CAREER: Controlling fluid structure interactions within an oscillating foil turbine array

An oscillating foil, or a wing undergoing a combined rotational and heaving motion, is a physical model of flapping animal flight or aquatic propulsion. Inspired by these biological systems, this proposal explores an oscillating foil operating as a turbine to harvest kinetic energy from rivers or tidal channels. Specifically, this research will investigate the unsteady flow physics within a close-packed array of oscillating foils and uncover methods for enhanced power production. This knowledge will advance marine energy turbine development, a renewable energy technology complementary to wind and solar farms. The broader impacts of the education plan are designed to reach students throughout the academic pipeline, improving recruitment and retention of students in renewable energy and mechanics. The high heave and pitch kinematic motion of an oscillating foil generates a two-dimensional vortex wake whose structure is intricately linked to the flapping kinematics. As an additional benefit, oscillating foils can actively modulate the area of swept flow and share this swept area with adjacent and complementary foils to boost energy density. Despite these kinematic advantages, there has been little research on active control of kinematics within clusters of foils. This research will utilize a computational model combined with reinforcement learning to interact with the unsteady wake environment and elucidate constructive mechanisms for vortex dynamics and cooperative control within a tightly grouped cluster of 3 to 4 foils. This will be performed through an advanced computational methodology interwoven with a reinforcement learning algorithm that enables exploration of nontrivial oscillation kinematics and exploitation of the energy potential in unsteady inflow conditions. Results of the proposed work will develop a framework for the unsteady flow physics within tightly clustered oscillating foils, improving efficiency and energy density, and improving modeling and design tools for coordinated control in non-ideal flow conditions. The educational objectives will utilize specific activities to improve recruitment, retention, and climate for women undergraduate and graduate students, and develop renewable energy modules for K-12 outreach. Integration of research and education is facilitated through a new freshmen design course, undergraduate research, and targeted mentoring efforts through student groups. 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.