Aerodynamics of High-Speed Trains

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Transportation and Future Mobility".

Deadline for manuscript submissions: closed (20 December 2023) | Viewed by 7153

Special Issue Editor

Birmingham Centre for Railway Research and Education, School of Engineering, University of Birmingham, Birmingham B15 2TT, UK
Interests: CFD; crosswinds; train aerodynamics; drag reduction; air quality
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

High-speed railways have become a common trend in the development of railways in the world, and they are also high-tech-intensive industrial projects that require technical support from various basic disciplines. In the process of the promotion of high-speed trains, variety of aerodynamic phenomena have become very serious, which significantely affect the characteristics of high-speed railways in terms of speed, comfort, reliability, stability, economy, and good compatibility with the environment.

The common issues of these high-speed trains are:

  • Effect of crosswinds on train’s stability and their mitigations.
  • High aerodynamic resistance and shape optimisation.
  • Noise from different parts of train including pantograph and train cavities.
  • Pressure variations in tunnels.
  • Head pressure pulses.
  • Air quality inside trains.
  • Vibration of tail cars especially in tunnels.
  • Aerodynamic effect of high-speed trains on the infrastructures adjasent to railways.

These are some of the aerodynamic issues that must be investigated in details for the development of high-speed railways. This Special Issue on “Aerodynamics of High-Speed Trains” will collect original research articles and comprehensive reviews, which will be peer-reviewed in the Journal of Applied Sciences. Anyone who might be interested in this topic, you are very welcome to contribute.

Dr. Hassan Hemida
Guest Editor

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Keywords

  • full-scale tests
  • physical modelling
  • computational fluid dynamics
  • aerocoustics
  • crosswinds
  • drag reduction
  • pressure pluses
  • onboard air quality

Published Papers (6 papers)

