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Performance Analysis of Flapping Foil Flow Energy Harvester Subjected to Non-Sinusoidal Pitching Motion

Two-dimensional flow simulation study is carried out to investigate the aerodynamic performance and efficiency of Fully Active flapping foil flow energy harvesters subjected to non-sinusoidal pitching motion. The device comprises of NACA0015 airfoil mounted on a translational spring and damper system. The airfoil is subjected to nonsinusoidal pitching and sinusoidal heaving motion through external excitation. The impact of non-sinusoidal pitching motion and airfoil thickness is studied, using simulations in Ansys Fluent ®, on the performance of such energy harvesters. Airfoil motion is accommodated by allowing the use of sliding meshes. The User Defined Functions(UDFs) are used to induce airfoil and mesh motion. Heaving motion is realized by reference frame motion. Different non-sinusoidal profiles are tested and their effect of energy extraction performance is investigated. It is found that the major part of energy extraction obtained by heaving motion. The non-sinusoidal pitching motion helps improve the formation and development of leading edge vortex, synchronization of vertical force and vertical velocity by increasing the peak value of vertical force. This results in an improved energy extraction performance. The maximum power extraction efficiency of 39.12% is achieved for NACA at Re=1100 for selectively tuned parameters.