This paper reports an experimental investigation on the application of serrations as a passive control method for reducing the aerodynamic sound from airfoils in tandem. The aim of the study is to investigate the efficiency of serrated trailing edge on cambered NACA 65-710 tandem airfoil to control and regularize the turbulence flow within the gap between the two airfoils. The wake flow characteristics for a cambered NACA 65-710 airfoil with and without the serration treatment have been quantified using two-dimensional Particle Image Velocimetry (PIV). The surface pressure coefficient distributions and surface pressure fluctuations have been measured using the pressure taps and the remote sensing probe techniques. The results show that the use of serrations at relatively high angles of attack (10 and 15 degree), can lead to a significant reduction of turbulent kinetic energy, which is believed to be due to the interaction between the flow field at the tip and root of the serrations. To better understand the aerodynamic and aeroacoustic effects of serrations on the tandem configuration, the rear airfoil was equipped with several pressure taps and surface pressure transducers. Experiments were performed using a sharp sawtooth serration, for a number of tandem configurations, with different horizontal and vertical airfoil separation distances. Results have shown that a significant reduction of surface pressure fluctuation can be achieved over the leading-edge area of the rear airfoil, particularly for configurations with larger gap distance. The wake and surface pressure results have confirmed that the use of serrated trailing edges can lead to robust control of the wake flow, and reduction of wake interaction noise.
|Name||Proceedings of the International Congress on Sound and Vibration|
|Publisher||International Institute of Acoustics and Vibration|