主动吹气防雪方案研究：减阻效果显著，方案1更优

本文采用了UDF程序自定义雪粒在流场中的受力状态和转向架区域离散相的边界条件，计算了雪粒在主动吹气作用下的沉积特性，并对两种主动吹气方案进行了评估，主要结论如下：

(1) 在吹气作用下，转向架区域的压力分布有了很大的变化，从而整车的压差阻力也随之变化。随着吹气速度增加，列车的行驶阻力降低，在吹气速度为4m/s时，方案1减阻率高达19.55%，方案2的减阻率从为10.06%，从而避免了使用导流板预防积雪时带来列车行驶阻力增大的情况。

(2) 转向架表面的摩擦速度在吹气作用下发生了改变，从而影响雪粒沉积的稳定性。吹气使得转向架区域的流场特性发生了变化，上扬的流线减少，从而进入转向架区域的雪粒数量减少，达到预防积雪的效果。

(3) 结合吹气所需能量和列车减阻所节约的能量对设计方案进行评估，方案1由于吹气口更靠近转向架舱前端，列车减阻更为明显，且方案1对整个转向架的防雪效果更为突出，即在额外增加同等能量的情况下，能减少更多的雪粒堆积。

5 Summary

This article uses UDF program to customize the force state of snowflakes in the flow field and the boundary conditions of the discrete phase in the steering gear area, and calculates the sedimentation characteristics of snowflakes under active blowing. Two active blowing schemes are evaluated, and the main conclusions are as follows:

(1) Under blowing, the pressure distribution in the steering gear area has changed significantly, and the pressure difference resistance of the entire vehicle has also changed. As the blowing speed increases, the running resistance of the train decreases. When the blowing speed is 4m/s, the drag reduction rate of scheme 1 is as high as 19.55%, and the drag reduction rate of scheme 2 is 10.06%, thus avoiding the increase in running resistance of the train when using guide plates to prevent snow accumulation.

(2) The friction speed on the surface of the steering gear changes under blowing, which affects the stability of snowflake sedimentation. Blowing changes the flow field characteristics in the steering gear area, reduces the up-flow lines, and reduces the number of snowflakes entering the steering gear area, achieving the effect of preventing snow accumulation.

(3) Combining the energy required for blowing and the energy saved by reducing the train's drag, the design scheme is evaluated. Scheme 1 has a more significant reduction in running resistance because the blowing port is closer to the front of the steering gear cabin. Scheme 1 also has a more prominent anti-snow effect on the entire steering gear, which can reduce more snow accumulation under the same additional energy.