Full scale measurements on high speed train Etr 500 passing in open air and in tunnels of Italian high speed line

A broadband noise source model based on Lighthill’s acoustic theory was used to perform numerical simulations of the aerodynamic noise sources for a high-speed train. The near-field unsteady flow around a high-speed train was analysed based on a delayed detached-eddy simulation (DDES) using the finite volume method with high-order difference schemes. The far-field aerodynamic noise from a high-speed train was predicted using a computational fluid dynamics (CFD)/Ffowcs Williams-Hawkings (FW-H) acoustic analogy. An analysis of noise reduction methods based on the main noise sources was performed. An aerodynamic noise model for a full-scale high-speed train, including three coaches with six bogies, two inter-coach spacings, two windscreen wipers, and two pantographs, was established. Several low-noise design improvements for the high-speed train were identified, based primarily on the main noise sources; these improvements included the choice of the knuckle-downstream or knuckle-upstream pantograph orientation as well as different pantograph fairing structures, pantograph fairing installation positions, pantograph lifting configurations, inter-coach spacings, and bogie skirt boards. Based on the analysis, we designed a low-noise structure for a full-scale high-speed train with an average sound pressure level (SPL) 3.2 dB(A) lower than that of the original train. Thus, the noise reduction design goal was achieved. In addition, the accuracy of the aerodynamic noise calculation method was demonstrated via experimental wind tunnel tests.

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Full-Scale Measurement and Numerical Simulation of Flow Around High-Speed Train in Tunnel

Journal of Mechanical Systems for Transportation and Logistics ◽

10.1299/jmtl.1.281 ◽

2008 ◽

Vol 1 (3) ◽

pp. 281-292 ◽

Cited By ~ 12

Author(s):

Masahiro SUZUKI ◽

Atsushi IDO ◽

Yutaka SAKUMA ◽

Hiroshi KAJIYAMA

Keyword(s):

Numerical Simulation ◽

High Speed ◽

Full Scale ◽

High Speed Train

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

Proceedings of the Institution of Mechanical Engineers Part F Journal of Rail and Rapid Transit ◽

10.1177/0954409716641150 ◽

2016 ◽

Vol 231 (6) ◽

pp. 740-756 ◽

Cited By ~ 6

Author(s):

Chunli Zhu ◽

Hassan Hemida ◽

Dominic Flynn ◽

Chris Baker ◽

Xifeng Liang ◽

...

Keyword(s):

Sound Pressure Level ◽

High Speed ◽

Sound Pressure ◽

Low Frequency ◽

Pressure Level ◽

Broadband Noise ◽

Full Scale ◽

High Speed Train ◽

Noise Characteristics ◽

Simulation Results

The flow field and sound propagation around a three-coach 1/8th scale high-speed passenger train were obtained using a detached-eddy simulation and the Ffowcs-Williams and Hawkings acoustic analogy. The Reynolds number of flow based on the train height and speed was 2,000,000. The numerical results of the flow and aeroacoustic fields were validated using wind tunnel experiments and full-scale data, respectively. Features of overall sound pressure level, sound pressure level and A-weighted sound pressure level of typical measuring points are discussed. The sound propagated by a high-speed train is shown as a broadband noise spectrum including tonal component, where high sound pressure levels are concentrated on the low-frequency range from 10 Hz to 300 Hz. The inter-carriage gap is found to cause distinct tonal noise in contrast to the other parts of the train that cause a broadband noise. The negative log law has been used to study the influence of distance from the centre of track on the sound pressure level, where a good fit is shown at low-frequency ranges. The peak values of A-weighted sound pressure level from both full-scale experiment and simulation results occur at approximately 1 kHz, where simulation results show almost the same range as the experiment. The surface of each component of the train as well as the whole train are chosen as the integral surface for the Ffowcs-Williams and Hawkings computation of the far-field noise characteristics. It was found that the sound source generated by a high-speed train is mainly dipole, and the largest noise was obtained from the leading bogie. The results of this paper provide, for the first time, a better understanding of the aeroacoustic field around a three-coach train model, and the paper has the potential to assist engineers to design high-speed trains with aeroacoustic noise reduction in a better manner.

