Oscillating-Foil Turbine Performance Improvement by the Addition of Double Gurney Flaps and Kinematics Optimization

Refinement of the performance a fully constrained oscillating-foil turbine is carried out via addition passive double Gurney flaps. Flaps ranging from hGF=0.005c to 0.075c are added at trailing edge NACA 0015 blade turbines operating in high-efficiency regimes without leading-edge vortex shedding (LEVS). Performance improvements determined using 2D numerical simulations with an unsteady Reynolds-averaged Navier–Stokes (URANS) approach. Based on recent study flaps stationary foils, instantaneous power-extraction coefficients analyzed and modifications foil’s kinematics tested order benefit flaps’ improvements. Modifications pivot point location foil, pitch-heave phase, pitching amplitude considered. Improvements found for all cases studied, including some previously optimal reported literature. The flaps, being simple device, offer great practical application potential. They represent efficient refinement already robust high-performance perceived shedding, essential characteristic actual, finite-span applications.