Reduced-Order-Model-Based Flutter Analysis at High Angle of Attack
Reduced-Order-Model-Based Flutter Analysis at High Angle of Attack
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DOI：
10.2514/1.32285
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发表时间：
2007-11
影响因子：
2.2
通讯作者：
Weiwei Zhang;Zhengyin Ye
中科院分区：
文献类型：
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作者：
Weiwei Zhang;Zhengyin Ye
具有高度柔性三角翼的配置被考虑用于下一代无人飞行器（UAV）。三角翼流场以大迎角涡结构为主，其中最突出的是前缘涡。Ye和Zhao b[1]采用非线性升力线法计算了大迎角时三角翼的气动载荷。随着计算机技术的发展，计算流体力学（CFD）技术已被应用于三角翼诱导的旋涡模拟。研究表明，雷诺数对初涡的影响较小，可以用欧拉码对初涡和气动载荷进行模拟；其不足之处在于不能模拟由黏度影响引起的二次涡。将CFD与计算结构动力学（CSD）直接耦合方法应用于deltawing气动弹性分析。Gordnier等[3,4]将Euler/ Navier-Stokes编码与非线性植物单元耦合，研究了柔性三角翼在大迎角下的颤振问题。CFD和CSD直接耦合方法[5 - 7]也被用于三角翼小迎角（<5°）的非线性颤振仿真。直接气动弹性模拟方法的局限性是计算时间昂贵。为了解决计算效率和计算质量之间的矛盾，近十年来许多研究人员转向基于cfd的非定常气动降阶建模（ROM）来提高气动弹性计算效率。Dowell and Hall [8], Lucia et . [9]， Zhang and Ye[10]对ROM及其在非线性气动弹性研究中的应用进行了综述。目前非定常气动载荷的rom计算方法主要有两种。一种是基于适当正交分解（POD）的降阶建模方法，另一种是基于结构模态识别技术的气动建模方法。本文采用的是第二种方法。Zhang[11]比较了基于rom的方法和CFD直接模拟方法的效率。基于rom的方法在保持精度的前提下，效率提高了12个阶。Zhang使用基于cfd的ROM进行气动伺服弹性分析[12]和主动控制跨声速颤振抑制[13]。
C ONFIGURATIONS with a highly flexible delta wing are considered for the next generation of unmanned air vehicles (UAV). Delta wing flowfield is dominated by vortical structures at high angle of attack, the most prominent is called leading-edge vortex. Ye and Zhao [1] used a nonlinear lifting line method to compute the aerodynamic loads of the delta wing at high angle of attack. With the development of computer technology, computational fluid dynamics (CFD) technique has been used in the simulation of delta wing-induced vortical flow. The study [2] shows that the Reynolds number affects primary vortex slightly, and so Euler codes can be employed to simulate the vortex and aerodynamic loads; the shortness is that it cannot simulate the secondary vortex caused by the effect of viscosity. The CFD and computational structural dynamics (CSD) direct coupling method has been used in aeroelastic analysis of deltawing.Gordnier et al. [3,4] coupled Euler/ Navier–Stokes codes and nonlinear plant element to study the buffet problem of the flexible delta wing at high angle of attack. The CFD and CSD direct coupling method [5–7] has also been used in the nonlinear flutter simulation of delta wing at small angle of attack (<5 deg). The limitation of the direct aeroelastic simulation method is the high cost of the computational time. To solve the contradiction between computational efficiency and computational quality, many researchers turn to CFD-based unsteady aerodynamic reduced-order modeling (ROM) to improve the aeroelastic computational efficiency in the last decade. Dowell and Hall [8], Lucia et al. [9], and Zhang and Ye [10] present some overviews of ROM and its applications on nonlinear aeroelastic research. There are two kinds of methods for ROMof unsteady aerodynamic loads at the present time. The one is the proper orthogonal decomposition (POD) based reduced-order modeling method, the other is aerodynamic modeling based on structural modes by using identification technology. The second method is used in this work. Zhang [11] compared the efficiency between the ROM-based method and the CFD direct simulation method. Efficiency can be improved by 1 2 orders with accuracy still retained by ROM-based method. Zhang used CFDbased ROM to perform aeroservoelastic analysis [12] and transonic flutter suppression by active control [13].