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.

摘要

由于两个紧密相连的流线型结构，高速运行的双列机组列车可能会带来其他的空气动力学挑战，探索双列机组的空气动力学性能现在至关重要。在这项研究中，采用分离涡流模拟（DES）方法研究双单元火车的空气动力性能和附近的流型，并将其结果与相同长度的单单元火车的结果进行比较和分析。结果表明，耦合方法可以改变每辆车的空气阻力，并有可能增加双单元列车的总阻力。耦合器附近的前轿厢的提升力大大增加。在靠近耦合器的区域中，在前半单和双单元列车周围发现了类似的滑流分布。由于采用了耦合结构，因此双单元列车后半部分的滑流比单单元列车要强得多。双单元序列后面的涡流区域比单单元序列后面的涡流区域宽得多，并且伴随着更大的涡流脱落。