诱发H形桥梁断面风振的空气能量输入特征

AIR-INPUT-ENERGY CHARACTERISTICS OF H-SHAPE BRIDGE DECKS INDUCED BY WIND VIBRATION

采用计算流体动力学(CFD)的方法,分析了H形断面颤振临界状态下的绕流特征。采用分块分析方法研究颤振过程中气流能量在模型表面不同区域的输入特性以及模型表面的旋涡演化过程对模型表面气动力和气动能量输入特性的影响。分析结果表明模型表面的旋涡演化造成了靠近迎风侧挡板的模型区域的表面压力变化具有较强的规律性,而背风侧挡板附近的模型区域的表面压力变化则没有明显的规律。分块分析的结果显示模型靠近迎风侧挡板的上表面区域是吸收气流能量的部位,而气流输入到模型背风侧挡板附近区域的能量具有波动特性,使得空气输入到模型的总气动能量在一个完整的振动周期内也具有较强的波动特征,从而造成H形断面颤振发生时出现持时较长的大幅扭转振动。

The flow characteristics around an H-shape bridge deck in its flutter was studied by the computational fluid dynamics （CFD） numerical method. The effect of the vortex evolution on the model different region＇s aerodynamic force and pneumatic energy was researched by block analysis. The research shows that the vortex evolution caused by the changeable characteristics of the surface pressure on the model area near the windward side platen had strong regularity. While the change of pressure on the model region near the leeward side baffle had no obvious rule. Block analysis show that the model up side surface areas near the windward side platen absorbed the air energy, and the air energy input to the model surface near the leeward side platen was fluctuate. Thusly, the total air energy input to the model was also fluctuate, which caused a long time larger amplitude of torsional vibration of H-shape bridge decks in the flutter.