Effect of the inter-car gap length on the aerodynamic characteristics of a high-speed train

Abstract

In wind tunnel experiments, the inter-car gaps are designed in such a way as to separate the force measurements for each car and prevent the interference between cars during tests. Moreover, the inter-car gap has a significant effect on the aerodynamic drag of a train. In order to guide the design of the inter-car gaps between cars in wind tunnel experiments, the impact of the inter-car gap length on the aerodynamic characteristics of a 1/8th scale high-speed train is investigated using computational fluid dynamics. The shear stress transport k-ω model is used to simulate the flow around a high-speed train. The aerodynamic characteristics of the train with 10 different inter-car gap lengths are numerically simulated and compared. The 10 different inter-car gap lengths are 5, 8, 10, 15, 20, 30, 40, 50, 60, and 80 mm. Results indicate that the aerodynamic drag coefficients obtained using computational fluid dynamics fit the experimental data well. Rapid pressure variations appear in the upper and lower parts of the inter-car gaps. With the increase of the inter-car gap length, the drag force coefficient of the head car gradually increases. The total drag force coefficients of the trains with the inter-car gap length less than 10 mm are practically equal to those of the trains without inter-car gaps. Therefore, it can be concluded from the present study that 10 mm is recommended as the inter-car gap length for the 1/8th scale high-speed train models in wind tunnel experiments.

Keywords

Inter-car gap computational fluid dynamics aerodynamics wind tunnel experiment

Get full access to this article

View all access options for this article.

References

CEN European Standard. EN 14067-4 railway applications – aerodynamics part 4: requirements and test procedures for aerodynamics on open track. Technical report, CEN, 2009.

CEN European Standard. EN 14067-6 railway applications – aerodynamics part 6: requirements and test procedures for cross wind assessment. Technical report, CEN, 2010.

Watkins

Saunders

Kumar

. Aerodynamic drag reduction of goods trains. J Wind Eng Ind Aerodyn 1992; 40: 147–178.

Wilemsen

. High Reynolds number wind tunnel experiments on trains. J Wind Eng Ind Aerodyn 1997; 69–71: 437–447.

Kwon

Park

Lee

et al.

Wind tunnel experiments on Korean high-speed trains using various ground simulation techniques. J Wind Eng Ind Aerodyn 2001; 89: 1179–1195.

Paul

Johnson

Yates

Application of CFD to rail car and locomotive aerodynamics. In: Browand F McCallen R Ross J (eds). The aerodynamics of heavy vehicles II: trucks, buses, and trains, Berlin, Heidelberg: Springer, 2009, pp. 259–297.

Sima M, Gurr A and Orellano A. Validation of CFD for the flow under a train with 1:7 scale wind tunnel measurements. In: BBAA VI international colloquium on: bluff bodies aerodynamics & applications 2008, Milano, Italy.

Jönsson

Wagner

Loose

. Particle image velocimetry of the underfloor flow for generic high-speed train models in a water towing tank. Proc IMechE, Part F: J Rail and Rapid Transit 2012; 228: 194–209.

Quinn

Hayward

Baker

et al.

A full-scale experimental and modelling study of ballast flight under high-speed trains. Proc IMechE, Part F: J Rail and Rapid Transit 2009; 224: 61–74.

10.

Baker

Quinn

Sima

et al.

Full-scale measurement and analysis of train slipstreams and wakes. Part 1: ensemble averages. Proc IMechE, Part F: J Rail and Rapid Transit 2013; 228: 451–467.

11.

Baker

. A review of train aerodynamics Part 2 – applications. Aeronaut J 2014; 118: 345–382.

12.

Kukreja

. Aerodynamic loss in inter-car space of train and its reduction. Int J Latest Trends Eng Tech 2016; 6: 80–89.

13.

Flynn

Hemida

Baker

. On the effect of crosswinds on the slipstream of a freight train and associated effects. J Wind Eng Ind Aerodyn 2010; 156: 14–28.

14.

Diedrichs B. Aerodynamic calculation of crosswind stability of a high-speed train suing control volumes of arbitrary polyhedral shape. In: BBAA VI international colloquium on: bluff bodies aerodynamics & applications, 2008, Milano, Italy.

15.

Eichinger

Sima

Thiele

. Numerical simulation of a regional train in cross-wind. Proc IMechE, Part F: J Rail and Rapid Transit 2015; 229: 625–634.

16.

Zhang

Zhou

. Wind tunnel experiment on aerodynamic characteristic of streamline head of high speed train with different head of high speed train with different head shapes. J Cent South Univ Sci Technol 2013; 44: 2603–2608. in Chinese).

17.

Zhang

Tian

et al.

Impact of ground and wheel boundary conditions on numerical simulation of the high-speed train aerodynamic performance. J Fluid Struct 2016; 61: 249–261.

18.

Hemida

Krajnović

. Exploring flow structures around a simplified ICE2 train subjected to a 30 side wind using LES. Eng Appl Comput Fluid Mech 2009; 3: 28–41.

19.

Liu

Hemida

Liu

. Large eddy simulation of the flow around a train passing a stationary freight wagon. Proc IMechE, Part F: J Rail and Rapid Transit 2013; 228: 535–545.

20.

Asress

Svorcan

. Numerical investigation on the aerodynamic characteristics of high-speed train under turbulent crosswind. J Mod Transport 2014; 22: 225–234.

21.

Mohammad

Masoud

. Numerical calculations of aerodynamic performance for ATM train at crosswind conditions. Wind Struct 2014; 18: 529–548.

22.

Li T, Hemida H, Zhang JY, et al. Comparisons of shear stress transport and detached eddy simulations of the flow around trains. J Fluid Eng 2018; 140: 111108–12.