高速列车头型多目标气动优化设计

为提高明线运行的高速列车气动性能，以头车气动阻力和尾车气动升力为优化目标，对高速列车头型进行了多目标自动优化设计.以某新型高速列车为原型，建立了包含转向架区域的高速列车参数化模型，提取了7个设计变量，分别控制鼻尖高度、端盖开闭机构顶端高度、驾驶室车窗高度、水平最大外轮廓线横向宽度、头型中部辅助控制线凹凸度、转向架区域横向宽度和隔墙倾角，并基于计算流体动力学理论，建立了高速列车空气动力学模型.应用该模型计算作用在列车上的气动力，通过多目标遗传算法自动更新设计变量，实现了高速列车头型的自动优化设计.对优化目标与设计变量的相关性进行分析，结果表明:驾驶室车窗高度和转向架区域横向宽度对头车阻力影响最大，头型鼻尖高度和中部辅助控制线凹凸度对尾车升力影响最大；优化后得到6个Pareto最优头型，与优化前的头型相比，头车阻力最多减小3.15%，尾车升力最多减小17.05%. 

Multi-objective Aerodynamic Optimization Design for Head Shape of High-Speed Trains

To improve the aerodynamic performance of high-speed trains running in open air, an optimization design method of the head shape of high-speed trains was proposed. Taking the aerodynamic drag force of the head car and the aerodynamic lift force of the tail car as the optimization objectives, the automatic multi-objective optimization design of the head shape of high-speed trains was carried out. Based on a new type high-speed train, the parametric model of the high-speed train including bogie zones was established. Seven design variables were extracted, which control the nose height, the top height of the opening and closing mechanism of lids, the cab window height, the lateral width of the maximum horizontal contour line, the concave-convex degree of the central auxiliary control line of the streamlined head, and the lateral width and partition angle of the bogie zone, respectively. The aerodynamic models of high-speed trains were then established based on the theory of computational fluid dynamics (CFD). With the models, the aerodynamic forces acting on the trains were calculated. The design variables were automatically updated through the multi-objective genetic algorithm to achieve the automatic optimization design of the head shape of high-speed trains. In addition, the correlations between the optimization objectives and the design variables were analyzed. The results show that the cab window height and the lateral width of the bogie zone have the most influences on the drag force of the head car, while the nose height and the concave-convex degree of the central auxiliary control line have the most influences on the lift force of the tail car. After optimization, 6 Pareto-optimal head shapes are obtained. For these 6 Pareto-optimal head shapes, when compared with the head shape before optimization, the drag force of the head car is reduced by up to 3.15%, and the lift force of the tail car is reduced by up to 17.05%.