Wind tunnel testing of FLexible Advanced aeroelastic Models of BRidGe cables

An experimental campaign was carried out at the Jules Verne Climatic Wind Tunnel – Dynamic Unit SC1 at the Centre Scientifique et Technique du Bâtiment (CSTB) in Nantes, France. The project aimed to improve wind testing facilities and develop an experimental methodology for laboratory simulation and investigation of airflow conditions around cables with climatic and technological roughness in particular- the study of Wind Induced Vibrations (WIV) of bridge cables. Advanced flexible aeroelastic models with the closest possible representation of the real shape of the cables, including the characteristic shape of cables covered with glaze ice, spiral pattern of the helical strake, etc… allow to achieve higher natural modes (up to 4 and higher) with the ability to fine-tune natural frequencies for testing the realistic Reynolds number range, as well as ensuring the 3-dimensional nature of cable-wind interactions in controlled laboratory conditions. The project involves the use of the close to real cable diameter for the model (110 mm) as well as a large ratio of diameter to length (1:40). It is also necessary to have space for placing fastening and tensioning equipment and cables. Thus, key parameter required for carrying out the tests is a wind tunnel cross section where the model stand can be placed. Within the framework of the project, 2 models with different surface roughness were tested: smooth model (as reference) ; model of cable with asymmetrical ice accretions – this model was tested at 3 different angles of attack on the ice "edge". The steel core pretension for both models was set at 2 levels tuned for the frequencies of first natural mode f = 5 and 10 Hz. All models configurations were tested at 2 orientations with yaw angles 0° and 15°.本实验研究于法国南特市法国建筑科学技术中心（CSTB）的儒勒·凡尔纳气候风洞——动态单元SC1内开展。 本项目旨在升级风力测试设施，并开发一套实验测试方法，用于实验室模拟与研究带有气候与工艺诱导表面粗糙的缆索周围的气流场，尤其聚焦于桥缆的风致振动（Wind Induced Vibration, WIV）研究。 本项目采用的先进柔性气动弹性模型可最大程度还原缆索的真实外形，包括覆雨凇的缆索特征外形、螺旋防振条的螺旋结构等。该模型可实现最高达4阶及以上的固有振型，且可微调固有频率以适配实际雷诺数范围，同时在可控实验室条件下还原缆索与风相互作用的三维特性。 本项目采用的模型缆索直径接近实际桥缆（110 mm），且径长比达1:40，同时需预留足够空间以安装紧固、张拉设备及缆索。因此，本次测试的核心参数要求为风洞截面需可容纳模型支架。 本项目共测试了两款不同表面粗糙度的模型： 光滑基准模型（作为对照）； 带有非对称覆冰的缆索模型——该模型分别在冰面"边缘"的3个不同攻角下开展测试。 两款模型的钢芯预张力均设置为两个档位，分别适配一阶固有频率f=5 Hz与10 Hz。所有模型构型均在偏航角0°与15°两种工况下完成测试。