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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。
In order to reduce the aerodynamic drag of high-speed train during operation, a drag reduction technology based on boundary layer control is proposed. Taking the CRH3 high-speed train as the research object, the turbulent characteristics of the boundary layer are controlled by adding a ball-and-socket non-smooth surface to the car body surface to achieve the drag reduction effect of the train. A high-speed train model is established by PRO / Engineer 3D software, Ball-nest model and computational domain model. Without affecting the research effect, the high-speed train model is simplified to reduce the numerical simulation calculation cycle. In order to make the mesh better fit the streamlined body and the ball and socket non-smooth surface , Using ICEM CFD software to calculate the domain unstructured mesh; considering train surface roughness on the aerodynamic drag conditions, the application of commercial fluid software FLUENT k-ε turbulence model of the train at 300km · h ~ ( -1) train outflow field under the condition of bright line running is numerically simulated and analyzed. The simulation results show that the train drag reduction is more beneficial only for the non-smooth surface of the ball and socket at the tail car, and the aerodynamic drag of the train tends to decrease firstly and then increase with the increase of the radius, depth and array distance of the ball socket; When the ball and socket array distance is 350mm, the ball and socket radius is 80mm, the ball and socket depth is 10mm, the ball and socket non-smooth surface has the best drag reducing effect. At this time, the aerodynamic drag is 2204.4N, no ball and socket non-smooth surface The aerodynamic drag of the train is 2 967.9N, the drag reduction rate can reach 25.19%. Therefore, it is an effective way to reduce the aerodynamic drag of trains by changing the boundary layer turbulent characteristics by using a non-smooth spherical surface.