Influence Of Pitching Trajectory And Airfoil Slot On Energy Capture Characteristics Of Semi-active Flapping Airfoil Generator

Wind energy,as a widely distributed clean energy,has attracted much attention of the scholars at home and abroad.The traditional rotary generator captures energy very inefficiently at low wind speed and even can’t start automatically,so it can’t be used in most areas with low wind speed.However,the flapping airfoil generator,as a new type of generator,can still maintain high efficiency of capturing energy in low wind speed.At present,the technology of the flapping airfoil generator is developing,so it is necessary to optimize the capturing energy characteristics of the flapping airfoil generator.The capturing energy characteristics of semi-active flapping airfoil were optimized from two aspects of the flapping airfoil’s pitching trajectory and the flapping airfoil slot.Based on that,a semi-active flapping airfoil generator with a new type of transmission structure was proposed.And the experiments based on the prototype were carried out.The detailed research contents of this paper are as follows:(1)Five pitching trajectories with the same quasi-steady aerodynamic characteristics were proposed,and the numerical simulation model of the semi-active flapping wing was built.In order to optimize the ability of capturing energy,the semi-active flapping airfoils with five pitching trajectories were simulated by using the finite-volume method.The results show that the semi-active flapping airfoil with sinusoidal pitching trajectories have the best capturing energy characteristics.(2)A series of flapping airfoils with symmetrical slots along the chord line were presented and applied to the semi-active flapping airfoils generator.Through numerical simulation,the influence of the airfoil slot on the energy capturing characteristics of the semi-active flapping airfoil generator was studied.And the contrast simulation experiments of the semi-active flapping airfoil with slots and without slots were carried out.The results show that the semi-active flapping airfoil with slots Angle of 10° has the best capturing energy characteristics.(3)A new semi-active flapping generator based on ratchet drive was proposed.A physical machine of semi-active flapping generator was built based on this model.And the prototype experiments were carried out to verify the numerical researches above.The results show that the numerical study and the prototype experiments are in good agreement.