高速列车流线型转向架与底部导流板的气动减阻效果研究

Aerodynamic drag reduction of streamlined bogie and bottom deflector of high-speed train

为适应高速列车进一步提速的更低气动阻力实际需求,针对CR400AF型高速列车动车转向架和带头型简化车体,应用底部流动导向控制思想,采用附加轻质易造型材料包覆原有部件的理念,开展转向架各部件流线型化和车体底部导流板综合减阻效果的验证试验与数值仿真研究。验证试验选择有无导流板的流线型转向架带简化车体模型,在3种试验速度工况下阻力试验值与仿真值误差均少于10%,验证了数值仿真的可靠性,带导流板试验模型较不带导流板试验模型均有减阻。数值仿真研究运用Realizable k-ε湍流模型,采用切割体笛卡尔网格划分技术,并在边界层内采用棱柱层网格,控制第1层网格的厚度,确保y+值能满足壁面函数要求。经稳态明线运行的仿真模拟网格无关性检验后,探究了流线型动车转向架与导流板组合运用的气动减阻特性及效果。对比了流线型动车转向架与安装导流板前后动车转向架、简化车体以及转向架舱上的阻力变化情况和压力分布变化情况,分析了转向架区域的流场结构变化。数值仿真结果表明:流线型设计的动车转向架相较于原始动车转向架有一定的减阻效果,在400 km/h的运行速度下减阻率达到1.08%。流线型设计动车转向架与导流板组合运用后,转向架区域的流场结构显著改善,总体气动减阻效果明显,总气动阻力减少了5.87%。

In order to further reduce the aerodynamic drag on the bottom of higher-speed train,the idea of bottom flow control was applied on the bogie of CR400AF type high-speed train.By covering the original components with additional lightweight and easy-to-shape materials,the streamlined design of bogie was achieved.Validation tests and numerical simulation on the streamlining of the bogie components and the comprehensive drag reduction of the deflector were carried out.The test model with a streamlined bogie with or without deflector was selected.The error between test and simulated drag values at all three test speeds was less than 10%,verifying the reliability of the numerical simulation.The test model with deflector has reduced the drag compared to the test model without deflector.In simulation,realizable k-εturbulence model is adopted.Cartesian mesh is used to mesh computational domain with simplified train head and bogie.Prismatic layer mesh is used to capture the boundary layer viscous effect.The thickness of the first layer mesh is controlled to ensure that the y+value could meet the wall function requirements.After the mesh independence test of the steady-state open-air operation simulation,the aerodynamic drag reduction characteristics of the streamlined bogie in combination with deflector are investigated.The aerodynamic drag,pressure distribution and flow field structure of the original bogie/simplified body,streamlined bogie/simplified body,streamlined bogie/simplified body/deflector are compared and analyzed.The numerical simulation results show that the streamlined bogie has a good drag reduction effect compared with the original bogie,with a drag reduction rate of 1.08%at 400 km/h.After the combined application of the streamlined bogie and deflector,the flow field structure of the bogie area has been significantly improved,the total aerodynamic drag is reduced by 5.87%.