附加攻角效应对颤振稳定性能影响

Influence of static wind additive attack angle on flutter performance of bridges

用强迫振动装置识别攻角从-3°^+4°细化步长变化为1°的洞庭湖二桥主梁断面气动导数;将该气动导数拟合成折减风速、攻角的三维曲面,只需获取某一有效攻角的具体数值即可自动求得所有气动导数值。通过在ANSYS中的三维TABLE表存储各攻角的气动导数,自动计入附加攻角对颤振稳定性影响。全模态颤振分析结果表明,附加攻角效应可降低该类桥梁的颤振临界风速。若按常规试验方法以3°攻角为步长进行气动导数插值计算,颤振分析有可能得到错误结论。

Aerodynamic derivatives of Dongting Lake bridge girder sections were identified by forced vibration in wind tunnel,with the angle of attack changing in step of 1 °from -3 °to ＋4 °.The aerodynamic derivatives were fitted to form a three-dimensional surface made up by reduced velocity,angle of attack and aerodynamic derivatives.Only if a specific value of the effective angle of attack is given,all aerodynamic derivatives can be automatically obtained.The data of aerodynamic derivatives were stored in a three-dimensional TABLE in ANSYS,the effect of additional angle of attack on flutter stability was naturally concerned.A full-mode flutter analysis indicate that the additional angle of attack may decline the critical flutter speed of typical bridges and the influenced extent is according to the type of bridges.