MITIGATING TONAL NOISE WITH SUCTION-BLOWING EXCITATION ON NACA0012 AIRFOIL AT LOW REYNOLDS NUMBERS

Abstract

The present study numerically investigates the impact of periodic suction-blowing excitation on the tonal noise radiated by a NACA0012 airfoil. The free-stream flow over the airfoil is prescribed at Reynolds number 5000, Mach number 0.2, and an angle of attack of 5 degrees. The present investigation uses the direct numerical simulation approach to resolve flow and sound fields. The suction excitation is applied normally to the airfoil surface near the leading edge while blowing is applied tangentially at the trailing edge. The suction excitation reduces the effective cross-sectional area while blowing enhances it, making the airfoil more streamlined. The blowing also forces vortex-shedding downward, reducing the scattering process of pressure from the trailing edge. Consequently, the lift-to-drag ratio increases 1.4 times with the application of excitation compared to the no-excitation case. The excitation decreases the amplitude of lift fluctuation, diminishing the dominant lift dipole sound source of the tonal noise. Furthermore, the disturbance pressure fields exhibit a reduction. Thus, it is observed that the intensity of tonal noise decreases significantly compared to airfoil without any excitation. This research contributes insights into the mitigation of tonal noise using the suction-blowing excitation active control method for a NACA0012 airfoil configuration. � 2024 Proceedings of the International Congress on Sound and Vibration. All rights reserved.