水中聲波通過氣泡幕衰減特性實驗探討

本文主要從理論及實驗上探討低頻聲波通過任意體積分率之氣泡幕衰減特性。理論部分利用Lai (1999) 與Tien (2001) 將低體積分率之計算方式推導至任意體積分率模式，並於氣泡液體之動量方程式中，加入氣泡間交互作用的影響，重新整理出適用於任意體積分率之聲波傳遞方程式，再由液體與氣泡幕間速度及壓力連續之邊界條件，求出聲波通過氣泡幕之穿透係數及反射係數。實驗的部分則著重於低頻聲波通過氣泡幕之特性研究，探討頻率為 (500 Hz ~ 90 kHz)。在微小體積分率時，本文實驗與Lai (1999) 與Tien (2001) 及傳統理論計算所得聲波通過氣泡幕之穿透及反射係數相當吻合；而在高體積分率時，本文實驗除了在較低頻部分 (500 Hz ~ 1 kHz) 因實驗儀器限制而有較大的差異外，在較高頻部分 (1 kHz ~ 90 kHz) 皆有相當不錯之一致性。

關鍵字

氣泡幕；聲波傳遞；體積分率；氣泡液體；高頻

並列摘要

The attenuation of sound propagating through a bubble screen was investigated both theoretically and experimentally in this study. The theoretical results of Lai (1999) and Tien (2001) were applied. By adding an additional virtual mass force into the momentum equation of the bubbly liquid, a modified Helmholtz equation valid for the sound propagation in the bubbly liquid at finite gas-volume fraction is reformulated. The low frequencies, (500 Hz ~ 90 kHz), of the sound was focused for studying the sound propagating through a bubbly liquid. The experimental results agree with the theory deduced by Lai (1999) and Tien (2001) and the classical theory. There are excellent agreements of experimental results and theoretical results in the higher frequency range (1 kHz ~ 90 kHz), but deviations in the lower frequency range (500 Hz ~ 1 kHz).

並列關鍵字

bubble screen ； sound propagation ； volume fraction ； the bubbly liquid ； higher frequency

國際替代計量

水中聲波通過氣泡幕衰減特性實驗探討

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