宽体近流线型箱梁表面涡激力分布机理研究

VIV performance of streamlined box girder with large width will be carried out in this project, with different flow field and width to height ratio by segment model test. The effect of wind field and width on the vortex excitation force distribution, spanwise correlation of vortex-induced forces will be researched. Basing on the section model test results and fluid dynamics software, a three dimensional numerical model is set up to recurrence the VIV. Then, reason of multi-lock-in regions of streamline box girder and effect of width length ratio will be found out. Regularity of separation and reattachment of airflow occurring more than once will be found out. Aerodynamic force contribution of different section position on the vortex-induced force will be studied and the best characterization point will be found out. At last, the universally spanwise correlation of vortex-induced forces model will be set up..Results of this project can provided a reference during the design, construction and operation state of large width streamlined box girder.

近流线型箱梁因其较好的气动力特性而被广泛应用于大跨度桥梁中。随着近流线型箱梁表面宽度不断增加，气流被风嘴分离后，在箱梁表面发生多次分离和再附，使其涡激振动变得比较复杂。.本项目拟针对宽体近流线型箱梁的涡激振动性能，开展不同宽高比的节段模型测压试验，研究风场及宽度效应对其表面涡激力分布的影响，宽体近流线型箱梁的涡激力展向相关性。以试验结果为依据，结合流体动力学软件，建立三维断面数值，复现涡激振动全过程，揭示宽体近流线型箱梁双涡激振动锁定区成因，风场和宽高比对涡激力的影响机理。研究不同宽高比下气流发生多次分离和再附的规律，断面不同位置气动力对整体涡激力相关性的贡献，建立具有普遍适用性的宽体近流线型箱梁的涡激力展向相关模型。.研究结果可为宽体近流线型箱梁的设计、施工与运营提供参考依据。

宽体近流线型箱梁具有良好的气动性能，易于建造和维护。项目以典型的宽体近流线型箱梁为研究对象，进行了风洞实验，并借助CFD数值模拟技术，研究了施工态和成桥态宽体近流线型箱梁的气动力特性和流场分布变化状况。探讨了均匀流和非均匀流、紊流强度、积分尺度对宽体近流线型箱梁气动特性的影响。研究了不同宽高比宽体近流线型箱梁上表面分离涡泡的大小和再附点分布情况，表面风压随宽度增加的变化。从竖弯、扭转基频的卓越程度及尾流涡脱形态分析了风攻角对宽体近流线型箱梁涡振性能的影响机理，揭示了宽体近流线型箱梁双涡激振动锁定区成因，阐述了宽体扁平箱梁的竖弯、扭转涡激振动与漩涡脱落间的反馈机制。