On the Reductions of Airfoil Broadband Noise through Sinusoidal Trailing-Edge Serrations

The present study investigates the efficacy of sinusoidal trailing-edge (TE) serrations as a passive means for reductions airfoil broadband noise, theoretically and experimentally. Comprehensive parametric studies were conducted to determine effect serration amplitudes wavelengths on noise reduction performance National Advisory Committee Aeronautics (NACA) airfoil. Initially, paper shows use (TNO) model accurate predictions surface pressure spectrum near TE hence far-field using Wiener-Hopf method. predicted spectra levels showed good agreement with measurements wide range frequencies. reveals that local maximums overall occur when transverse turbulence integral length scale is either 1.2 or 0.2 times wavelength, which corresponds ?/?t=0.833 5, where ? ?t are wavelength scale. One key findings at highest acoustic emissions vary inversely modified Strouhal number Sthm [i.e., wsste(?)/wbl(?)?1/Sthm] narrow (i.e., small wavelengths) wider large wavelengths), wsste wbl radiated from serrated baseline airfoils. Further, also observed reduce leading-edge (LE) along self-noise, indicates in reducing total noise.