水中を上昇する気泡による衝撃雑音発生のメカニズムについて

概要

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In this research work, it is found that the impulsive noise, accompanied by some oscillatorily damping pressure change, is generated by the ascending bubbles, which are blown into the water through a porous plate made by sintering of AS resin, and through a needle tube. This impulsive noise is detected by a small hydrophone, inserted into the ascending bubbles, and is supposed to be generated at the instant of rupture of the ascending bubbles or coagulation of them. However, the generation of the impulsive noise is not continuous, but intermittent. From our experimental results of the high-speed photography and the flash photography, the oscillatorily damping pressure change, following the impulsive noise, is concluded to be caused by the pulsative oscillation of the tiny bubbles, separated from the relatively large ascending bubbles. The frequency of the oscillatorily damping sound pressure change, following that impulsive noise, is usually the order of several kHz, but sometimes it is over than 20 kHz and included in the so-called ultrasound range. Moreover, the order of the peak to peak sound pressure amplitude of that impulsive noise is sometimes over than 100 mbar, when the air flow rate for the formation of the small air bubbles in water is high enough.
社団法人日本音響学会の論文
1981-08-01