Abstract Discretely distributed side-surface openings have a stabilizing effect on box girders against galloping. This research intends to further investigate the relationship between the size of the openings and galloping instability with respect to aerodynamic response and aerodynamic damping. An additional objective is to explain the stabilization mechanism against galloping owing to the openings. A series of wind tunnel tests was carried out on rectangular cylinders with different-sized openings that were non-dimensionalized as the Opening-area Ratio (OR), which is the ratio of the total-openings area to half of the front-surface area. At high wind velocities, increasing the OR from 0 to 0.75 increased the aerodynamic damping, and the separated shear layer gradually approached the model’s trailing edge. Increasing it above 0.75 resulted in a decrease of the aerodynamic damping and the separated shear layer reattaching to the model. As OR increased, the galloping onset increased accompanied by the decrease in Strouhal number. Thus, the rectangular cylinder showed good galloping stability owing to the openings, which promoted the reattachment of the separated shear layer on the side surfaces, effectively increasing the body width-to-depth ratio. This research contributes to an innovative method to stabilize rectangular cylinder-like bluff bodies against galloping instability.

中文翻译：

---

侧表面开口对矩形圆柱飞驰不稳定性的影响

摘要 离散分布的侧表面开孔对箱梁有抗飞移的稳定作用。本研究旨在进一步研究开口尺寸与气动响应和气动阻尼方面的不稳定性之间的关系。另一个目的是解释防止因开口而引起的飞驰的稳定机制。在具有不同尺寸开口的矩形圆柱体上进行了一系列风洞测试，这些开口被无量纲化为开口面积比 (OR)，即总开口面积与前表面积一半的比值. 在高风速下，将 OR 从 0 增加到 0.75 会增加气动阻尼，分离的剪切层逐渐接近模型的后缘。将其增加到 0 以上。75 导致空气动力学阻尼降低，分离的剪切层重新附着到模型上。随着 OR 的增加，疾驰开始增加，伴随着 Strouhal 数的减少。因此，矩形圆柱体由于开口而表现出良好的驰骋稳定性，促进了分离的剪切层在侧表面的重新附着，有效地增加了车身宽深比。这项研究有助于采用一种创新方法来稳定矩形圆柱状钝体以防止飞驰不稳定。这促进了分离的剪切层在侧表面的重新附着，有效地增加了车身宽深比。这项研究有助于采用一种创新方法来稳定矩形圆柱状钝体以防止飞驰不稳定。这促进了分离的剪切层在侧表面的重新附着，有效地增加了车身宽深比。这项研究有助于采用一种创新方法来稳定矩形圆柱状钝体以防止飞驰不稳定。