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Research

29 pages, 11639 KiB  
Article
High-Speed Vehicles in Low-Pressure Tunnels—Influence of Choked Flows
Appl. Sci. 2023, 13(18), 10314; https://doi.org/10.3390/app131810314 - 14 Sep 2023
Cited by 1 | Viewed by 434
Abstract
The aerodynamics of high-speed vehicles in evacuated tunnels is studied with particular reference to the consequences of choked flow conditions at the tails of the vehicles. It is shown that this has a dominant influence on overall conditions (pressure, temperature, velocity). Together with [...] Read more.
The aerodynamics of high-speed vehicles in evacuated tunnels is studied with particular reference to the consequences of choked flow conditions at the tails of the vehicles. It is shown that this has a dominant influence on overall conditions (pressure, temperature, velocity). Together with the need for the evacuated tunnel system to be closed, the high speeds cause the aerodynamic behaviour to differ greatly from that in conventional railway tunnels. A key purpose of the paper is to assess the relative importance of a large range of parameters and, for clarity, this is completed by focussing on a single vehicle in a single tunnel that is closed at both ends. Consideration is then given to interactions between more than one vehicle and to a twin-tube tunnel configuration in which interactions occur between vehicles moving in opposite directions. The paper closes with a brief mention of system-dependent matters that need to be considered in addition to the generic parameters investigated herein. Full article
(This article belongs to the Special Issue Aerodynamics of High-Speed Trains)
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24 pages, 14820 KiB  
Article
Dynamic Response of Outer Windshield Structure in Different Schemes under Aerodynamic Load
Appl. Sci. 2023, 13(6), 3879; https://doi.org/10.3390/app13063879 - 18 Mar 2023
Cited by 1 | Viewed by 897
Abstract
With the increase in high-speed train (HST) operation speed, the light-weight design of the train body and component structure is pursued to reduce energy consumption during operation, but this seriously deteriorates the aerodynamic performance of the light-weight structure outside the train body under [...] Read more.
With the increase in high-speed train (HST) operation speed, the light-weight design of the train body and component structure is pursued to reduce energy consumption during operation, but this seriously deteriorates the aerodynamic performance of the light-weight structure outside the train body under the effect of strong unsteady airflow, and the more obvious case is the frequently occurring problem of vibration, large deformation, and damage to the rubber exterior windshield at the connection position of HST carriages. We investigate the fluid–structure coupling mechanism of the interaction between the rubber external windshield and aerodynamic force, and compare the dynamic characteristics of windshield structure under different design parameters. A numerical simulation of three rubber outer windshield structure parameters (sidewall distance of U-shaped capsule, sidewall thickness, sidewall inclination angle) is carried out using FSI simulation of the two-way coupling method. The aerodynamic load, airflow dynamics around the windshield, and the nonlinear vibration and deformation form of the windshield is analyzed in detail. The results show that the aerodynamic response of the HST rubber external windshield analyzed by the FSI method is in good agreement with the full-scale test results. Additionally, the stiffness of the windshield can be improved by increasing the thickness of the windshield sidewall. When the distance between the sidewall of the windshield is increased, an insufficient thickness at the top of the arc causes a large local deformation at the top of the arc of the windshield. The method established and relevant research results can provide good support for the aerodynamic stability evaluation of HST windshields. Full article
(This article belongs to the Special Issue Aerodynamics of High-Speed Trains)
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19 pages, 6589 KiB  
Article
General Analytical Method to Predict the Spatial–Temporal Distribution of Extreme Pressure in High-Speed Railway Tunnels in the Post-Train Stage
Appl. Sci. 2023, 13(3), 1350; https://doi.org/10.3390/app13031350 - 19 Jan 2023
Viewed by 1015
Abstract
Long-duration aerodynamic pressure fluctuation in high-speed railway tunnels in the post-train stage causes fatigue damage to tunnel structures and facilities. It increases the risk of accidents and requires in-depth research. This complex phenomenon is caused by the superposition of multiple pressure waves generated [...] Read more.
Long-duration aerodynamic pressure fluctuation in high-speed railway tunnels in the post-train stage causes fatigue damage to tunnel structures and facilities. It increases the risk of accidents and requires in-depth research. This complex phenomenon is caused by the superposition of multiple pressure waves generated successively when a train enters/leaves a tunnel. In this study, the spatial–temporal distribution of the pressure state (SDPS) model was developed, and general equations describing the transient pressure state distribution were given. Furthermore, a prediction method for extreme pressures in tunnels and a fast calculation program were proposed based on the SDPS model. The proposed model was verified using field measurements. Using the SDPS model, the worst conditions of pressure fluctuations in tunnels were analyzed. The results show that most of the maximum positive and negative pressures are symmetrical around the midpoint of the tunnel axis and appear alternately around it. When the train/wave velocity ratio M ≤ 0.8 and the train/tunnel length ratio ε ≤ 0.8, the dimensionless position of the maximum peak-to-peak pressure region was concentrated in the region of [0.33,0.67] in the tunnel, indicating the location of potential fatigue damage. The proposed model is helpful in building safe and sustainable transportation systems. Full article
