Aerodynamic and Aeroacoustic Performance of Serrated Airfoils

The aerodynamic and aeroacoustic performance of serrated airfoils have been studied experimentally. A comprehensive aerodynamic study of a symmetric (NACA 0012) and an asymmetric (NACA 65(12)-10) airfoil with different types of trailing-edge serrations has been performed. Steady aerodynamic force measurements over a wide range of Reynolds number and angles of attack has been carried out. Results have shown that the use of trailing-edge serrations can generally lead to a significant reduction in the airfoil lift coefficient. It has also been shown that the most effective serrations, in terms of noise reduction, namely the sharp sawtooth and slotted-sawtooth, cause the highest level of lift reduction. Two-dimensional Laser Doppler Anemometry (LDA) and hotwire tests have also been carried out in order to better understand the effects of trailing-edge serrations on wake development and the energy content of the turbulent coherent structures. Results have shown that the use of trailing-edge serrations leads to significant reduction in the airfoil’s wake turbulence level, which appears to have been caused due to the interaction between flow field over the tip and root planes. Preliminary experimental results confirm that passive flow control methods, such as serrations, used for airfoil noise reduction can significantly affect the aerodynamic performance of the airfoil.<br/>