Fluid-structure interactions and instabilities

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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.