An Experimental Investigation Into Trailing-Edge Broadband Noise Reduction Using Ogee Serrations

Trailing edge (TE) serrations have been widely used as an effective technique to reduce the turbulent boundary-layer TE noise. In this paper, an experimental campaign is carried out to study the effects of ogee serrations on TE noise reduction. Serrations are installed on a NACA 0012 airfoil and tested in an aeroacoustic wind tunnel. Ogee serrations of various geometries are retrofitted to the airfoil and tested at various flow velocities and angles of attack (AoAs). The geometry of ogee serrations is parametrized by varying serration wavelength (��) and amplitude (2ℎ). A sensitivity analysis of TE noise reduction is conducted by varying each geometric parameter of serrations. Results show that ogee serrations achieve effective noise reduction of 1-3 dB under various flow velocities. With the increase of AoA, the noise reduction gradually diminishes until noise increase occurs at AoA ≥ 15◦. Among the three geometric parameters varied in the experiments, the amplitude (2ℎ) plays a more important role than the wavelength (��) and aspect ratio (2ℎ/��).