Enhanced performance of oscillating wing energy harvester using active controlled flap

The effects of a trailing-edge active controlled flap on the power output performance of an oscillating wing energy harvester were investigated by numerical analysis. The overset mesh technique was adopted, and a structured mesh was used to simulate multiple moving bodies in close proximity to a wall to improve the accuracy. Sinusoidal motion was applied to both the wings and flaps. The maximum pitch angles for the wing and flap were varied to determine the optimum operating conditions. Numerical results show that the attachment of a flap onto an oscillating wing deflects the incoming flow in flap's direction and increases the vertical momentum change, which consequently increases the pushing force and power. The wing and flap maximum pitch angles significantly affect the power output of the energy harvester. The maximum power output is obtained at maximum pitch angles of 70 degrees and 35 degrees for the wing and flap, respectively. The maximum power is enhanced by 11 % when the flap length is 20 % of the chord length, as compared with the optimum condition of an oscillating wing without a flap.