流體與材料性質對液滴碰撞液膜影響之研究

Fluid properties and material effects on droplet-film collision

洪諄宇(Chun-Yu Hung)

指導教授 ： 潘國隆

國立臺灣大學/工學院/機械工程學研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.01671

摘要

液滴碰撞液膜的現象，按照碰撞速度的增加，可依序分類為下列五種：吸收、中心噴流、單顆二次液滴、多顆二次液滴與閉合皇冠。碰撞液滴的閉合皇冠特徵常伴隨著氣泡捲入液膜的現象。特徵現象轉變圖的繪製係根據液膜的厚度及碰撞韋伯數來描述，並定義四個濺起門檻將五種現象加以分隔。無論溶液的黏滯力或表面張力改變與否，濺起門檻皆呈現一半島型的共同趨勢。飛濺現象會因為流體黏滯力的提高而被延遲，或因為流體表面張力的降低而提前發生。此外，本實驗中所使用置於液膜下的固體撞擊平板為一壓克力板及一鋁板，發現金屬表面較容易傳遞動量而造成濺起門檻的臨界點上升及延後。

關鍵字

液滴碰撞 ； 極薄液膜 ； 高速液滴

並列摘要

An investigation in droplet-film collision is experimentally conducted. The phenomena of a drop impinging upon a liquid layer are categorized into five characteristics including absorption, central jet, secondary droplet, multiple droplets, and closed crown. Four regime thresholds are defined to segregate these five characteristics. By changing the viscosity and the surface tension of the fluids, a peninsular trend is summarized, which describes the behaviour of these specific thresholds. The sheeting-splashing threshold is postponed when the viscosity of the fluid is increased, and is advanced if the surface tension of the solution is decreased. Moreover, the material effect on the droplet-film collision is discussed. The turning point of each threshold arises with higher Weber number when the aluminum plate is replaced for the acrylic plate.

並列關鍵字

droplet collision ； thin liquid film ； high-speed droplet

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