Abstract
Two-dimensional numerical simulations are performed to investigate the effect of weak acoustic excitation on the separated flow over an NACA0012 airfoil with the angle of attack a = 12°, at the Mach number M = 0.1 and at the low Reynolds numbers Re = 5 × 104, 1 × 105. The pressure amplitude of the induced acoustic wave is 0.05% of the static pressure at infinity. The results show that the acoustic waves with the appropriate frequencies make the time-averaged lift coefficient higher. This effective frequency range depends on the Reynolds number and its mean value St ≅ 0.023 √Re, which agrees with the experimental results of Zaman for an LRN- (1) -1007 airfoil. In the effective frequency range, the maximum vorticity in the laminar boundary layer of the airfoil becomes larger. On the other hand, there is no difference between the results of the two Reynolds numbers in the amplitudes of the lift coefficient variation due to the same excitation.
