Title

VALIDATING THE METHOD OF PRESSURE SENSING TO OPTIMIZE FLAPPING FOIL ENERGY EXTRACTION

Date of Award

2013

Degree Type

Thesis

Degree Name

Master of Science in Ocean Engineering

Department

Ocean Engineering

First Advisor

Jason Dahl

Abstract

Renewable energy resources are in high demand due to a world-wide desire for cleaner energy production. Flapping foil tidal driven systems have begun being tested and implemented at prototype scales. These prototype systems use limited control to maximize energy production. This thesis uses biological inspiration from the sensory system in sh to enhance the eciency of these energy harnessing systems with the use of surface mounted pressure sensing. Eight pressure sensors were found to be a good balance for quantity with respect to cost and accuracy. Optimal locations around the foil were determined from application of a Random Search algorithm and a uid moment approximation. A 2-D numerical code was created to simulate a NACA0015 apping foil in uniform ow. A wide parameter space of sinusoidal heave and pitch motions was run and a database of force, pressure, and eciency values along with ow visualization was built. A maximum eciency of 0.43 was reached for the trajectory of motion with a pitch amplitude of 90, heave amplitude of 1:25 and a Strouhal number of 0.5.

A control platform dependent on pressure measurements at the eight sensor locations was created in the 2-D numerical code. By implementing basic control, motion trajectories converge to the optimal motion based on pressure comparisons around the foil to pressure traces from the motion with highest eciency. In addition, a laboratory for experimental testing and validation was set-up. The motion control system was connected and tested for a tow tank set-up. Motion programs were written for the same parameter space modeled in this thesis. Through numerical modeling, pressure sensing was found to be an eective method to enhancing the eciency of a apping foil energy extraction system.

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