Numerical Study of the Aerodynamic Performance of a Train with a Crosswind for Different Embankment Heights
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Numerical Study of the Aerodynamic Performance of a Train with a Crosswind for Different Embankment Heights Xianli Li1,2,3,4 · Guang Chen1,2,3 · Siniša Krajnovic5 · Dan Zhou1,2,3 Received: 19 February 2020 / Accepted: 23 August 2020 © Springer Nature B.V. 2020
Abstract A numerical study using improved delayed detached eddy simulation (IDDES) was used to investigate the influence of the embankment height on the aerodynamic performance of a high-speed train travelling under the influence of a crosswind. The results of the flow predictions were used to explore both the instantaneous and the time-averaged flows and the resulting aerodynamic forces, moments and slipstreams. An increase of the aerodynamic drag and side forces as well as the lift force of the head and middle cars were observed with rising embankment height. While the lift force of the tail car decreased with the increasing embankment height. Furthermore, the height of the embankment was found to have a strong influence on the slipstream on the leeward side of the train. The correlation between the embankment height and the slipstream velocity on the windward side, was rather small. The flow structures in the near-wake of the leeward side of the train, responsible for the aerodynamic properties of the train were analyzed, showing strong dependency on the embankment height. Keywords IDDES · Embankment · Crosswind · Slipstream · Flow structures
* Dan Zhou [email protected] 1
Key Laboratory of Traffic Safety on Track (Central South University), Ministry of Education, Hunan 410075 Changsha, People’s Republic of China
2
Joint International Research Laboratory of Key Technology for Rail Traffic Safety, Hunan 410075 Changsha, People’s Republic of China
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School of Traffic and Transportation Engineering, Central South University, Hunan 410075 Changsha, People’s Republic of China
4
School of Civil Engineering, Central South University, Hunan 410075 Changsha, People’s Republic of China
5
Department of Mechanics and Maritime Sciences, Chalmers University of Technology, 41296 Gothenburg, Sweden
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Flow, Turbulence and Combustion
1 Introduction A train operating in the open air forms a slipstream as a result of the air displacement around the train. The turbulent flow in the region near the train sides is moving at the speed comparable to that of the train leading to safety risks for objects, people and animals close to the train. The problem with slipstream has increased with high-speed trains (HSTs) operating at speeds of 300 km/h and higher. A number of incidents caused by slipstream have been reported in UK, Switzerland, and Austria (Pope 2006; Flynn et al. 2016; Chen et al. 2019a), leading to a need for a research of the phenomena and how to prevent it. Several studies of the slipstreams of trains have been performed in the absence of crosswinds. For example, Wang et al. (2018a) compared the effects of the presence or absence of bogies on the slipstream around a train. Xia et al. (2017) compared the effects of stationary and
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