An Analysis on the Flow Field Structures and the Aerodynamic Noise of Airfoils with Serrated Trailing Edges Based on Embedded Large Eddy Flow Simulations

This paper presents the numerical analysis on the aerodynamic flows and noise of airfoils with serrated trailing edges at 5 =1.6 10 Re  . Flow simulations were performed with an embedded large eddy simulation (ELES) method. Two modified airfoils with serrated trailing edges (same widths, different lengths) were studied and compared with the baseline airfoil baseline NACA-0018 airfoil. It is seen that the unsteady lift and drag coefficients of the baseline airfoil A0 have a peak at about 2270Hz, which is close to the tonal noise frequency experimentally observed. Under the flow conditions studied in this research, the longer saw tooth serrations changed the flow fields near the trailing edge, which provides the potential of suppressing the tonal noise. Predictions based on acoustic analogy indicate that the longer saw tooth serrations decreases the overall sound pressure levels. This paper provides a basic understanding of the noise reduction mechanism in the airfoils with serrated trailing edges.