基于CFD数值模拟对大跨桥梁主梁断面颤振研究

Study on Flutter of Main Girder of Long Span Bridge Based on CFD Numerical Simulation

随着桥梁设计跨度增大,结构对风荷载作用极为敏感。采用CFD数值模拟方法研究桃花峪黄河大桥主梁断面颤振问题,根据分状态强迫振动法给出了颤振导数识别方法建立了数值计算模型,经计算得出结论:在+5°风攻角下造成竖向振幅为0.03 m所需风速约为13.2 m/s,在+3°风攻角下造成相同竖向振幅所需风速约为14.2 m/s;在+5°风攻角下造成扭转振幅为6°所需风速约为13.1 m/s,在+3°风攻角下造成相同扭转振幅为6°所需风速约为14.0 m/s,风攻角是颤振重要因素;经模拟气动流场得到主梁结构在0°、+3°及-3°攻角下颤振临界状态涡量变化情况可知随着风速增大涡量图为一对细长互不干涉正负涡量逐步增大至正负交替漩涡,在尾流处耦合成2个相互交替大漩涡。

With the increasing span of bridge design, the structure is very sensitive to wind load.Using CFD numerical simulation method to study the taohuayu the Yellow River bridge section flutter ,flutter derivatives identification method is a numerical calculation model is established according to thegivvn state forced vibration method , the calculated conclusion caused by vvrtical amplitude of 0. 03 m re-quired wind speed is about 13. 2 m/s at ＋5 DEG wind angle of attack , causing the s a m e vertical ampli-tude required about wind speed for 14. 2 m/s at ＋ 3 DEG wind attack angle is 6 degrees; caused by the torsion amplitude required wind speed is about 13. 1 m / s at ＋5 D E G wind angle of attack , causing the same torsion amplitude is 6 degrees required speed is about 14. 0 m / s at ＋3 DEG wind attack angle,wind attack angle is an important factor of flutter; aerodynamic flow field obtained by simulating girder flutter in 0 degrees , ＋ 3 degrees and - 3 degrees at critical state changes of vorticity shows as the wind speed increases the vorticity graph is a pair of elongated non-interference in positive and negative vorticity increases gradually to alternate in the wake vortex at Two mutually alternating vortices.