基于脉动风作用下的大跨度桥梁拉索风场数值模拟

Numerical Simulation of Wind Field on Large Span Bridge Cable Based on Pulsating Winds

采用Kaimal脉动风速谱,利用MATLAB模拟脉动风的瞬时风速时程并导入计算流体力学软件中,选择RNGk-ε模型,考虑在高雷诺数的作用下,对大跨度桥梁的拉索风场数值模拟。采用结构性网格建立流场模型,分别选取30 m和80 m高度处分析流场和风压力系数的变化;选取50 m高度处分析速度矢量;选取80 m高度处分析流速和迹线变化;选取拉索中心位置、拉索尾端分析拉索周围压力分布,并进行数值模拟。计算结果表明,对比文献中风洞试验的结果,流场中流体的分布特征符合类似研究的结论,可以得到合理精度的数值解;在拉索周围上、下表面形成涡街,涡流沿中轴线运动并呈现对称的形状;拉索表面压力分布和文献中风洞试验结果较吻合,并且符合工程实际。

MATLAB is used to simulate the instantaneous wind speed time history of pulsating wind and import it intocomputational fluid dynamics software by using Kaimal fluctuating wind speed spectrum, the RNG k- ε model is chosen tosimulate the wind field of long span bridges under the action of high Reynolds number. The flow field model was establishedby using structural grid, and the changes of flow field and wind pressure coefficient were analyzed at the heights of 30 m and80 m respectively. The velocity vector is analyzed at a height of 50 m, the flow rate and trace change were analyzed at theheight of 80 m. The center and the end of the cable were selected to analyze the pressure distribution around the cable, andthe numerical simulation was carried out. The calculation results showed that, the characteristics of fluid distribution in theflow field are in accordance with the conclusion of similar research, and a reasonable accurate numerical value can beobtained. Vortex was formed on the upper and lower sides of the cable, and the eddy current moved along the central axis andtook a symmetrical shape, the pressure distribution of the cable surface was consistent with that of the wind tunnel in theliterature, and in line with the engineering reality.