A comparison of NACA 0012 and NACA 0021 self-noise at low reynolds number

Abstract

The self-noise of NACA 0012 and NACA 0021 airfoils are recorded at a Reynolds numbers of 96,000 in an anechoic wind tunnel at an angle-of-attack range of −5◦–40◦. Results suggest that the low angle-of-attack tonal noise of the airfoils behaves differently, with the NACA 0021 producing tones at much higher anglesof-attack but not near 0◦. Noise generated at the onset of stall is subtlely different, with signature of the NACA 0012 forming over a larger angular range compared to the NACA 0021 where the stall signature forms suddenly.