Abstract This paper investigates the aerodynamics of a stationary model of an interior railway carriage inside a long-span truss-girder bridge in a wind tunnel. Effects of principle parameters of the truss bridge-girder configuration on the aerodynamics were examined, including bridge wind angle of attack (α), truss bridge-girder solidity ratio (Φ, projected area to envelope area ratio), and aspect ratio (B/D, truss bridge-girder width to height ratio). By varying α, the tested pressure distribution of the carriage model was analyzed in terms of the underlying flow physics of the carriage-bridge interaction. Consequently, the schematic flow patterns were inferred and subsequently utilized to expound the variations in the mean and fluctuating aerodynamic force coefficients. The results indicate that qualitatively the aerodynamic interaction of the truss bridge-girder on the carriage model is characterized by the shielding effect caused by upstream truss members, the suppression of underbody vortex-shedding due to the girder lower deck, and the quasi-Reynolds number effect on the upstream carriage shoulder. Compared to the results of the carriage model without the truss bridge-girder, the shielding effect reduces the mean drag force, whereas the suppression of underbody vortex shedding decreases the mean rolling moment and all the fluctuating forces. The quasi-Reynolds number effect surfaces as α varies given that the inflow Reynolds number is held constant, thus altering the aerodynamic forces abruptly. For the variation of the other two truss bridge-girder configuration parameters (Φ and B/D), qualitatively similar carriage-bridge interaction on the carriage aerodynamics was observed, although with some quantitative differences. The imperfect spanwise correlation of sectional aerodynamics was also observed as mostly owing to the shielding effect formed by the diagonal truss members. In addition, the influence of carriage-bridge interaction on the bridge aerodynamics was also examined and briefly discussed.

中文翻译：

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大跨度桁架梁桥内固定车厢侧风气动特性

摘要 本文研究了风洞中大跨度桁架梁桥内部铁路车厢静止模型的空气动力学特性。研究了桁架桥梁构型主要参数对空气动力学的影响，包括桥梁风攻角（α）、桁架桥梁密实度比（Φ，投影面积与包络面积比）和纵横比（B/ D、桁架桥梁宽高比）。通过改变 α，根据车厢-桥梁相互作用的基本流动物理学分析了车厢模型的测试压力分布。因此，推断出示意性流动模式，随后将其用于阐述平均和波动的空气动力系数的变化。结果表明，桁架桥梁在车架模型上的气动相互作用定性表现为上游桁架构件的屏蔽效应、梁下桥面对车身底部涡旋脱落的抑制以及准雷诺数对上游车肩的影响。与没有桁架桥梁的车厢模型的结果相比，屏蔽效应降低了平均阻力，而底部涡旋脱落的抑制降低了平均滚动力矩和所有波动力。考虑到流入雷诺数保持恒定，准雷诺数效应面随着 α 的变化而变化，从而突然改变空气动力。对于另外两个桁架桥梁配置参数（Φ 和 B/D）的变化，在车架空气动力学上观察到质量上相似的车桥相互作用，尽管在数量上有一些差异。还观察到截面空气动力学的不完美展向相关性主要是由于对角桁架构件形成的屏蔽效应。此外，还检查并简要讨论了车桥相互作用对桥梁空气动力学的影响。