尾部仿生涡流发生器对高速列车明线气动特性影响研究

Effects of tail biomimetic vortex generators on the aerodynamic performance of high-speed train in open air

中文关键词: 高速列车  涡流发生器  仿生设计  气动力  尾部流场

英文关键词: high-speed train  vortex generator  bionic design  aerodynamic force  wake flow field

中文摘要:

      为降低高速列车在运行过程中尾部车辆所受到的气动升力和阻力,提高列车运行稳定性和节能水平,采用仿生学原理,分别以飞鱼胸鳍、游隼双翼及旗鱼背鳍为形态仿生对象,提出了三种不同形状的尾部涡流发生器设计方案。采用基于SST k-ω两方程湍流模型的IDDES方法,在确定计算区域、网格划分、定义边界条件等环节的基础上,对安装不同形状涡流发生器的高速列车分别进行了气动升力和阻力的数值模拟计算,并从尾车鼻部表面压力、尾部速度场和三维涡旋结构等角度,探讨了涡流发生器对列车尾部流场的影响机理。研究结果表明：当列车运行速度在200km/h-400km/h区间时,与原型车相比,模型Ⅰ-Ⅲ的尾车升力均得到了较大幅度的降低,平均降低率分别为38.5%、40.4%和51.3%；整车气动阻力小幅降低,平均减阻率分别为2.1%、2.4%和3.1%。涡流发生器使流经尾车鼻部的气流受到阻碍,导致此区域的正压范围和数值均发生了变化,此种变化是尾车气动升力和阻力得到降低的根本原因。通过分析列车尾部速度场和尾涡的主要特征,说明涡流发生器可以明显改善列车尾部流场的结构,并有效降低了尾涡强度。综合性能评价方面,模型Ⅲ(旗鱼)优于模型Ⅱ(游隼),模型Ⅱ优于模型Ⅰ(飞鱼)。研究内容可为降低列车尾部气动升力,保障列车安全运行提供技术参考。

英文摘要:

      In order to reduce the aerodynamic lift and drag acting on the tail car of high-speed train during operation and improve the operation stability and energy-saving level, three tail vortex generator design schemes inspired by biomimetic principles were proposed. These designs were derived respectively from the pectoral fins of flying fish, the wings of peregrine falcons, and the dorsal fins of sailfish. Numerical simulations were conducted using the improved delayed detached eddy simulation (IDDES) method based on the SST (Shear Stress Transport) k-ω two-equation turbulence model. The numerical simulations were conducted on the aerodynamic lift and drag of high-speed train based on determining the computational domain, mesh division and boundary condition definitions. Moreover, the influence mechanisms of generators on the wake flow structures were explored from the perspectives of surface pressure distributions on the tail car nose, rear velocity fields, and three-dimensional vortex structures. The results show that the aerodynamic lift of models I-Ⅲ tail car has been significantly reduced, with average reduction rates of 38.5%, 40.4%, and 51.3%, respectively, the aerodynamic drag of the entire train has slightly decreased, with average drag reduction rates of 2.1%, 2.4%, and 3.1%, respectively when the train runs at speed between 200km/h and 400km/h. The vortex generator obstructs the airflow around the nose of the tail car, leading to alter the range and value of positive pressure in this area which fundamentally contributes to the reduction in aerodynamic lift and drag of the tail car. By analyzing of the main characteristics of the velocity field and wake vortex at the rear of the train, it is shown that the vortex generator can significantly improve the wake flow structure and effectively attenuate vortex intensity. Among the three designs, the sailfish-inspired Model Ⅲ exhibited the best overall performance, followed by the peregrine falcon-inspired Model Ⅱ and the flying fish-inspired Model I. The research can provide technical reference for reducing the aerodynamic lift of the tail car and ensuring the safe operation of the train.