(This article belongs to the Special Issue Aerodynamics of High-Speed Trains)
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10 pages, 3037 KiB  
Article
Evaluation of the Aerodynamic Effect of a Smooth Rounded Roof on Crosswind Stability of a Train by Wind Tunnel Tests
Appl. Sci. 2023, 13(1), 232; https://doi.org/10.3390/app13010232 - 24 Dec 2022
Cited by 2 | Viewed by 1238
Abstract
The advent of high-speed trains led to new issues and constraints for railway network manufacturers and operators. This is the case of crosswind effect, that occurs when train is running in strong wind conditions. The combination of train speed and wind speed generates [...] Read more.
The advent of high-speed trains led to new issues and constraints for railway network manufacturers and operators. This is the case of crosswind effect, that occurs when train is running in strong wind conditions. The combination of train speed and wind speed generates a relative flow that affects the train stability. Wind tunnel tests on still railway vehicles (relative wind-train velocity in coincidence with absolute wind velocity) are mandatory according to Technical Specification for Interoperability (TSI) to ensure high-speed train safety. However, issues related to the correct evaluation of the full-scale aerodynamic behaviour of the trains can arise. In the present work, aerodynamic force and pressure coefficients measured in wind tunnel tests on a scaled model of ETR1000 high-speed train on single track ballast and rails are presented. The tests were performed in the GVPM wind tunnel of Politecnico di Milano. Results show that different flow behaviours can occur at high yaw angles when the train behaves like a bluff body depending on wind speed used during the test. Full article
(This article belongs to the Special Issue Aerodynamics of High-Speed Trains)
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19 pages, 5386 KiB  
Article
A Separated-Flow Model for 2-D Viscous Flows around Bluff Bodies Using the Panel Method
Appl. Sci. 2022, 12(19), 9652; https://doi.org/10.3390/app12199652 - 26 Sep 2022
Viewed by 1350
Abstract
Panel methods have been applied to many fields of fluid owing to their computational efficiency. However, their applications are limited in simulating highly turbulent flow with separations due to the inviscid flow assumptions, such as those associated with train aerodynamics. Some researchers employed [...] Read more.
Panel methods have been applied to many fields of fluid owing to their computational efficiency. However, their applications are limited in simulating highly turbulent flow with separations due to the inviscid flow assumptions, such as those associated with train aerodynamics. Some researchers employed the wake models to simulate large vortices in the wake of trains with predetermined separation locations according to experimental results. In this paper, a modified 2-D constant source/vortex panel method for modelling the separated flow around 2-D bluff bodies is presented. The proposed separated-flow model includes the prediction of separation locations based on the integral boundary-layer method and the shear layer, and large vortices in the wake of the bluff bodies are modelled by the wake model. The proposed method is validated by comparing the calculated pressure distribution on a 2-D circular cylinder with the experimental results. The method is then applied to simulate the flow around a 2-D generic train and calculate the pressure distribution on the train. Since trains run very close to the ground, the effect of the ground configuration on the pressure distribution of the 2-D train is also investigated in this paper using the proposed method. The main contribution of the work is to present a 2-D separated-flow model with wake modelling and separation prediction. The proposed model can be used in the rapid evaluation of bluff-body aerodynamics. Full article
(This article belongs to the Special Issue Aerodynamics of High-Speed Trains)
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16 pages, 7710 KiB  
Article
Unsteady Aerodynamic Characteristics of a High-Speed Train Induced by the Sudden Change of Windbreak Wall Structure: A Case Study of the Xinjiang Railway
Appl. Sci. 2022, 12(14), 7217; https://doi.org/10.3390/app12147217 - 18 Jul 2022
Cited by 9 | Viewed by 1378
Abstract
Under strong winds, the effect of sudden windbreak transition (WT) on high-speed trains is severe, leading to a deterioration of train aerodynamics and sudden yawing motion of the car body. To address these problems, based on a high-speed train and the specific geometric [...] Read more.
Under strong winds, the effect of sudden windbreak transition (WT) on high-speed trains is severe, leading to a deterioration of train aerodynamics and sudden yawing motion of the car body. To address these problems, based on a high-speed train and the specific geometric conditions derived from Xinjiang railway, first, the impact of a WT on the train and reasons for sudden changes in aerodynamic forces were determined by flow structural analysis. Furthermore, based on a multibody system dynamic model, the dynamic responses to WT were analysed. The results show that the impacts of WT were the strongest on the head car. WT had a strong effect on the train due to the unreasonable structural shape and the insufficient height of the windbreak in the transition region. This led to a strong push effect on the train; subsequently, the train’s dynamic characteristics deteriorated. Full article
(This article belongs to the Special Issue Aerodynamics of High-Speed Trains)
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