Aeroacoustic and aerodynamic study of trailing-edge serrated airfoils in tandem configuration

This paper presents a comprehensive experimental study on the application of trailing-edge serrations as a passive control method for reducing the aerodynamic loading on airfoils in several tandem configurations. The purpose of this study is to investigate the effectiveness of serrated trailing-edge on NACA65-710 tandem airfoil to control and regularize the turbulent flow within the gap area between the two airfoils. The wake flow characteristics for an isolated NACA65-710 airfoil with and without the trailing-edge serration treatment have been carried out using two-dimensional Particle Image Velocimetry(PIV) method. The aeroacoustic performance of the tandem airfoil configuration is also studied using in-site pressure transducers instrumented over the airfoil surface, as well as far-field microphones. To reveal the effects of trailing-edge serration on the tandem configuration, flow experiments were performed using a slotted-sawtooth serration, for several tandem configurations, with different airfoil gap distances. The results show that the use of serrations can generally lead to a significant reduction in the turbulent kinetic energy within the gap, due to the interaction between the flows issued from the tip and root of the serration. The far-field noise results have shown that a significant noise reduction can be achieved with the use of the serrations.