Exploiting the Wind Energy Resource through Aeroelastic Vibration and Torsional Flutter

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Wind energy is an important component of the United States program for renewable energy. As part of this effort, large-scale systems (onshore and offshore wind turbines) have been thoroughly investigated. On the opposite side of the “spectrum”, micro-scale wind energy has been examined for the purposes of deployment of small sensors that are self-sufficient and self-recharging. Both technologies have reached an advanced maturity. In contrast, the meso-scale range, i.e., the intermediate scale of a single-family household or a street block, is largely unexplored and has good potential for growth and innovation. This project addresses the need for clean energy at the meso-scale level, using a simple and compact wind-based energy harvester. The power generator exploits the torsional aeroelastic instability (i.e., torsional flutter) of a blade-airfoil apparatus. The technology will be viable since its operational mechanism is simpler than other, similar harvesting technologies in the recent past. The research plan will include fabrication and testing of a reduced-scale prototype unit. The project results will demonstrate how the apparatus can be implemented in urban settings and provide a valuable energy source for electric and mechanical systems.The project will examine the technical feasibility of the wind energy harvester that exploits torsional flutter. Torsional flutter is a single mode aeroelastic instability phenomenon, which triggers a diverging vibration of a flexible body. The project will make use of preliminary results, in which a numerical model was employed to predict mechanical vibrations and induced currents. The investigation will include analytical, numerical and experimental stages. The objectives of this research are: 1) advancement of the current theory and analytical modeling of flutter energy “scavenging”; 2) assembly of a prototype unit used in the verification and validation studies in the laboratory; and 3) deployment and monitoring of the unit at full scale. The first objective will consider the modeling of post-critical dynamics, nonlinear aeroelastic force and response, and the calibration of the key parameters of the wind energy harvester. The second objective will be accomplished through the design of a reduced-scale unit, followed by validation and verification through wind tunnel tests, which will include operational efficiency. Finally, an exploratory study will be carried out through the deployment at full scale on a building roof. The educational plan includes a set of outreach activities and demonstrations for various audiences (e.g., students, engineers).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.