不同性質之穩態層流撞擊圓盤產生之液頁流場之研究

Abstract

本研究目的再深入探討存在已久的霧化技術中，衝擊式液頁流場的根本成形原則與原理。並且在引入微小液柱尺寸的新式碰撞條件下，檢視典式理論於微小尺寸之適用性。在延續Clanet [1] 研究基礎下，本文研究方法結合實驗與理論，探討在室溫室壓下，微小純水液柱或改變黏滯度之甘油水溶液，液柱噴流碰撞固體平面後所形成的液頁流場特性，試著從其所顯示的各式物理現象，探討出可能的物理原則，改變碰撞平面直徑和流體性質與其區別並探討。探討主題主要可分成三個部分：(i) 微型尺寸與理論之比較，(ii) 改變黏滯度對流場之影響，(iii) 改變噴嘴及碰撞平面直徑比之影響。 結果顯示(1) 本文使用之微型尺寸與理論有些許的差距但是整體趨勢相同；(2)改變黏滯度後，在微小尺度下水鐘輪廓及液頁流場有明顯的改變；(3)噴嘴與碰撞平面直徑比會影響液頁成形的能量。

The objective of this investigation is to study the principle of classic atomization engineering of the impinging type of liquid sheet in great depth, and the attempts would be made to introduce the collide condition of new form in micro scale of liquid jets. This investigation continues Clanet’s study [1]; combine experimental and theoretical investigations of liquid sheets generated by water jet impact on solid discs and the atomization condition of liquid sheets in atmosphere environment. The main work is divided into three parts: (i) the feasibility of classic theory applied to micrometer scale water jets, (ii) the effect of viscosity, (iii) the effect of the diameter ratio of jets and discs. The results reveal that: (1) the classical theory of formation of water bells can be applied at the micrometer scale but with acceptable error, (2) the effect of viscosity is an important characteristic in determining the shapes of water bells at the micrometer scale, and (3) the diameter ratio of jets and discs affects the energy of formation of liquid sheets.