指数脉冲强迫激励CFD模型运动的气动参数识别法  

System identification of aerodynamic parameters based on CFD modeling and exponential pulse excitation

作　　者：祝志文[1] 顾明[2] 陈政清[1] 

机构地区：[1]湖南大学风工程研究中心,湖南长沙410082 [2]同济大学土木工程防灾国家重点实验室,上海200092

出　　处：《振动工程学报》2007年第2期133-139,共7页Journal of Vibration Engineering

基　　金：国家自然科学基金(50678067);中国博士后研究基金(2005038452);上海市博士后科研资助计划(06R214148)

摘　　要：计算流体动力学(CFD)模拟是获得桥梁断面颤振导数的主要方法之一。提出了一种基于CFD计算气动力,建立气动模型并经模型仿真快速识别颤振导数的新方法。该方法采用具有连续频谱分布且位移光滑的指数脉冲序列为CFD模型运动的输入,通过数值模拟得到作用在模型上的气动力。利用已知的输入和气动力建立起反映系统气动力特征的离散时间气动模型。然后利用该模型仿真系统在简谐位移输入的气动力响应,再基于该输入和模型仿真输出识别颤振导数。该方法在竖弯和扭转方向各自仅需一次CFD模拟,无需重复进行CFD计算,能显著减小CFD计算颤振导数的工作量。进行了薄平板颤振导数的识别,研究结果与T heodorsen平板理论解、薄平板风洞试验值的一致性,证明了研究方法的可靠性和有效性。Computational fluid dynamics （CFD） simulation is one of main methods to obtain bridge deck flutter derivatives, however, it is time-consuming since large amounts of computation should be performed. In this paper, based on the single vertical and torsional CFD computation and the foundation of aerodynamic models, a novel approach is presented, and through which the flutter derivatives at arbitrary reduced wind speed among the interesting range can be fleetly extracted. This method employs the exponential pulse time series as input to excite CFD model, which can provide slick aerodynamic forces acting on the body through CFD simulation. Then discrete time aerodynamic models, defined among interesting range of frequency, can be trained based on the CFD input-output relationship, those models can be implemented thereafter to simulate aerodynamic response for simple-harmonic input of displacement with suitable frequency. Finally, flutter derivatives can be identified based on the input and model output time series. Flutter derivatives of a thin plate is investigated by using present method. It is seen that the identified results, the Theodorsen theoretic solutions of the ideal flat plate and flutter derivatives of a thin plate from wind tunnel tests share the same trends, which demonstrates the reliability and efficiency of present approach.

关 键 词：颤振 CFD 系统识别 指数脉冲 模型仿真 

分 类 号：V215.34[航空宇航科学与技术—航空宇航推进理论与工程]