音源の能動制御による軸流送風機の騒音低減の研究

抄録

To suppress the noise generated from an axial-flow fan, active control was adopted for the pressure fluctuation in the stage. The main part of noise, which oscillates at the blade passing frequency, is caused by rotor-stator interaction. Our main aim is to clarify whether the noise is controllable in principle by manipulation of the pressure fluctuation in the stage. Two types of control systems with two loudspeakers were investigated. One is the "mode replacing" method that changes the traveling mode with blade passing frequency into a damping mode in the stage. The other is the "sound absorbing" method by which the energy of pressure fluctuation is absorbed by loudspeakers. It is found that both these noise reduction systems are effective in controlling the noise.