可控脉动风场下矩形断面复气动导纳特性研究

The complex aerodynamic admittance functions of rectangular cylinder in controllable fluctuating wind fields

为了研究不同脉动风参数及结构运动状态对钝体断面复气动导纳的影响,介绍了在CFD中产生竖风向及顺风向谐波脉动风场的方法,该方法幅值可控且能多频率组合;对宽高比为4∶1矩形断面,采用CFD识别其在不同风攻角及三种谐波幅值下的升力和阻力复气动导纳;对比了多频率组合谐波及竖向、扭转简谐运动下的气动导纳。结果表明:在0°风攻角下,升力气动导纳与实验值吻合较好,验证了数值模拟的正确性;较大的风攻角和谐波幅值均对复气动导纳有显著影响;在多频率谐波及断面不同运动状态下,升力复气动导纳基本保持不变,但扭转运动能增大高频处的阻力复气动导纳值。

In order to study the effects of pulsing wind parameters and structural motion state on the complex aerodynamic admittance functions(AAF)of bluff body,a new procedure to generate the vertical-and along-wind harmonic inflows in CFD simulations is proposed.Based on the N-S equation and the boundary condition,this method can well control the amplitude and generate multi-frequency harmonic inflows.The lift and drag AAFs of a rectangular section with aspect ratio of 4 are identified under different wind attack angles and three different harmonic amplitudes.The aerodynamic admittances are compared under the multi-frequency harmonic combinations as well as the vertical and torsional motions.It is shown that the lift admittance at null attack angle is in good agreement with the experimental data.The wind angle attack and harmonic amplitude have a significant impact on the complex admittance.In addition,the lift AAFs remain almost the same in multi-frequency inflows and different motions,while the torsional motion can increase the value of drag AAF at high frequencies.