This paper presents experimental and numerical approaches to systematically investigate the aerodynamic characteristics of streamlined box girder at angles of attack (AoA) of up to 12°. The effects of AoA on the pressure characteristics and total forces are first studied through wind tunnel experiments. Based on three-dimensional large-eddy simulations (3D LES), the flow topology is investigated to study the influence mechanism of AoAs. The results show that the flow topology around the section can be divided into three types: (i) completely attached flow pattern as |α| ≤ 4°; (ii) separated-reattached flow pattern as 6°≤|α|≤8°; (iii) fully separated flow pattern as |α| ≥ 10°. The combination of experimental and numerical results presents a deep understanding of the aerodynamic characteristics of a streamlined box girder and reveals the relationships between the pressure features and flow topology. The pressure characteristics and total forces are very sensitive to the flow separation and reattachment. At small AoAs, the flow attaches to the bridge section, the mean and RMS pressure, total force, as well as streamwise correlations change slightly with AoAs. Besides, the shear layer is a laminar pattern and has less impact on the span-wise correlations. Moreover, the vortices in the wake remain successive in the span-wise direction, and the Strouhal numbers are larger. On the other hand, with the increase of AoAs, large separation bubbles can be observed around the bridge section. Especially for fully separated flow pattern as |α| ≥ 10°, the shear layer no longer attaches to the bridge section and the separation bubble is longer than the section width. Accordingly, the mean and RMS pressure, total force, as well as streamwise correlations increase significantly. Besides, the shear layer is a turbulent pattern, and the turbulent fluctuations in wake become complex and less organized in the span-wise direction, then the S_t is lower than others.

本文提出了实验和数值方法来系统地研究流线型箱梁在最大迎角（AoA）为12°时的空气动力特性。首先通过风洞实验研究了AoA对压力特性和总力的影响。基于三维大涡模拟（3D LES），研究了流动拓扑，研究了AoAs的影响机理。结果表明，该断面周围的流动拓扑可分为三种类型：（i）完全附着的流动模式为|α|。≤4°；（ii）分离-再附着流型为6°≤|α|≤8°；（iii）完全分离的流型为|α| ≥10°。实验结果和数值结果的结合对流线型箱梁的空气动力学特性有深入的了解，并揭示了压力特征与流动拓扑之间的关系。压力特性和总力对流分离和重新附着非常敏感。在较小的AoAs处，流量会附着在桥段上，平均压力和RMS压力，总力以及流向相关性随AoAs的变化而略有变化。此外，剪切层是层状图案，对跨度相关性影响较小。此外，尾流中的旋涡在翼展方向上保持连续，并且斯特劳哈尔数较大。另一方面，随着AoAs的增加，可以在桥接部分周围观察到较大的分离气泡。特别是对于完全分离的流型|α| ≥10°时，剪切层不再附着在桥段上，并且分离气泡的长度大于段宽。因此，平均压力和RMS压力，总力以及流向相关性显着增加。此外，剪切层是湍流模式，尾流中的湍流波动变得复杂，在展向方向上的组织性较差，因此S _t低于其他。