主动格栅紊流场对典型主梁颤振导数影响的研究

On the Influence of Active Grid Turbulence Field on Flutter Derivatives of Typical Main Girder

为研究紊流积分尺度对桥梁颤振导数的影响,选取了理想平板、流线型箱梁以及高宽比1∶6矩形断面三种气动外形渐变的典型断面,采用主动格栅模拟了二维大积分尺度紊流场,利用强迫振动装置测试了主动格栅紊流场中三种断面节段模型的颤振导数,并与均匀流场试验值进行了对比。试验结果表明,紊流积分尺度对颤振导数的影响随断面钝化逐渐减弱;主动格栅二维紊流对流线型断面颤振导数影响较小,无明显趋势性变化;对钝体矩形断面影响显著,并且随折减风速增加而加剧,其气动阻尼项导数由正向负衰减显著,有利于改善结构颤振性能。

In order to investigate the effect of turbulence integral scale on the flutter derivatives of bridge deck,three kinds of typical pneumatic shape gradually changed deck section were selected as study objects,including the ideal flat plate,the streamlined box girder and the rectangular section with height to width aspect ratio 1∶6.Adopting active grid to simulate two dimensional large integral scale turbulence field,the flutter derivatives of models located in active grid turbulence field and with three typical cross section were measured based on a forced vibration device.Above data were compared with experimental data taken from uniform flow field.Experimental results indicate that the influence of turbulence integral scale on the flutter derivatives is weakened gradually with the cross section passivation.The influence of two-dimensional turbulence generated by active grid on the derivatives of streamlined box girder section is less,without obvious trend change;but its influence on flutter derivatives of blunt rectangular cross section is obvious,and increases with the reduced wind speed.Its aerodynamic damping term derivative is significantly improved by the forward negative attenuation,which is beneficial to improve the structural flutter performance.