Collaborative Research: Aerodynamic-aeroacoustic performance of poroelastic wings inspired by the silent plumage of owls

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Owls are extraordinary predators that are able to suppress their noise and achieve silent flight while attacking prey/food. The wing fringe pattern of owls is believed to contribute to their quiet flight. An understanding of the physics of the flow over owl wings may lead to noise reductions for many engineering designs, such as computer fans, propulsors, commercial airframes, and wind turbines. The principal aim of this project is to analyze a series of analytical and numerical model problems coordinated with experimental measurement to elucidate the unsteady loading and noise generation of thin fluid-loaded structures with graded poroelastic properties comparable to owl wings. This project addresses the above technical shortcomings through an interactive theoretical-experimental program that distinguishes itself in no fewer than three ways: (i) construction of analytical and numerical frameworks to predict turbulence noise generation by graded poroelastic structures, from first principles; (ii) experimental validation of acoustic scaling laws for poroelastic edges, without background flow noise; and (iii) development of a glider to measure wing noise on the fly in a manner consistent with how owls hear their self-noise. The modeling and validation efforts aim to transform a biologically-inspired noise solution into a rational paradigm for passive aerodynamic noise control in low-speed flows and to create an experimental platform for future bionic owl noise-reduction studies. This project will also include K-12 educational outreach with the DaVinci Science Center (Allentown, PA), as well as integrate undergraduate research involvement through the Lehigh Biosystems Dynamics Summer Institute (in partnership with Northampton Community College) and through a design-build-fly competition between Lehigh and Penn State.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.