Experimental and Numerical Investigation of Bio-Inspired Airfoil Trailing-Edge Designs for Noise Reduction

Embedded Large Eddy Simulations (ELES) are employed in tandem with the Ffowcs Williams-Hawkings (FW-H) aeroacoustic model to investigate the aerodynamics and tonal noise of NACA0012 airfoils having different bio-inspired noise-suppressing trailing-edge (TE) configurations. Various designs, such as standard sawtooth serrations, surface finlets, finned serrations and slanted-root sawtooth serrations are studied and compared. The different designs are shown to leverage different noise-suppressing flow mechanisms. The effects of changing standard serration amplitude and wavelength on the radiated tonal peak is studied. Experimental results suggest that noise reduction for surface finlets is dependent on the airfoil angle of attack. Slanted-root serrations are shown to alter the flow-field and suppress unwanted tonal peaks. ELES results are compared with experimental measurements, with good overall agreement. ELES is demonstrated to be a reasonable alternative to the currently-used more computationally demanding, full LES or direct numerical simulation approaches.