微藥量水下爆炸氣泡在不同邊界附近行為之試驗研究

The Experimental Studies on the Behaviors of Bubble near Different Boundaries Subjected to Mini-Charge Underwater Explosions

水下爆炸有震波與氣泡兩個主要現象，當氣泡附近存在邊界時，氣泡的變化行為快速猛然複雜。水中結構物受震波與氣泡的綜合影響，能產生極大的損害。本文旨在瞭解氣泡漲縮與運動行為，以使船艦設計者能夠設計出減低甚至承受氣泡損害的結構。一般水中結構形狀複雜。因此先從氣泡在簡單平面邊界的行為研究開始。另一方面，由於爆炸氣泡文獻稀少，爆炸氣泡的行為在巨觀上與空化氣泡相似，相關研究多參考液體空化之研究成果；然而卻少有定量的研究，能證明兩者相似，作者希望能以試驗結果驗證兩者的相似程度，以便能有效運用參考現有資料。本文試驗以雷管為爆源，在爆點附近布置不同性質平板，觀察氣泡受邊界影響的行為。分析試驗結果發現，間距與邊界性質能夠影響氣泡週期、趨移方向、趨移時間與氣泡形狀，與模擬空化氣泡的理論值亦有相似之處。 Underwater explosion has two major phenomena, shock and bubble, When a boundary is presented near bubble, bubble behaviors will be fast, violent and complex. If marine structures were subjected to the combine influences of shock and bubble, a serious damage can happed. Authors wish to understand the inside of bubble behaviors, which can help designer to create more sustainable design, But the shapes of marine structure are usually complex, so authors' study begins from simple plane boundary. On the other hand, because bubble papers are rate, and cavitation bubble behaviors are similar to explosion bubble macroscopically, many researches use papers of electric shock or laser induced bubble, which are used in cavitation study, as references. Since no quantitative proof can certify their similarity, authors also wish to use experimental data to prove theirs similarity. In this paper, a detonator is exploded near different plate or boundary. High speed photograph is used to record bubble behaviors. From the analysis results author find bubble period, migration and shapes can be influenced by boundary mass, stiffness and stand-off. These behaviors also have same tendency to theoretical values of cavitation bubble.