气动弹性系统本征正交分解降阶模型精度的参数影响研究

发布时间：2018-01-11 20:00

本文关键词：气动弹性系统本征正交分解降阶模型精度的参数影响研究　出处：《西安交通大学学报》2016年11期 　论文类型：期刊论文

【摘要】：为了快速分析跨音速非线性气弹系统的颤振边界和响应特性,通过本征正交分解(POD)降阶方法建立了基于CFD的气动弹性降阶模型(ROM)。实现过程包括对非线性定常CFD流场的小扰动泰勒分解,建立基于CFD的全阶线性化模型;再通过POD方法得到流体ROM;耦合结构动力学方程构成基于CFD的气弹ROM。以国际气弹标模AGARD 445.6机翼为研究对象,系统研究了ROM建立过程中初始流场、响应时间步长和样本数据等重要参数对于模型精度的影响,并将ROM应用于颤振边界的预测。研究表明:作为线性化方程建立的定常流场,若收敛性不够,易导致线性化模型不稳定甚至发散;响应计算中,时间步长若选取过大将会导致数值振荡、发散;为捕捉更多的非线性流场特性,系统激励后POD样本的产生需保证足够的数据采集时间;所建立的ROM具有同原始非线性CFD/CSD系统同样的精度,是一个低维度状态空间数学模型,可直接用于系统特性分析和颤振抑制等设计。相比CFD/CSD耦合计算,ROM在计算效率上提高了3~6个量级。
[Abstract]:In order to rapidly analyze the flutter boundary and response characteristics of a transonic nonlinear Aeroelastic system. An Aeroelastic order reduction model based on CFD is established by means of the intrinsic orthogonal decomposition (POD) method. The realization process includes the small disturbance Taylor decomposition of the nonlinear steady CFD flow field. The full-order linearization model based on CFD is established. Then the fluid ROM was obtained by POD method. Aeroelastic rom based on CFD is constructed by coupled structural dynamics equation. The initial flow field in the process of establishing ROM is systematically studied by taking the international Aeroelastic model AGARD 445.6 wing as the research object. The effect of response time step size and sample data on the accuracy of the model is discussed. ROM is applied to predict the flutter boundary. The study shows that the steady flow field established as a linear equation is not convergent enough. It is easy to lead to instability and even divergence of linearization model. In response calculation, if the time step is too large, it will cause numerical oscillation and divergence. In order to capture more nonlinear flow field characteristics, the generation of POD samples after system excitation needs to ensure sufficient data acquisition time. The established ROM has the same accuracy as the original nonlinear CFD/CSD system and is a low dimensional state space mathematical model. It can be directly used in the design of system characteristic analysis and flutter suppression. Compared with the CFD/CSD coupling calculation, the computational efficiency of the rom is improved by 3 ~ 6 orders of magnitude.
【作者单位】：西安交通大学机械结构强度与振动国家重点实验室;西安交通大学航天航空学院;
【基金】：国家自然科学基金资助项目(11272005;11472206;11371288;11511130053) 陕西省自然科学基金资助项目(2016JM1007)
【分类号】：V211.47
【正文快照】： 飞行器气动弹性研究飞行器结构与气动力相互耦合关系,是典型的流固耦合振动问题。在空气跨声速流动阶段,由于流体的可压缩性导致激波运动、涡脱落等强非线性效应,升力面法、偶极子法等传统线性化方法很难处理跨声速阶段流体非线性气动力。目前,基于CFD/CSD耦合计算飞行器的气

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