The key issue for developing energy-saving high-speed trains is to optimize aerodynamic performance. Therefore, the strategy of installing shields beneath bogies (SBBs) is proposed to improve the aerodynamic performance of the train further. A high-speed train Case0 without SBB and two high-speed trains Case1 and Case2 with different SBBs are established. Numerical simulations are carried out using the IDDES method to analyze the differences in the aerodynamic characteristics of the three trains. According to the findings, the largest error in surface pressure between the wind tunnel test and numerical simulation is roughly 3.6%. The aerodynamic resistance of the head, middle, and tail car of Case1 is reduced by 29.7%, 7.3%, and −7.2% in comparison to Case0, respectively, and that of Case2 train is reduced by 56.7%, 32.1%, and 17.1%. The aerodynamic resistance of the whole Case1 and Case2 is reduced by 12.2% and 37.7%, respectively, with Case2 having a more significant drag reduction effect. The vortex shedding range of Case0 is approximately 1.35 times that of Case2. Moreover, the presence and type of the SBB will affect the flow field around and behind Bogie6, resulting in a 9° difference in the wake downwash angle between Case2 and Case0. A comprehensive analysis of the surface pressure and aerodynamic forces of the train, the pressure, velocity, turbulence kinetic energy, and vortex structure of the flow field reveals that Case 2 exhibits lower aerodynamic resistance and better characteristics in the flow field. The study's findings can serve as data support and reference for the research and development of next-generation high-speed trains and installing equipment on railways.

中文翻译：

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转向架下防护罩高速列车气动特性研究

发展节能高速列车的关键问题是优化空气动力性能。因此，提出了在转向架下方安装防护罩（SBB）的策略，以进一步提高列车的气动性能。建立一列不带SBB的高速列车Case0和两列带不同SBB的高速列车Case1和Case2。采用IDDES方法进行数值模拟，分析三列列车气动特性的差异。根据研究结果，风洞试验与数值模拟之间的表面压力最大误差约为3.6%。案例1的头车、中车、尾车气动阻力较案例0分别降低了29.7%、7.3%和-7.2%，案例2列车气动阻力分别降低了56.7%、32.1%和17.1% %。Case1和Case2整体气动阻力分别降低了12.2%和37.7%，其中Case2减阻效果更为显着。Case0的涡旋脱落范围约为Case2的1.35倍。此外，SBB的存在和类型会影响转向架6周围和后面的流场，导致Case2和Case0之间的尾流下洗角相差9°。综合分析列车的表面压力和气动力、流场的压力、速度、湍流动能和涡结构，发现工况2表现出更低的气动阻力和更好的流场特性。研究结果可为下一代高速列车研发和铁路安装设备提供数据支撑和参考。