Numerical simulation of the aerodynamic characteristics of double unit train

Abstract

Double unit trains running at high speeds may create additional aerodynamic challenges due to two streamlined structures with close proximity, exploring the aerodynamic performance of double unit trains is now critical. In this study, detached eddy simulation (DES) approach was employed to study the aerodynamic performance and the nearby flow patterns of a double unit train, whose results were compared and analyzed with that of a single-unit train with a same length. The results showed that the coupling method could change the aerodynamic drag on each car and tended to increase the overall drag of the double unit train. The lift force of the front car near the coupler was significantly increased. Similar slipstream distributions were found around the front half single and double-unit train except in a region close to the coupler. Due to the coupling structure, the slipstream of the rear half of double unit train was much stronger compared to single unit train. The vortex region behind the double-unit train was much wider than that of the single-unit train and was accompanied by greater vortex-shedding.

Numerical investigation on the aerodynamic resistances of double-unit trains with different gap lengths

“…The proposal of the DUT improves the passenger transportation efficiency. However, the presence of the double-unit region will increase aerodynamic resistance (Guo et al, 2020;Niu et al, 2017). When the running speed of a high-speed train increases, the change in aerodynamic force is more drastic.…”

“…When the running speed of a high-speed train increases, the change in aerodynamic force is more drastic. This will not only lead CONTACT Tian Li litian2008@home.swjtu.edu.cn to more energy consumption, but also raise a series of safety concerns, such as derailment and rollover (Guo et al, 2020;Hyeokbin, 2017;Yao et al, 2015). Meanwhile, Baker's research shows that maximum gusts could occur around the double-unit region, which may have an impact on the safety of the high-speed train operation (Baker et al, 2013).…”

“…Zhang et al (2017) and Sun et al (2010)obtained excellent head shapes using multi-objective aerodynamic optimization design methods and computational fluid dynamic (CFD) simulations. For DUTs, the shape is significantly changed in the double-unit region, which makes the flow more complicated (Guo et al, 2020;Niu et al, 2017), and the double-unit region will seriously increase the resistance. It may not be enough to reduce the resistance only by optimizing the head shape.…”

Influence of height of earth embankment type windbreak wall on flow field characteristics and catenary wind-induced displacement

“…The detached eddy simulation (DES) approach, which combines the advantages of the RANS model and large eddy simulation (LES) model, can smoothly switch between the area Reynolds-Averaged equations performed and the area of LES equations solved. The efficiency and accuracy of the DES method at high Reynolds numbers in massively separated flows are adequate, and the DES method is now widely considered to be a promising method for simulating the aerodynamic characteristics of high-speed trains (Chen et al, 2018(Chen et al, , 2018Guo et al, 2020). However, the DES calculation method also has certain shortcomings.…”

General Analytical Method to Predict the Spatial–Temporal Distribution of Extreme Pressure in High-Speed Railway Tunnels in the Post-Train Stage

“…The research methods for investigating pressure waves in tunnels include field measurements [8,14,18,20], moving model tests [13,21,22], numerical simulations [4,23], and theoretical analysis [24][25][26]. However, field measurements and moving model tests are usually expensive and limited by the existing test conditions, and numerical simulations with three-dimensional models consume a lot of computing resources and time [23,[27][28][29]. Additionally, the above methods are all difficult when trying to meet the needs of rapid decision-making with the lowest resource consumption, especially in engineering design.…”