列车运行时，由于与周围空气发生相对运动，列车前面的空气被压缩形成正压，尾部的空气稀薄，产生涡流，形成前后两端的压力差，这部分阻力称为压差阻力。同时，列车整个外部表面与空气相摩擦，产生摩擦阻力。此外,因机车、车辆突出部分及转向架等在运行时，扰动空气，产生扰动 When the train is running, due to the relative movement with the surrounding air, the air in front of the train is compressed to form a positive pressure, and the tail air is thin and eddy current is generated, forming a pressure difference between the front and the back. This part of resistance is called differential pressure resistance. At the same time, the entire outer surface of the train rubs against the air and creates frictional resistance. In addition, due to locomotives, vehicle protrusions and bogies in operation, the disturbance of air, resulting in disturbance