基于大涡模拟的风致超高层建筑复杂运动数值模拟方法研究

Wind and structure interaction problems become gradually important for high, flexible super tall buildings. The aeroelastic effect has to be considered when analyzing wind-induced response of super tall buildings. Comparing with wind tunnel experiment, CFD numerical simulation facilitates parameter analysis, possessing apparent advantages in structural plan and design optimization. The aeroelasticity mechanism could also be analyzed through flow visualization of CFD numerical simulation results. In this research, numerical simulation method for wind-induced vibration for super tall buildings with complex movement will be investigated. Some fundamental issues, as improvement of simulation accuracy of turbulent wind field and development of mesh updating method to complex deformation of structure, will be mainly studied. Firstly, new inflow turbulence generation method for LES, combining the improved RFG method and the recycling correction method, will be developed to improve the simulation accuracy of the turbulent wind field. Secondly, hybrid mesh updating method, adopting potential flow theory based elastic body method and tension - torsion spring method, will be developed to apply to complex deformation of structures. The conserving partitioned scheme will be adopted to build stable and effective numerical simulation platform for wind-structure -interaction problems. The proposed method will be verified by comparing the simulated aeroelastic responses for typical super tall buildings with those of wind tunnel experiment. Finally, some important issues as, properties and mechanism of the dynamic interaction between wind and eccentric super tall buildings, will be discussed applying proposed numerical method.

超高层建筑高、柔的特点，使得风与结构的相互作用问题突显，在响应分析中需考虑气动弹性效应。与模型风洞试验相比，CFD数值模拟方便参数分析，在结构的方案及优化设计阶段具有显著优势，还可通过流场显示进行结构气弹响应机理分析。本课题将研究风与超高层建筑相互复杂作用的数值分析方法，着重解决紊流风场模拟精度和结构复杂运动时流场网格更新方法等基础问题。首先，结合改进的RFG方法和循环修正法合成LES入流脉动，提高紊流风场模拟精度。其次，采用基于势流原理的弹性体法和拉伸-扭转弹簧法，发展适用于结构复杂变形的流场网格更新方法。采用守恒分区迭代求解算法，搭建稳定高效的风与结构相互作用数值模拟平台。对比分析数值计算与典型超高层建筑风洞试验结果，验证本课题方法的正确性。最后，利用数值模拟方法来讨论偏心超高层建筑结构与风动态相互作用的特性及机理等重要问题。

当前，超高层建筑的数量日趋增多，高度逐渐增加，这使得结构的风敏感性逐渐增强，风荷载成为控制结构设计的重要因素，超高层建筑的风荷载及效应问题亟待深入研究。本项目围绕超高层建筑风振气弹响应问题，采用数值分析方法主要进行了以下几方面相关研究：（1）通过研究合适的空间尺度和时间尺度参数给定方法，发展了基于MDSRFG方法的大涡模拟入流边界条件合成方法。空风洞风场大涡模拟结果显示，沿流向不同位置的模拟风场平均风剖面、三个方向紊流度剖面都能够较好地与目标风场保持一致性，模拟风速谱在低频和高频处都能够与目标谱具有较好的一致性，说明该方法可提高紊流边界层风场的模拟精度。（2）通过分别在结构周边较密网格处采用弹性体法，结构较稀疏网格处采用拉伸-扭转弹簧法，发展了结构复杂运动变形的流场网格更新方法。对商业软件Fluent和Ansys的二次开发，采用UDF编程实现耦合界面上非匹配网格的搜索配对、数据传递和流体网格更新，采用APDL (Ansys parametric design language) 语言参数化编程进行结构计算，搭建了基于能量守恒的分区迭代时间推进格式稳定高效的风与结构相互作用数值模拟计算平台，包含CFD求解模块、CSD求解模块、数据传递模块、网格更新模块等4个模块，通过编制主进程实现各模块间的相互调用，通过典型算例的比较验证了平台的有效性。（3）基于搭建的计算平台，研究分析了超高层建筑结构风振气动弹性响应，初步探讨了结构风振气弹响应机理。本项目相关研究方法和结果，可为结构抗风设计及结构风振振动控制等提供技术支撑。