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研究生： 王修哲
Wang, Hsiu-Che
論文名稱： 同質與異質衝擊式注油器霧化特性研究
Study on Atomization Characteristics of Like- and Unlike-Doublet Impinging Jets
指導教授： 賴維祥
Lai, Wei-Hsiang
學位類別： 碩士
Master
系所名稱： 工學院 - 航空太空工程學系
Department of Aeronautics & Astronautics
論文出版年： 2002
畢業學年度： 90
語文別： 英文
論文頁數： 121
中文關鍵詞： 噴霧型樣 、密度比 、偏斜角度 、平均粒徑 、同質與 異質衝擊式注油器 、黏滯係數
外文關鍵詞： flow pattern, SMD, deviation angle, viscosity, density ratio, like-doublet and unlike-doublet impinging jet in
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    • 本研究同時探討同質與異質衝擊式注油器之特性，包括衝擊液膜型樣、霧化液滴特性、衝擊液膜偏斜角度、質通量分布和質量分布特性。
    對於衝擊液膜而言，不論是同質衝擊液膜或是異質衝擊液膜皆深受工作流體之液體物理性質影響。對同質衝擊液膜而言，當工作流體之黏滯係數小於2.1 cp (22℃)時，衝擊液膜之種類與水之同質衝擊液膜種類一樣。當黏滯係數增加至6.6 cp (22℃)時，則產生了週期掉落模式。此外，異質衝擊液膜與fluid 3所形成之同質衝擊液膜種類極為相似。此外，由衝擊液膜之液膜長度與寬度比值顯示，同質與異質衝擊液膜之形狀並不是等比例放大，而是呈現不規則形狀，顯示著衝擊液膜之不穩定性。
    在霧化液滴特性方面，異質噴流之密度比對於霧化液滴平均粒徑大小有著明顯影響。以不同比例之糖水為主題發現，具有較高密度比之異質噴流會在噴流速度較低時，衝擊霧化出較小之液滴平均粒徑。整體而言。霧化液滴之平均粒徑隨著噴流速度之增加而遞減，遞減之趨勢與以水為工作流體之同質衝擊霧化液滴一樣，亦即霧化液滴平均粒徑在低噴流速度時，呈現快速遞減趨勢，在高噴流速度時，則呈現緩慢遞減趨勢。在霧化液滴於液膜方向(側向方向)之分佈方面顯示，除水-fluid 5之組合外，其餘異質衝擊霧化液滴之分佈皆成對稱性分佈。
    在衝擊液膜偏斜角度方面，水-水和水-fluid 5之混合比對於衝擊液膜偏斜角呈現不同程度之影響。V型衝擊液膜之產生造成實驗數據與理論數據之差異。
    質通量(mass flux)隨著噴流速度之增加而增加。當量測平面愈往下遠離衝擊點時，衝擊點正下方之質通量亦隨之遞減，同樣之遞減趨勢亦產生於沿著液膜之方向。
    對質量分佈而言，大部分質量分佈於平行衝擊液膜方向，少部分分佈於垂直衝擊液膜方向。對於量測平面距離衝擊點下方98公厘和120公厘而言，噴流速度增加伴隨著擴大之垂直液膜方向和平行液膜方向質量分佈，主要是因為空氣擾流所致。此外，以質量比例觀之，隨著量測平面與衝擊點之距離增長，在衝擊點正下方呈現質量比率遞減之趨勢。

    In this research, both like- and unlike-doublet impinging jets are studied in flow pattern, mean drop size, deviation angle effect, mass and mass flux distribution.
    For flow patterns generated by like- and unlike-doublet impinging jets, viscosity of working fluids has great influence on flow patterns. For like-doublet impinging jets, as viscosity of working fluid is below 2.1 cp ( 22℃), flow patterns are similar to those presented by Lai et a[26-27]l. For viscosity of working fluid up to 6.6 cp (22℃), periodic drops mode appeals. For unlike-doublet impinging jets, flow patterns are similar to those generated by like-doublet impinging jets of fluid 3. L/W of flow patterns generated by like- and unlike-doublet impinging jets show the change of shape in liquid sheet in length as well as in width.
    Density ratios have obvious effect on mean drop size, i.e. SMD. Jets with higher density ratio obtain smaller mean drop size during at smaller velocity. Variations of SMD with mean jet velocity of solution also display similar trend as those of like-doublet impinging water jets, i.e. SMD decrease sharply at low jet velocities, while gently at high jet velocities.
    Mixture ratio effect on deviation angles reveals different results for water/water and water/fluid 5 jets. The occurrence of V-type liquid fan pattern greatly causes the difference between theoretical and experimental deviation angle of sheets.
    Mass flux increases with increase of mean jet velocities. The longer the distance below impingement point is, the lower the mass flux at position just below impingement point is. The difference in distribution of mass flux at lateral position decrease with enlarged distance below impingement point as well.
