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Designing Large Efficient Wind Turbines

September 30, 2015

CEE Associate Professor Luca Caracoglia was awarded an $155K NSF for "Collaborative research: Active Control of Nonlinear Flow-Induced Instability of Wind Turbine Blades under Stochastic Perturbations".

This research is conducted in collaboration with the University of Massachusetts - Amherst, Profs. Yahya Modarres-Sadeghi, Matt Lackner and Christopher V. Hollot.


Abstract Source: NSF

Wind turbine blades continue to grow in length to extract more energy from the wind. This trend results in more flexible blades that are more susceptible to flow-induced instabilities, which can lead to sudden and catastrophic failures. The onset of these dynamic instabilities can be altered by the inherent uncertainties in the system, and is dangerously close to the wind turbine's designed operational speed. This poses a threat to the integrity of the system. Being able to control these instabilities is critical for the successful operation of future wind turbine blades. The goal of this project is to examine and understand appropriate methodologies to actively control nonlinear flow-induced instabilities of large wind turbine blades, considering their inherent stochastic nature. This project will support the ability to design and operate larger, more flexible wind turbine blades, which will eventually increase energy capture and reduce the cost of energy offshore wind. This research is timely since the current energy plan of the United States strongly emphasizes the need for alternative energy production from sources such as offshore wind energy. The findings of this research will be disseminated at different levels by creating new modules for different courses, hosting high school classes, and increasing research opportunities for students.

This research will consider a fully-coupled continuous fluid-structure interaction model of the flexible, rotating blades, accounting for varying blade shapes and cross-sections, as well as bending and torsional properties. We will use this nonlinear model to examine the effect of a number of non-deterministic system parameters on the onset of flow-induced instabilities, using perturbation methods as well as stochastic calculus, and to investigate strategies to actively control these flow-induced instabilities using advances in bifurcation control, probabilistic robustness and multivariable robust control. The Intellectual Merit of this project lies in a unified methodology to advance the fundamental understanding and analysis of control strategies for large wind-turbine systems, which involve the interaction of a flexible structure (the blade) and unsteady flow. These systems contain combined nonlinearities from the structure, the fluid flow around it, and the interaction between the fluid and the structure. This research is transformative because it provides fundamental insights into the underlying physics and control of nonlinear stochastic fluid-structure interaction systems with non-uniform properties, including future wind turbine blades, by combining several different areas of expertise.