Fluid-structure interactions and instabilities

本提案的研究主题是由流体力引起的柔性结构的振动和不稳定性，特别是由于结构动力学和由此产生的流体力之间的相互作用而产生的结构运动。两个具体的问题将被检查：横流钝体和气动弹性诱导飞机结构的不稳定性。第一个问题，横流中的钝体，是由各种情况下发生的工业问题引起的，例如：热交换器管阵列，架空导体束和海上结构。主要目的是了解导致流体诱发振动和不稳定的机制，并为此类设备的设计人员和/或操作人员提供指导。现有的工作表明，要建立这些流固相互作用的可靠分析模型，需要比目前对横流中圆柱群的非定常间隙流体力学有更好的理解。这是本研究的主要目的之一，它将通过实验研究和数值模拟来实现。这项工作将有助于更好地理解圆柱阵列中的非定常流体力学，从而更好地模拟伴随的流体弹性不稳定性。气动弹性研究集中在非线性对翼型气动弹性响应的影响上。主要目的是研究现有气动弹性参数识别技术的有效性，并开发新的和改进的方法。将采用实验和数值方法相结合的方法来进行这个项目。这项工作的最终目的是发展改进的飞行试验技术，用于识别具有结构非线性的飞机的颤振边界。

The main theme of the research presented in this proposal is vibrations and instabilities of flexible structures caused by fluid forces, and particularly where the structural motion arise as a result of interactions between the structural dynamics and the fluid forces generated thereby. Two specific problems will be examined: bluff bodies in cross-flow and aeroelastically-induced instabilities of aircraft structures.The first problem, bluff bodies in cross-flow, is motivated by industrial problems occurring in a variety of situations, such as: heat exchanger tube arrays, overhead conductor bundles and offshore structures. The primary objective is to understand the mechanisms leading to flow-induced vibrations and instabilities and provide guidelines for designers and/or operators of such equipment. Existing work has shown that to develop reliable analytical models of these fluid-structure interactions requires a much better understanding than presently exists for the unsteady interstitial fluid mechanics of groups of cylinders in cross-flow. This is one of the primary aims of this research, it will be achieved using both experimental investigations and numerical simulations. This work will lead to a better understanding of the unsteady fluid mechanics in cylinder arrays, and hence, to superior modeling of the concomitant fluidelastic instabilities.The aeroelastic investigations are centred around the effect of nonlinearities on the aeroelastic response of airfoils. The main objectives are to investigate the efficacy of existing techniques for aeroelastic parameter identification, and to develop new and improved methodologies. A combination of experimental and numerical methods will be used to pursue this project. The ultimate aim of this work is to develop improved flight test techniques for the identification of flutter boundaries for aircraft which possess structural nonlinearities.