基于边界层控制的高速列车减阻技术

Drag reduction technology of high-speed train based on boundary layer control

为减小高速列车在运行过程中的气动阻力,提出一种基于边界层控制的减阻技术。以CRH3高速列车为研究对象,通过在车体表面加设球窝非光滑表面来控制边界层的湍流特性,实现列车运行减阻效果;通过PRO/Engineer三维软件建立了高速列车模型、参数化的球窝模型和计算域模型,在不影响研究效果的前提下,对高速列车模型进行简化处理以减少数值仿真计算周期;为使网格能够更好地贴合流线型车体和球窝非光滑表面,采用ICEM CFD软件对计算域进行非结构网格划分;在考虑列车表面粗糙度对气动阻力的影响工况下,应用商业流体软件FLUENT中的k-ε湍流模型对列车在300km·h^(-1)明线运行工况下的列车外流场进行数值仿真分析。仿真结果表明:只在尾车加设球窝非光滑表面更有利于列车减阻,且随球窝的半径、深度和阵列距离的增大,列车的气动阻力均呈先下降后上升的趋势;当球窝阵列距离为350mm,球窝半径为80mm,球窝深度为10mm时,球窝非光滑表面的减阻效果最好,此时气动阻力为2 220.4N,没有加设球窝非光滑表面的列车气动阻力为2 967.9N,减阻率可达25.19%。可见,采用球窝非光滑表面来改变边界层湍流特性是降低列车气动阻力的有效途径。

A drag-reduction technique based on boundary layer control was proposed to reduce the aerodynamic drag during the operation of high-speed train. Taking CRH3 as an example, the turbulence characteristics of boundary layer was controlled by mounting ball sockets non-smooth surface on the surface of vehicle body to achieve train’s drag reduction. The models of high-speed train, parametric ball socket and computational domain were established by means of PRO/Engineer software, and the body model of high-speed train was simplified without any impact to the research effect in order to reduce numerical simulation computing cycle. The non-structure grid partition of computed field was carried out by ICEM CFD software to enable the grids to better fit in with streamlined body and ball sockets non-smooth surface. In consideration of the effect of train’s surface roughness on the aerodynamic drag,the k-ε turbulence model in commercial fluid software FLUENT was applied to conduct numerical simulation analysis of outside flow field in open air at the running speed of 300 km·h-1. Simulation result shows that only placing the ball sockets non-smooth surface on the tail of train is more conducive to reduce the aerodynamic drag. Train’s aerodynamic drag first decreases and then increases with the increase of the radius, depth and array distance of ball sockets. When the ball socket non-smooth surface is placed on the tail of train, and the array distance, radius and depth of ball sockets are 350, 80 and 10 mm, respectively, the drag reduction effect is best. The aerodynamic drag for the ball socket non-smooth surface is 2 220.4 N compared to 2 967.9 N without placing ball sockets, so the drag reduction rate is up to 25.19%. Obviously, using ball sockets non-smooth surface to change the turbulence characteristics of boundary layer is an effective way to reduce train’s aerodynamic drag. 2 tabs, 18 figs, 30 refs.