高超声速间隙不确定性机翼非线性颤振研究

Hypersonic aeroelastic is one of the key issues in the design of hypersonic vehicles, wings flutter is one of the most important scientific and engineering aeroelastic problems. Although the assumption of linearity for both aerodynamics and structural dynamics is often employed in the flutter analysis, there are many examples where non-linearities exist that can have a significant effect on the flutter characteristic. Among all these several structural non-linearities, the freeplay usually gives the most critical flutter condition. The uncertainty is an important property of the freepaly of hypersonic wings under aerodynamic load and heat flux, but few results can be found in the specialized literature. In this project, the uncertainty of freepaly for hypersonic aircraft wing is took into account, and the nonlinear flutter characteristic is studied. The nonlinear flutter model of hypersonic wings with uncertainty freeplay is established first, and then, The model validation progam for flutter system with freeplay nonlinearity based on modal test is pesented. On this basis, the nonlinear flutter characteristic of hypersonic wings with freeplay nonlinearity is discussed, the effect of uncertainty parameters of freeplay on wing flutter is investigated, and the flutter stability criterion is studied. With this project, the mechanism of nonlinear flutter of wings with uncertainty freeplay will be revealed.

高超声速气动弹性技术是高超声速飞行器总体技术的重要内容之一，机翼颤振是其中的关键问题。机翼间隙是影响颤振特性的重要因素，会降低颤振系统的稳定性。在高超声速气动热-力联合作用下，机翼间隙将呈现出明显的不确定性特性，可能会影响间隙非线性颤振系统的稳定性，但目前为止还未被重视，也未见文献公开报道。本项目系统深入地开展高超声速间隙不确定性机翼的非线性颤振问题研究，包括：建立高超声速间隙不确定性机翼非线性颤振模型，探索以模态试验为主要确认试验的机翼颤振系统模型确认方案，通过模态试验完成不确定性颤振模型的确认，以此为基础，探讨高超声速机翼间隙非线性颤振特性，研究间隙不确定性参数对非线性颤振的影响，探索间隙不确定性机翼颤振稳定性规律，剖析间隙不确定性颤振机理。本项研究将有助于深刻认识和揭示间隙不确定性机翼非线性颤振现象发生的机理、条件和规律，为高超声速飞行器机翼的颤振设计与分析提供理论依据和技术储备。

高超声速气动弹性技术是高超声速飞行器总体技术的重要内容之一，机翼颤振是其中的关键问题。机翼间隙是影响颤振特性的重要因素，会降低颤振系统的稳定性。在高超声速气动热-力联合作用下，机翼间隙将呈现出明显的不确定性特性，影响间隙非线性颤振系统的稳定性，但目前为止还未被重视，也未见文献公开报道。本项目以高超声速飞行器机翼为研究对象，系统深入地开展高超声速间隙不确定性机翼的非线性颤振问题研究。首先，将高超声速飞行器机翼简化为二元机翼，采用活塞理论计算其非定常气动力，同时考虑机翼系统中的间隙非线性及间隙不确定性，通过拉格朗日方程得到高超声速不确定性机翼的非线性颤振模型。其次，对高超声速机翼间隙非线性颤振问题展开研究，提出了采用同伦分析法进行高超声速间隙非线性颤振的新思路。提出了采用低阶残差最小来获得收敛控制参数的改进同伦分析法，从而避免了在未知收敛参数情况下求解高阶近似解，同时避免求解复杂的高阶最小平方残差问题，研究了间隙非线性参数对高超声速机翼颤振特性的影响规律。再次，研究了高超声速间隙不确定性机翼的非线性颤振特性，对比了间隙均匀分布与正态分布情况下的非线性颤振特性，分析了间隙不确定性参数对非线性颤振的影响，研究间隙不确定性机翼颤振稳定性规律，探索间隙不确定性颤振机理。最后，提出了采用模态试验作为确认试验的机翼颤振系统模型确认方案，开展了多片机翼的模态试验，并根据试验数据，采用小样本置信水平理论方法完成了不确定性颤振模型的确认。本项目的研究可有助于深刻认识和揭示间隙不确定性机翼非线性颤振现象发生的机理、条件和规律，为高超声速飞行器机翼的颤振设计与分析提供理论依据和技术储备。