GOALI/Collaborative Research: Nonlinear Energy Dynamics of Aerodynamically Coupled Oscillators

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Wind energy became the largest renewable energy generated in the US in 2019, and this energy is projected to be a signification portion of all generated electrical energy in the nation within a decade. The introduction of large wind turbines has been considered to be an important direction, as they can result in an increase in generated power. However, wind turbines may not be the best solution for all wind speeds and locations such as building roof-tops. As an alternative, a set of piezoelectric harvesters, which can be used with small foot-prints and at low wind speeds will be studied. These harvesters represent an example of an oscillatory system, in which the coupling between the structural members is dominated by fluid forces that are generated during motions through an air flow. Other oscillatory systems with similar fluid (aerodynamic) coupling include rotating blades in turbine generators, compressors, and turbo fans. Through support of this Grant Opportunity for Academic Liaison with Industry (GOALI) award, fundamental studies will be pursued to develop and extend the knowledge base on aerodynamically coupled oscillators. A salient impact is expected to be the advancement of our understanding of the nonlinear behavior of systems involving fluid-structural-electromechanical interactions. Through experimental demonstrations of the feasibility of these systems, it is expected that one can design and build piezoelectric energy harvesters for use in building systems and tethered unmanned vehicle systems. This work will usher in a new generation of researchers trained to use multi-disciplinary tools suited for study of nonlinear dynamics of energy harnessing systems.Building on prior efforts on nonlinear oscillators, aeroelasticity, experimental fluid mechanics, and active materials, a team of researchers from academia and industry will pursue the common goal of developing a fundamental understanding of aerodynamically coupled piezoelastic oscillators. The group will conduct original wind tunnel experiments to understand flow induced oscillations of thin airfoil oscillator arrays and bluff body oscillator arrays and study the energy distribution in the system responses across a variety of flows. Informed by experimental findings and guided by industry experience, modeling and simulation efforts will be undertaken to uncover nonlinear phenomena and nonlinear instabilities including Hopf instabilities. On the fundamental side, one of the outcomes will be an enhanced understanding of the behavior of the coupled oscillators with aerodynamic coupling, the nature of this coupling for different flows and oscillator configurations, and the associated nonlinear fluid-structure interactions. On the application side, this work will result in performance characterization tools for energy harnessing arrays based on streamlined and bluff body oscillators.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.