桥梁气弹响应分析的时域气动模型

为了解决传统桥梁气弹响应分析方法因非定常不可压流CFD计算量巨大而导致的效率低下问题,提出一种桥梁气弹响应分析的新方法。该方法采用频域特性可调的广谱指数脉冲时间序列强迫桥梁断面运动,并通过CFD计算得到作用在桥梁断面上的气动力,然后由桥梁断面的运动位移和气动力时程,通过系统识别建立起桥梁绕流系统的时域离散时间气动模型。最后以具有扭转自由度的薄平板在初始位移激励下的运动为例,进行了振动响应计算和气弹全过程分析。研究结果表明:该方法能显著提高桥梁气弹响应分析的计算效率。

Time-domain Aerodynamic Model of Aeroelastic Response Analysis of Bridges

In order to solve the low efficiency problem caused by large calculation amount of non-stationary computational fluid dynamics(CFD) used in conventional aeroelastic response of bridges,a novel method was presented which was efficient and expedient to evaluate aeroelastic response of bridge based on time-domain aerodynamic models.Firstly,unsteady aerodynamic forces acting on bridge sections were obtained by using CFD with forced exponential pulse displacement.In order to develop the discrete-time aerodynamic models in time-domain,system identification was applied to displacement input and aerodynamic output of fluid system from the CFD simulation.Then,the obtained aerodynamic models were used in place of the unsteady CFD simulation,which could predict aerodynamic forces acting on the section to bridge displacement.Finally,aeroelastic system of a thin plate with only torsional degree of freedom in wind was employed to predict its aeroelastic response.Results show that the time saving associated with the use of the aerodynamic model in coupled aeroelastic solution is significant,and present method can rapidly predict aeroelastic response of structure at future instant of time.