二次元静止翼から発生する離散周波数騒音の研究
離散周波数騒音の能動制御
1997 年 63 巻 605 号 p. 126-131
詳細
1997 年 63 巻 605 号 p. 126-131
The active noise control of discrete tones generated in a uniform jet flow on a two-dimensional wing was investigated. Discrete tone noise is generated by a self-excited feedback loop formed by the acoustic field and the unstable boundary layer. In this work, we conducted an active control experiment using a flap driven by piezoceramic levers, which can vibrate with a phase delayed from the velocity fluctuation signal on the suction side. When the flap motion lags the pressure fluctuation at the trailing edge with a phase angle of 180 degrees, it was found that the discrete tone noise was reduced by a maximum of about 7 dB, the flow fluctuation intensities in the boundary layer on the suction side were reduced by about half, and the correlation area of the flow fluctuation at the trailing edge decreased. This confirms that discrete tone generation is caused by the feedback loop and that the discrete tone generation is actively reduced by trailing edge control.
