横风作用下铁路货车篷布气动力数值模拟计算

Numerical simulation of aerodynamic force on tarpaulin of railway vehicle under cross wind condition

基于三维、不可压、定常Navier-Stokes方程和k-ε双方程湍流模型,采用零厚度壁面模拟货车篷布,建立横风作用下篷布内外空间三维流场计算模型,对铁路货车D型篷布所受气动升力进行数值模拟计算;分析货车在大风地区运行时,横风风速、货物装载高度、货物装载形状以及货物沉降对其气动力的影响,得到篷布在不同工况下所受气动载荷。研究结果表明：当列车速度一定时,篷布所受到的气动升力系数近似与横风风速成正比;篷布所受气动升力随着货车装载高度的增加而显著增加,超车帮为0.7 5 m时篷布受到的升力系数比超车帮为0.4 5 m时大2 8%;超车帮装载（圆弧顶）时,篷布受到的气动升力系数比不超车帮装载（三角型顶）时大2 8.3%;当篷布和货物之间间隙处于0.0 2~0.1 2 m之间时,随间隙增大,篷布所受气动升力增大,间隙为0.1 2 m时的篷布气动升力系数比间隙为0.0 2 m时大1 4.5%;数值计算与试验结果相对误差7.1%,证明了数值计算方法的正确性。

Based on the three-dimensional, incompressible and steady Navier-Stokes equation and k-ε turbulence model, the pomplex three-dimensional flow field model around the tarpaulin was built when the freight vehicle runs through the wind area. The zero-thickness wall was used to simulate the tarpaulin in those models. Numerical simulation was adopted to carry out the aerodynamic force on the tarpaulin of railway freight vehicle in cross winds. The effect laws of the tarpaulin aerodynamics force were gained which were caused by the wind speed, the height of the cargo loading, the figure of the cargo loading and the sedimentation of the cargo. The aerodynamic forces of tarpaulins were gained when the freight vehicle runs under different conditions. The results show that when the speed of train remains unchanged, the aerodynamic lift coeffcient of the tarpaulin is proportional to the wind speed. The lift force of the tarpaulin increases significantly with the increase of the height of the cargo loading, the lift force coefficient of 0.75 m tarpaulin height is larger than that of 0.45 m in height, and the increase value is 28%. When the figure of the cargo loading is circular arc, the lift force coefficient of the tarpaulin is much greater than when the figure is triangular, and the increase value is 28.3% When the clearances between the tarpaulins and goods inside 0.02-0.12 m, the lift force of the tarpaulin increase with the increase of clearance. When the clearance is 0.12 m, the lift force coefficient is 14.5% larger than when the clearance is 0.02 m. The results show that the numerical calculation results and experimental results have a relative error of 7.1%, which proves the numerical calculation method is correct.