侧向襟翼不同运动模式对扑翼获能特性的影响

As a new type of fluid energy extraction device, the flapping foils have the characteristics of small environmental impact and high adaptability to low flow velocity conditions. In order to improve the energy extraction efficiency of the flapping foils, a movable lateral flap for the flapping foil is designed in this study. The energy extraction characteristics of flapping foils without flaps, with movable lateral flaps and with fixed lateral flaps are compared based on the numerical simulations. The mechanism of movable lateral flaps to improve the energy extraction efficiency η of the flapping foils is analyzed. Three motion patterns are designed for the movable lateral flaps and the differences in the effects of the movable lateral flaps with different motion patterns on the energy extraction performance are compared at different reduced frequencies f^∗. The results show that, the flapping foil using flaps with stationary-start pattern has the best energy extraction characteristics. It obtains the largest energy extraction efficiency η = 48.0% at f^∗ = 0.18, which is an improvement of 21.7% compared with the conventional foil. Due to the sudden change in velocity during flap motion, the flaps with sinusoidal pattern and uniform velocity pattern adversely affect the energy extraction of the flapping foils.