An Experimental Study of Rod-Airfoil Interaction Noise Mitigation With Leading-Edge Serrations

This paper presents an experimental study on rod-airfoil interaction noise and the effectiveness of the application of leading-edge serrations as a passive control method for reducing the interaction noise. A rod with 10 mm diameter and a NACA 0012 airfoil has been set up in tandem configuration, with free-stream velocity varied from 8 m/s to 32 m/s. The wake velocity profiles of the isolated rod have been first investigated by hot-wire measurements. Subsequently, a baseline NACA0012 airfoil and three different leading-edge serrated airfoils have been positioned within the wake of the rod. To better understand the aerodynamic and aeroacoustic effects of wake interaction noise, the rear airfoil, either the baseline NACA 0012 airfoil or the leading-edge serrated NACA 0012 airfoil, were equipped with pressure taps and surface pressure transducers on both sides of the chord. Far-field noise measurements and near-field hydrodynamic field have been quantified. The results show that the use of leading-edge serrations can effectively reduce the interaction noise up to 6 dB. The noise reduction is likely to be due to the breakdown of the wake turbulent structures as well as the destructive interference as a direct result of the serrations.