Influence of suction flow control on energy extraction characteristics of flapping foil

Flapping foil (FF) is a relatively new renewable energy extraction device, which has the advantages of simple structure, strong environmental adaptability and little impact on the environment. This study proposed a new FF energy extraction equipment with suction control added to the surface. Based on the moving grid technology, the effect of different suction control methods on energy extraction characteristics of FF was numerically investigated. In this paper, taking NACA0012 as the reference airfoil, the influence laws of key parameters, such as suction velocity, suction port position and suction mode on the energy extraction efficiency of FF were studied respectively. The results show that, compared with the original FF, the addition of suction control can effectively control the size of the leading edge negative effect vortex, increase the force consistent with the motion direction of the FF and its surface pressure difference, thus improving the energy extraction efficiency. In addition, the innovative change of suction mode to sinusoidal suction mode in this paper can not only enhance the stability and safety of FF operation structure, but also its energy extraction efficiency is not much different from that of FF with sudden suction control.