    For mass distribution, most of mass distributes at lateral plane perpendicular to that formed by pair of jets, while the growth of mass fraction in front direction is rarely. Increase in mean water jet velocity widens mass distribution in both front and lateral directions, and causes the dispersion of sprays. Besides, increasing height will decreases mass fraction at position downstream of impingement point.

    CONTENTS Abstract Chinese Abstract I Contents i List of Tables iii List of Figures iv Chapter I Introduction 1 Chapter II Literature Review and Motivation 5 2.1 Literature Review 5 2.1.1 Flow Patterns 5 2.1.2 The Sheet 7 2.2 Motivation 13 2.2.1 Observation on Flow Patterns 14 2.2.2 Characteristics of Mean Drop Size 14 2.2.3 Deviation Angle of Liquid Sheet 14 2.2.4 Mass and Mass flux Distribution 15 Chapter III Experimental Facilities and Methods 16 3.1 Injector Element Subsystem 16 3.2 Fluid Supply Subsystem 16 3.3 Photographic Acquisition Subsystem 18 3.4 Traveersing Subsystem 19 3.5 Atomized Drop Measurement Subsystem 19 3.6 Patternator 20 Chapter IV Results and Discussions 21 4.1 Properties of Working Fluids 21 4.2 Categories of Formed Flow Patterns 21 4.2.1 Flow Patterns Generated by Like-Doublet Impinging Jets 21 4.2.2 Flow Patterns Generated by Unlike-Doublet Impinging Jets 23 4.3 L/W of Formed Liquid Sheets 24 4.3.1 L/W of Flow Patterns Formed by Like-Doublet Impinging Jets 24 4.3.2 L/W of Flow Patterns Formed by Unlike-Doublet Impinging Jets 25 4.4 Mean Drop Size 25 4.4.1 SMD at Centerline of Formed Liquid Sheet 26 4.4.2 SMD Distribution Profile at Designated Condition 27 4.5 Mixture Ratio Effect on Deviation Angle of Formed Liquid Sheet 28 4.5.1 Deviation Angle Formed by Water/Water Impinging Jets 29 4.5.2 Deviation Angle Formed by Fluid 5/Water Impinging Jets 30 4.5.3 Comparison of Theoretical and Experimental Deviation Angles 31 4.6 Mass Distribution of Fluid 5/Water Impinging Jets 36 4.6.1 Mass Flux Affected by Mean Jet Velocities 36 4.6.2 Mass Distribution Affected by Mean Jet Velocities 37 Chapter V Conclusions 39 Chapter VI Future Works 42 References 44 Tables 47 Figures 63 Vita 100 List of Tables Table 1-1 Physical properties of concentrated hydrogen peroxides 47 Table 2-1 Experimental Parameters 48 Table 3-1 Properties of Working Fluids 49 Table 3-2 Specifications of model AV-250VAC Viscometer 50 a. Meter specification 50 b. Sensor specification 50 Table 4-1 SMD generated by water/fluid 2 51 Table 4-2 SMD generated by water/fluid 3 53 Table 4-3 SMD generated by water/fluid 5 55 Table 4-4 SMD generated by water/water 57 Table 4-5 Relative data for sequential variation in deviation angle of formed liquid sheet at Vj,w=6 m/s. (like-doublet impinging jet) 59 Table 4-6 Relative data for sequential variation in deviation angle of formed liquid sheet at Vj,w=9 m/s. (unlike-doublet impinging jets) 60 Table 5-1 Flow patterns of like-doublet impinging jets 61 Table 5-2 Flow patterns of unlike-doublet impinging jets 62 List of Figures Fig. 3-1 Schematic of experimental facilities 63 Fig. 3-2 Configuration of AV-250VAC Viscometer 64 Fig. 3-3 Calibrated curve of turbine flow meter 65 Fig. 3-4 Configuration of Patternator 66 Fig. 4-1a Variation in density of concentrated water-sucrose solution 67 Fig. 4-1b Viscosity change of concentrated water-sucrose solution at 22℃ 67 Fig. 4-2 Schematic illustration of impinging jets 68 Fig. 4-3 Sequential flow patterns generated by fluid 1 69 Fig. 4-4 Sequential flow patterns generated by fluid 2 70 Fig. 4-5 Sequential flow patterns generated by fluid 3 71 Fig. 4-6 Sequential flow patterns generated by fluid 4 72 Fig. 4-7 Summarized flow pattern modes generated by like-doublet impinging jets 73 Fig. 4-8 Sequential flow patterns generated by unlike-doublet water and fluid 5 jets 74 Fig. 4-9 Length-to-width ratio of liquid sheet formed by like-doublet impinging jets 75 Fig. 4-10 Length-to-width ratio of liquid sheet formed by unlike-doublet impinging jets 75 Fig. 4-11 SMD of unlike-doublet impinging jets at 6.8 cm below impingement point. (viewpoint of mean jet velocity of water) 76 Fig. 4-12 SMD of unlike-doublet impinging jets at 6.8 cm below impingement point. (viewpoint of mean jet velocity of solution) 76 Fig. 4-13 SMD of