Flow-induced vibrations and instabilities of structures

本研究的长期目标是：(I)充分了解圆柱体结构的动力学行为；(Ii)建立适当的预测性理论模型，并在实验上进行验证。短期目标如下[括号内有申请]。1.通过线性和非线性分析/CFD模型和实验[海洋开采、液化天然气生产、碳氢化合物储存、甲烷水合物开采]，研究了沿其长度方向具有可变密度和流速的悬臂管和圆柱壳在其自由端排放或抽吸流体的动力学，同时在其外部受到受限轴向流的作用。2.探索新的流动路径策略，以利用流动诱导的激励和阻尼对流动速度和流动方向的依赖性，既可以延迟/防止颤振[上文§1中的应用]，也可以产生接近零的阻尼[低阻尼微机械/纳米器件]。使用几何/材料周期性介质和连续的功能梯度材料来产生无源和有源管段，以插入管道中，以扰乱波传播并减少声音传输[液压系统中的噪声过滤]。通过分析/CFD建模和实验(换热器、核反应堆、海上石油/天然气勘探和生产)，研究了横向约束圆柱形支柱在轴流和拖曳圆柱体中的非线性动力学。所有这些工作都可能立即对加拿大的石油和天然气、航空和发电行业有用，并在这些领域培训HQP。

The long-term objectives of this research on flow-induced vibrations/instabilities of cylindrical structures with internal and/or external axial flow are: (i) to gain full physical understanding of the dynamical behaviour and (ii) to generate appropriate predictive theoretical models and validate them experimentally. The short-term objectives are as follows [with applications in brackets]. 1. The dynamics of cantilevered pipes and cylindrical shells discharging or aspirating fluid at their free end, with variable density and flow velocity along their length, and simultaneously subjected to confined axial flow on their exterior, via linear and nonlinear analytical/CFD models and experiments [ocean mining, LNG production, hydrocarbon storage, methane hydrate exploitation]. 2. The exploration of novel flow-path strategies to exploit the dependence of flow-induced excitation and damping on flow velocity and flow direction, either to delay/prevent flutter [applications in §1 above] or to produce near-zero damping [low-damping MEMS/nano devices].3. The use of geometric/material periodic idscontinuities and functionally graded materials to produce passive and active pipe segments, for insertion in pipelines in order to disrupt wave propagation and diminish sound transmission [filtering noise in hydraulic systems].4. The nonlinear dynamics of transversally confined cylindrical struts in axial flow and of towed cylinders, via analytical/CFD modelling and experiments [heat exchangers, nuclear reactors, offshore oil/gas exploration and production].All of this work is potentially immediately useful to the Canadian oil-and-gas, aeronautical and power- generation industries and for training HQP in these fields.