Performance of Airfoil Plunging Using Sinusoidal Waves Superposition

This paper aims to study the aerodynamic and propulsive performance of a plunging airfoil using novel plunging waveform, that creates additional trailing edge vortices, that affects the flow field and, consequently, the aerodynamic loads on the airfoil. This waveform is generated by means of superpositioning of the regular sinusoidal wave with a faster one. This novel waveform not only allows to add another pair of trailing edge vortices but also to control their strength. It is found that as the weight of the faster wave increases, the thrust coefficient increases rapidly while the propulsive efficiency decreases slowly, allowing a window of high thrust with small efficiency reduction. Understanding the effect of generating additional trailing edge vortices within the regular flapping cycle on the propulsive performance is the main objective of this work.