the dominant noise sources. When the retracted pantograph is located in the ramped roof cavity, its noise contribution is less important. Furthermore, the insulation plates also generate tonal components in the noise spectra. Of the three configurations considered, the roof cavity configuration radiates the least noise at the side receiver in terms of A-weighted level.

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“…DES (detached eddy simulation) is a representative hybrid RANS-LES method that was originally proposed by Spalart et al (1997). With fast development in turbulence model, the DES is becoming a promising method in modelling separated flows at high Reynolds numbers, showing a good prediction in the external flow around ground transport vehicles (Favre and Efraimsson, 2011;Guilmineau et al, 2013;Flynn et al, 2014;Morden et al, 2015;Huang et al, 2016;Niu et al, 2017;Zhu et al, 2017;Zhang et al, 2016Zhang et al, , 2017Zhang et al, and 2018a.…”

Section: Methodsmentioning

confidence: 99%

Effect of Two Bogie Cavity Configurations on the Underbody Flow and Near Wake Structures of a High-Speed Train

Zhang

et al. 2019

JAFM

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A time-dependent simulation method, DES (detached eddy simulation), combined with Realizable k-ε turbulence model, has been adopted to study the underbody flow and near wake structures of a high-speed train with two bogie cavity configurations laid on the stationary ground. The numerical data, including timeaveraged aerodynamic drag forces and pressure coefficients, were compared with experimental results from previous wind tunnel tests. A detail comparison of the instantaneous flow structures, mean velocity vector contours, velocity and pressure profiles under the train bottom in the symmetry plane and velocity contours overlaid with streamlines in the wake has been conducted in the two configurations. Also the aerodynamic drag coefficients for the two cases are discussed herein. The two cases show that the bogie cavity configurations contribute to the differences of velocity and pressure distributions in each bogie region, as well as the complex vortex structures around the bogie regions. Compared to the inclined bogie cavity configuration, the train with straight plates experiences a lower drag force by 2.8% for a three-car model in the stationary ground. Thus, an effective simplification criterion for the train model will contribute to an accurate prediction of forces of trains in simulations.

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Numerical simulation of the slipstream and aeroacoustic field around a high-speed train

Cited by 23 publications

References 57 publications

Comparative Analysis of Surface Pressure Fluctuations of High-Speed Train Running in Open-Field and Tunnel Using LES and Wavenumber-Frequency Analysis

Comparative Analysis of Surface Pressure Fluctuations of High-Speed Train Running in Open-Field and Tunnel Using LES and Wavenumber-Frequency Analysis

Effect of different typical high speed train pantograph recess configurations on aerodynamic noise

Effect of Two Bogie Cavity Configurations on the Underbody Flow and Near Wake Structures of a High-Speed Train

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