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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/13872

Title: 高速液體噴流霧化模式的理論分析
Theoretical Analyses for the Atomization Model of High-speed Liquid Jets
Authors: 陳天任
Contributors: NTOU:Department of Mechanical and Mechatronic Engineering
國立臺灣海洋大學:機械與機電工程學系
Keywords: 高速噴流;霧化
Date: 2010
Issue Date: 2011-06-30T07:29:21Z
Abstract: 液體噴流霧化技術已經非常廣泛地應用在許多工業科技方面,尤其在各種引擎燃燒室內的燃料霧化應用,液體噴流霧化液滴、液滴速度分佈、噴流斷裂長度等皆對燃燒效率與排放汙染具有深遠的影響。儘管過去在此方面有許多實驗研究,但是液體噴流霧化現象的物理發生過程仍然無法完全地了解。目前在本研究中,有關高速液體噴流霧化模式,將以噴流表面波不穩定性分析為基礎,也就是說,氣/液體界面間的不穩定成長率分析,配合噴流隱埋法與環帶狀霧化模式,此法僅較少網格,來計算預測出液體噴流核心之流場結構,以及霧化液滴的形成。在本研究中,首先以數值方法分析高速液態噴流的表面波不穩定性,包含高速噴流速度變化、氣體/液體密度比變化、液體黏度與表面張力的變化,對於不穩定表面波成長率的影響。 在本研究中,建立噴流隱埋法的基本方程式,並且以數值方法求解,以預測同軸式噴流的內部軸向核心流場結構與在噴流表面的霧化現象。如此,有關霧化液滴的形成可以依據環帶狀霧化模式來建構,並進而預測流場速度、液滴剝離率與液滴大小分佈。最後,有關純水/空氣與JP-8燃油/空氣同軸式噴嘴的霧化經驗公式比較評估。
The technology of the liquid jet atomization has been widely used in many industrial and technical applications. In various engine combustion chambers, atomized drop size, velocity distribution, and breakup length have profound influences on the combustion efficiency and emission pollution. Despite a great quantity of past experimental studies, the physical process of atomization phenomenon has not been fully understood. In the present study, based on the jet surface wave instability analysis on the interface of liquid and gas, the atomization model for the high-speed liquid jets was established and coupled with Jet Embedding Method and an annular ligament breakup model, which needs only economic adaptive grid system. Accordingly, the liquid jet core and drop formation in the atomization process can be numerically predicted. In the present study, the surface wave instability of high-speed liquid jets was first analyzed using the numerical method, including the influences of variations of jet velocity, gas/liquid density ratio, liquid viscosity and surface tension for high-speed liquid jets on growth rates of instable waves along the liquid jet surface. In the present study, the basic equations governing the flow field using Jet Embedding Method was set up and solved to determine the formation of the liquid jet core and the atomization on the liquid jet surface. Thus, drop formation can be established according to the annular ligament breakup model to predict the flow velocity, drop breakup rate, and drop size distribution. Finally, the atomization of water/air and JP-8 fuel oil/air ejected from a coaxial injector was numerically predicted, and evaluated by comparing with the CICM empirical correlation.
URI: http://ethesys.lib.ntou.edu.tw/cdrfb3/record/#G0M97720076
http://ntour.ntou.edu.tw/ir/handle/987654321/13872
Appears in Collections:[機械與機電工程學系] 博碩士論文

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