抄録
In order to control the aerodynamic tonal noise from rearview mirrors, an active flow control techniques were tested in a wind tunnel experiment. Since the aerodynamic tonal noise of rearview mirror was generated by a small perturbation caused by a small step on a surface of backward-facing step or rearview mirrors, synthetic jet was introduced to break it. The experimental results showed that the noise reduction level depended on the frequency and intensity of the synthetic jet. The noise reduction level was about 6dB at synthetic jet frequency was almost the half of the frequency of the tonal noise. The amplitude of the jet velocity was only 0.2 m/s, it was quite small compare to the uniform velocity. It revealed that the synthetic jets effectively reduced aerodynamic tonal noise with small amount of energy.
