基于结构动力学方法的气动弹性分析

【作者】 周文博；

【导师】 唐国安；

【作者基本信息】 复旦大学 ， 飞行器设计， 2010， 硕士

【摘要】 由于现代飞行器朝高速度、轻结构、大柔性、超机动方向发展,导致其弹性结构和流体之间的强耦合,飞行器遭遇了更加严重的气动弹性问题。随着高性能计算机的发展,计算流体动力学/计算结构动力学(CFD/CSD)耦合数值模拟已能精确预测气动弹性响应,但计算规模庞大,耗时久。因此,在保证精度的同时如何提高计算效率是气动弹性力学领域的研究热点和难点。本文研究了一种结合通用计算结构动力学程序的气动弹性方法：对于气动与弹性的耦合模型,给出气动力的频域公式,并表示成有理多项式,通过特定的等价变换,能够推导出与结构动力学方程完全相似的、关于求解变量的二阶常微分方程组。于是,可以在计算结构动力学框架下实现气动弹性问题的分析和计算。此方法将通用计算结构动力学程序的功能与试验或数值分析得到的气动力模型相结合,简化了气动弹性的耦合分析、提高计算效率。本文的创新点在于：对非定常气动力进行等价变换,得到与结构动力学方程完全相似二阶常微分方程组,并结合通用计算结构动力学程序对二元机翼气动弹性耦合系统进行了颤振分析。本文的主要工作内容为：1)从有理多项式气动力表达式出发,以Theodorsen气动力模型为例,通过气动力有理多项式拟合及特定的等价变换,建立了气动力在时域内的二阶常微分方程组2)使用通用计算结构动力学程序,实现气动弹性的耦合分析。3)建立了闭环控制模型,应用次最优控制律,进行颤振的主动抑制研究更多还原

【Abstract】 Modern aircrafts is required of high speed, light structure, great flexibility, and super maneuverability, which leads to strong interaction between the flexible structure and the surrounding flow. Consequently aircrafts suffers a more serious aeroelastic problem. With the development of high-performance computers, the computational fluid dynamic (CFD)/computational structure dynamic (CSD) numerical simulation can predict the aeroelastic response accurately, but the simulation remains too computationally expensive to be used in multi-disciplinary settings and the aeroelastic analysis of complicated systems. So the problem of how to improve the computational efficiency is a hot topic.In this paper, the coupling for pneumatic and flexible model, given the frequency domain aerodynamic formula, and expressed as a rational polynomial of the equivalent transformation, to derive the full dynamic equations with a similar structure, on the two unknown variables order ordinary differential equations. Thus, in the calculation of structural dynamics can be achieved under the framework of Aeroelastic analysis of the problem and calculation. This method will be general computing structure, function and dynamics program testing or numerical analysis and the combination of aerodynamic models, simplifies analysis of aeroelastic coupling and increases efficiency.The main innovations in this paper are as follows:1. Using the Theodorsen aerodynamics as an example, adapting rational polynomial fitting and specific equivalent transformation to establish aerodynamics second order ordinary differential equations in the time domain.2. Using the general computational structural dynamics program, to achieve a flexible coupling of aerodynamic.3. Establish a closed-loop control model, application sub-optimal control law, for the active suppression of flutter.更多还原