基于凸包非光滑表面的高速列车减阻技术

为减少高速列车在运行中的空气阻力,提高列车运行效率、节约能耗,提出凸包非光滑表面减阻技术应用于高速列车领域。文中以CRH3型高速列车为研究对象,通过在车体的头部和尾部加设凸包来控制湍流特性,以达到减阻效果。首先利用PRO/Engineer建立非光滑表面CRH3型头车+中间车+尾车的简化模型,将模型导入ICEM CFD软件并根据计算精度的需要划分不同网格区域,得到较高质量的非结构网格,再应用FLUENT软件中的k-ε湍流模型对稳态运行速度为300 km/h时的列车进行模拟仿真,计算列车空气阻力,对比分析凸包的阵列距离、半径和高度对减阻性能的影响。并从头车、尾部的压力图和附近速度矢量图两方面来反映凸包非光滑表面对高速列车压差阻力的影响;从湍流动能和湍流强度角度解释凸包非光滑表面对高速列车黏性阻力变化的作用。仿真结果表明:列车的气动阻力随凸包阵列距离的增大而减小、随凸包半径的减小而减小、随凸包高度的减小而先减小后又增大;当凸包半径为40 mm,阵列距离为460 mm,凸包高度为10 mm时,列车具有最好的减阻效果;相对于光滑表面列车,在头车加设凸包而尾车不加设时,头车阻力可小至1239 N,头车减阻率为10.67%,总阻力为3591 N,总减阻率为3.80%。可见,通过在头车加设凸包可以改变边界层湍流特性达到减小列车气动阻力的效果。期望文中的研究为高速列车后期减阻方法研究提供一定的参考。

Drag Reduction Technology for High-speed Train Based on Non-smooth Surface of Convex Hull

In order to reduce the air resistance of high-speed trains in operation,improve the efficiency of train operation and save energy,this paper puts forward the application of convex hull non-smooth surface drag reduction technology in high-speed trains.Taking CRH3 as the re?search object,and controls the turbulence characteristics by adding convex hulls on the head and tail of the car body to achieve the drag reduc?tion effect.Firstly,a simplified model of non-smooth surface CRH3 which include head vehicle,intermediate vehicle,tail vehicle were estab?lished by using PRO/Engineer.Then the model was imported into ICEM CFD software and different mesh areas are divided according to the need of calculation accuracy to obtain a higher quality unstructured grid.After that,the turbulence model in FLUENT software was used to simulate the train with steady-state running speed of 300 km/h to calculate the air resistance of the train and compare the influence of the ar?ray distance,radius and height of the convex hull on the drag reduction performance.The influence of the non-smooth surface of the convex hull on the differential pressure of the high-speed train is reflected from the pressure diagram of the head vehicle,tail vehicle and the nearby velocity vector diagram.Effect of non-smooth surface of convex hull on viscosity resistance change of high speed train was explained from perspective of the turbulence intensity and the turbulence kinetic energy.The simulation results shows that the aerodynamic drag of the train decreases with the increase of the distance of the convex hull array,decreases with the decrease of the convex hull radius,and decreases with the decrease of the convex hull height.The train has the best drag reduction effect when the radius is 40 mm,the array distance is 460 mm and the height of the convex hull is 10 mm.Compared with the smooth surface train,when the front vehicle is provided with a convex hull and the tail vehicle is not added,the head car resistance is 1239 N,the head vehicle drag reduction rate is 10.67%,the total resistance is 3591 N,and the total drag reduction rate is 3.80%.Obviously,the turbulence characteristics of the boundary layer can be changed to reduce the aerodynamic drag of the train by adding a convex hull on the head vehicle.It is expected that the research in this paper will provide a refer?ence for the study of the drag reduction method for high-speed trains.