unlike-doublet impinging jets at 6.8 cm below impingement point. (viewpoint of Re of solution) 77 Fig. 4-14 Lateral distribution of SMD atomized by water-water impinging jets 77 Fig. 4-15 Lateral distribution of SMD atomized by water-fluid 1 impinging jets 78 Fig. 4-16 Lateral distribution of SMD atomized by water-fluid 3 impinging jets 78 Fig. 4-17 Lateral distribution of SMD atomized by water-fluid 5 impinging jets 79 Fig. 4-18 Comparison of SMD atomized by pairs of impinging jets at Vj,w = 4.0 m/s ..79 Fig. 4-19 Comparison of SMD atomized by pairs of impinging jets at Vj,w = 5.0 m/s 80 Fig. 4-20 Comparison of SMD atomized by pairs of impinging jets at Vj,w = 6.0 m/s 80 Fig. 4-21 Comparison of SMD atomized by pairs of impinging jets at Vj,w = 7.0 m/s 81 Fig. 4-22 Comparison of SMD atomized by pairs of impinging jets at Vj,w = 8.0 m/s 81 Fig. 4-23 Schematic illustration of momentum balance at impingement point 82 Fig. 4-24 Schematic illustration of simulating impinging angle 82 Fig. 4-25 Sequential variation in deviation angle of formed liquid sheet 83 Fig. 4-26 V-type liquid fan pattern produce at 2.4 mixture ratio by water/water impinging jets (Vo/Vf =Vj,w /Vj,w = 12.02/5.9) 84 Fig. 4-27 Effect of mixture ratio of pair of water jets on deviation angle 84 Fig. 4-28 Mixture ratio is 0.586 (Vo/Vf =Vj,w /Vj,w = 5.33/9.1) 85 Fig. 4-29 Sequential variation in deviation angle of formed liquid sheet 86 Fig. 4-30 Effect of mixture ratio of fluid 5/water jets on deviation angle 87 Fig. 4-31 Deviation angle comparison at Vj,w=2.0 m/s 87 Fig. 4-32 Deviation angle comparison at Vj,w=3.0 m/s 88 Fig. 4-33 Deviation angle comparison at Vj,w=4.0 m/s 88 Fig. 4-34 First occurrence of V-type liquid fan pattern at Vj,w=4.0 m/s 89 Fig. 4-35 Deviation angle comparison at Vj,w=5.0 m/s 89 Fig. 4-36 Deviation angle comparison at Vj,w=6.0 m/s 90 Fig. 4-37 Deviation angle comparison at Vj,w=7.0 m/s 90 Fig. 4-38 Deviation angle comparison at Vj,w=8.0 m/s 91 Fig. 4-39 Deviation angle comparison at Vj,w=9.0 m/s 91 Fig. 4-40 Deviation angle comparison at Vj,w=10.0 m/s 92 Fig. 4-41 Deviation angle comparison at Vj,w=11.0 m/s 92 Fig. 4-42 Deviation angle comparison at Vj,w=12.0 m/s 93 Fig. 4-43 Deviation angle comparison at Vj,w=13.0 m/s 93 Fig. 4-44 Deviation angle comparison at Vj,w=14.0 m/s 94 Fig. 4-45 Deviation angle comparison at Vj,w=15.0 m/s 94 Fig. 4-46 Mass flux of unlike-doublet impinging jets at spatial plane 98 mm below impingement point 95 Fig. 4-47 Mass flux of unlike-doublet impinging jets at spatial plane 120 mm below impingement point 95 Fig. 4-48 Mass distribution for Vj,w=3.95 (Rew=1974) at spatial plane 78 mm below impingement point 96 Fig. 4-49 Mass distribution for Vj,w=8.95 (Rew=4473) at spatial plane 78 mm below impingement point 96 Fig. 4-50 Mass distribution at spatial plane 98 mm below impingement point 97 Fig. 4-51 Mass distribution at spatial plane 120 mm below impingement point 98 Fig. 4-52 Variation in mass fraction with history of Rew and Refluid 5 99 NOMENCLATURE orifice area of injector area of test tube diameter of drilled orifice on injector focus of optical lens h distance between impingement and spatial plane h0 initial thickness of liquid sheet he thickness of periphery of liquid sheet ht thickness of liquid sheet L length of liquid sheet depth of orifice on injector mass flux mass flow rate of working fluid mass flow rate of oxidizer mass flow rate of fuel volume flow rate of working fluid radius of orifice on injector breakup radius between impingement point and periphery of liquid sheet in radial direction s density ratio of gas and liquid velocity on surface of liquid sheet mean jet velocity of oxidizer mean jet velocity of fuel W width of liquid sheet Re Reynolds Number SMD Sauter Mean Diameter We Weber Number Greek Symbols the highest growth rate of wavelength on liquid sheet highest growth rate coefficient of wavelengths on liquid sheet δ deviation angle θ half impinging angle θo included angle of oxidizer jet with chamber axis θf included angle of fuel jet with chamber axis μ viscosity of working fluid σ surface tension of working fluid density of surrounding air density of working fluid azimuthal angle on liquid sheet

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