基于流向涡扰流的大跨桥梁自激振动流动控制

By closely relying on the good effectiveness of streamwise vortices on suppressing spanwise vortex, this project focuses on the characteristics of wind-induced flow field around long-span bridge girders and the properties of wind-induced self-excited vibration under the streamwise vortices flow control through integrating theoretical analysis, numerical simulation and wind tunnel test. This project attempts to reveal the flow control mechanism based on streamwise vortices in improving the characteristics of wind-induced flow field around bridge deck sections as well as suppressing the vortex induced vibration and flutter, so as to develop the flow control method based on streamwise vortices to increase wind-resisting ability of long-span bridges. Firstly, the spanwise vortices properties and the flow control mechanism based on streamwise vortices of typical bluff bodies are studied. Secondly, the generating methods of streamwise vortices is studied, and then the relations between characteristic parameters of streamwise vortices and the control parameters are established. Thirdly, the simulation methods of flow field around long-span bridges influenced by streamwise vortices and inflow is developed. Fourthly, the flow control effect on suppressing wind-induced self-excited vibration and flow control mechanism based on streamwise vortices are studied. Last, the flow control design method of wind-induced self-excited vibration of long-span bridge girders based on streamwise vortices is developed. The project will give a new perspective for solving key wind-resisting problems for development of long-span bridges. Research results will further enrich and develop wind-resisting theory of bridges, and it is of great significance to improve the ability of disaster prevention and mitigation of major projects in China.

本项目综合运用理论分析、数值计算以及风洞试验研究手段，紧紧围绕流向涡对于展向涡的有效抑制作用，研究流向涡扰流作用下的大跨桥梁箱形主梁风致绕流场特性及风致自激振动特性，揭示流向涡扰流方法对于改善主梁断面风致绕流场特性以及抑制主梁风致涡振与颤振的流动控制机理，旨在发展基于流动控制方式提高大跨桥梁抗风能力的流向涡扰流控制方法。首先，研究典型钝体绕流场展向涡特征与流向涡扰流控制机制；之后，研究桥梁主梁扰流流向涡发生方式并建立相关控制参数与流向涡特征参数之间的关系式；然后，研究来流与流向涡扰流共同作用下桥梁主梁流场数值模拟方法；之后，研究基于流向涡扰流的桥梁主梁自激振动流动控制效果及机理；最后，研究基于流向涡扰流的桥梁主梁自激振动流动控制设计方法。本项目研究将为解决大跨桥梁发展所面临的抗风难题提供新的视角，预期成果将丰富和发展大跨桥梁抗风理论，对提升我国重大工程结构防灾减灾能力具有重要意义。

本项目借助用理论分析及数值计算研究手段，提出钝体绕流三维稳定性分析方法，揭示钝体断面流场中流向涡对于展向涡的抑制机理；提出了适用于大跨桥梁主梁的流向涡发生方式，采用风洞试验手段验证其对主梁自激振动的控制效果并总结控制规律；利用尾流高频测速及流场可视化试验等研究手段，揭示了流向涡扰流对于桥梁主梁自激振动的流动控制机理；建立了来流与流向涡扰流共同作用下桥梁主梁流场数值模拟方法；提出基于流向涡扰流方式的桥梁自激振动流动控制设计方法。