Aerodynamic Characteristics Analysis of a High-speed Train under Heavy Rainfall Conditions
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摘要: 基于标准κ-ε双方程湍流模型和拉格朗日离散相模型,研究强降雨条件下列车前端计算区域长度的取值。在此基础上,分析不同车速、不同降雨强度下的高速列车气动特性,并与无雨条件下的计算结果进行比较。研究表明,列车前端计算区域长度应达到雨滴运动水平距离的1.5倍。降雨强度增加,列车周围雨滴浓度整体上增大。雨滴越靠近尾车,浓度越大。车速越大,雨滴飞溅程度越大,飞溅的距离越远。在强降雨条件下,列车的整车阻力、头车阻力、中车阻力均随降雨强度和车速的增加逐渐增大;尾车阻力随降雨强度增加而减小,随车速增加而增大。气动阻力变化的百分比随着降雨强度的增加而增大,随着车速的增加而减小。Abstract: Based on standard κ-ε double equation turbulence model and Lagrange discrete phase model, the value of computational domain's length in front of the train under heavy rainfall conditions is studied in this paper. On this basis, aerodynamic characteristics of high-speed trains under different speed and rainfall intensity are analyzed, and the simulation results are compared with those under no rain conditions. The results show that the length of the computational domain in the front of the train should reach 1.5 times of the horizontal distance of raindrop movement. With rainfall intensity increasing, raindrop concentration around the train increases overall. The closer the raindrops get to the tail train, the higher the concentration is. The greater the speed is, the greater the splash and the distance are. Under heavy rainfall conditions, the drag force of the whole train, the head train and the middle train increases gradually with the growth of rainfall intensity and speed. The drag force of the tail train decreases with the growth of rainfall intensity, whereas, it increases with the growth of speed. The percentage change of the drag force increases with the increase of rainfall intensity and decreases with the increase of speed.
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表 1 降雨参数
降雨强度/(mm·h-1) 雨滴直径/mm 雨滴末速度/(m·s-1) 质量流量/(kg·s-1) 100 2.91 7.95 2 710.19 300 3.76 8.69 7 501.01 500 4.23 8.95 11 902.82 700 4.58 9.09 16 073.74 900 4.85 9.18 20 080.94 表 2 计算区域尺寸
计算区域总长度/m 头车前端距入口距离/m 头车前端距出口距离/m 700 400 300 839 539 300 936 636 300 1 034 734 300 1 132 832 300 1 230 930 300 表 3 整车阻力值对比
计算区域长度/m 700 839 936 1 034 1 132 1 230 L a0 1.1a 1.3a 1.5a 1.7a 1.9a 阻力/N 10 475 10 482 10 538 10 791 10 754 10 804 变化率/% 0 0.07 0.6 3.02 2.66 3.14 -
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