Experimental Investigation of the Aeroacoustic Characteristics of an Oscillating NACA 65–410 Airfoil

This study experimentally investigates a NACA 65-410 cambered airfoil undergoing oscillating pitching motions at a chord-based Reynolds number of Re_c=4.2x10^5. Two reduced frequencies, k_r=0.023 and k_r=0.052, were tested. Results show that increasing the oscillation amplitude and frequency leads to higher far-field noise. Surface pressure fluctuations are generally comparable or higher in the oscillating cases compared to static case, except in deep stall where the static cases showed stronger fluctuations. Short-time Fourier analysis reveal significant differences between dynamic and static cases, with distinct flow regimes (R1-R4) emerging around stall onset and flow reattachment. These regimes found to be a function of k_r, mean angle of attack, and oscillation amplitude. The dynamic stall found to be a low frequency (f<1000 Hz) phenomena with intensified acoustic behavior at angles close to static stall.