中文摘要：

采用计算流体力学方法对土堤式挡风墙阶梯式设计进行了数值模拟，分析挡风墙后列车的气动性能。研究结果表明：采用阶梯式设计后，列车所受到的横向力、升力和倾覆力矩明显减小，中间客车的横向力、升力和倾覆力矩分别最大减少88.7%，58.3%和75.6%；车体迎风面较大面积的强正压转变为大部分负压，车体顶部负压减小，整个车体基本处于一个负压环境中，因而受力情况明显好于原挡风墙下的车体受力。同一阶梯高度下，机车受到的横向力和倾覆力矩最大，第一节客车受到的升力最大；不同车速下，车体横向力、倾覆力矩随阶梯高度变化的拟合曲线基本相同，且在阶梯高度0.6~1.0 m之间变化平缓。

英文摘要：

Numerical simulation of multistep design of the earth type windbreak wall was performed by using CFD method, and the aerodynamics of the train behind the windbreak wall was analysed. The results show that when the multistep design scheme is proposed, side force, lift force and overturning moment of the train decrease, which of middle passenger car reduce by 88.7%, 58.3% and 75.6% to the maximum, respectively. The pressure on windward surface of the train changes from positive to negative and negative pressure on roof of the train decreases. The whole train body is in a negative pressure environment so that the stress condition is obviously better than that of the original wind-break wall. At the same step height, the side force and overturning moment of locomotive are the most, but the lift force of the first passenger car is the largest. At different vehicle speed, the fitted curves of side force, overturning moment with step vertical height are nearly the same, while they change gently in the range of 0.6-1.0 m of the step height.