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Aerodynamic Coefficients of a High-Speed Train in Presence of Windbreaks With Different Gap Configurations

2020 Joint Rail Conference ◽

10.1115/jrc2020-8115 ◽

2020 ◽

Author(s):

Elia Brambilla ◽

Gisella Tomasini ◽

Stefano Giappino

Keyword(s):

Wind Tunnel ◽

High Speed ◽

Full Scale ◽

High Speed Train ◽

European Standard ◽

Aerodynamic Coefficients ◽

Scaled Model ◽

Wind Tunnel Tests ◽

Cfd Analyses ◽

High Band

Abstract In the present paper the force aerodynamic coefficients measured, according the European Standard Specifications, by means of wind tunnel tests carried out on a 1:15 scaled model of ETR1000 train in presence of different windbreaks configurations, are presented. In particular, 3m high band barriers (40% of porosity) have been tested with different gaps (from 0,5m to 30m, full scale) in the windbreaks and considering different positions of the train with respect to the gaps. The results shown in this paper allow to evaluate the effect of different windbreak parameters (gap amplitude, train position) on the train overturning risk and they represent a complete database for validation of CFD analyses.

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Analysis of High Speed Train Flow Structures Under Crosswind

Volume 1: Symposia ◽

10.1115/ajkfluids2015-17796 ◽

2015 ◽

Author(s):

Terence Avadiar ◽

James Bell ◽

David Burton ◽

Heman Cormaty ◽

Chao Li

Keyword(s):

Boundary Layer ◽

Wind Tunnel ◽

High Speed ◽

Streamwise Vortex ◽

Full Scale ◽

Full Length ◽

Flow Structures ◽

High Speed Train ◽

Velocity Measurements ◽

Through Flow

The flow structures along the length of a High-Speed Train (HST) under crosswind are investigated in a wind tunnel, through flow visualisations and velocity measurements at various angles of yaw. Surface visualisations show the development of a streamwise vortex originating at the nose that travels longitudinally along the length of the train. In addition, the hypothesis that flow structures repeat when the boundary layer (BL) on the roof of the HST model is pushed off is tested, with a view to analysing the effectiveness of using shortened HST models to accurately represent full-length trains in a wind tunnel. It would appear that using a shortened train model cannot completely model full-scale HSTs at realistic yaw angles using this theory.

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A comparative study of methods to simulate aerodynamic flow beneath a high-speed train

Proceedings of the Institution of Mechanical Engineers Part F Journal of Rail and Rapid Transit ◽

10.1177/0954409717734090 ◽

2017 ◽

Vol 232 (5) ◽

pp. 1464-1482 ◽

Cited By ~ 5

Author(s):

David Soper ◽

Dominic Flynn ◽

Chris Baker ◽

Adam Jackson ◽

Hassan Hemida

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Numerical Simulations ◽

High Speed ◽

Experimental Studies ◽

Model Tests ◽

Full Scale ◽

High Speed Train ◽

Computational Fluid Dynamics Simulations ◽

Dynamics Simulations

The introduction of dedicated high-speed railway lines around the world has led to issues associated with running trains at very high speeds. Aerodynamic effects proportionally increase with train speed squared; consequently, at higher speeds aerodynamic effects will be significantly greater than those of trains travelling at lower speeds. On ballasted track beds, the phenomenon in which ballast particles become airborne during the passage of a high-speed train has led to the need for understanding the processes involved in train and track interaction (both aerodynamical and geotechnical). The difficulty in making full-scale aerodynamic measurements beneath a high-speed train has created the requirement to be able to accurately simulate these complex aerodynamic flows at the model scale. In this study, the results of moving-model tests and numerical simulations were analysed to determine the performance of each method for simulating the aerodynamic flow underneath a high-speed train. Validation was provided for both cases by juxtaposing the results against those from full-scale measurements. The moving-model tests and numerical simulations were performed at the 1/25th scale. Horizontal velocities from the moving-model tests and computational fluid dynamics simulations were mostly comparable except those obtained close to the ballast. In this region, multi-hole aerodynamic probes were unable to accurately measure velocities. The numerical simulations were able to resolve the flow to much smaller turbulent scales than could be measured in the experiments and showed an overshoot in peak velocity magnitudes. Pressure and velocity magnitudes were found to be greater in the numerical simulations than in the experimental tests. This is thought to be due to the influence of ballast stones in the experimental studies allowing the flow to diffuse through them, whereas in the computational fluid dynamics simulations, the flow stagnated on a smooth non-porous surface. Additional validation of standard deviations and turbulence intensities found good agreement between the experimental data but an overshoot in the numerical simulations. Both moving model and computational fluid dynamics techniques were shown to be able to replicate the flow development beneath a high-speed train. These techniques could therefore be used as a method to model underbody flow with a view to train homologation.

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