
系統識別號 
U00021308200821030300 
中文論文名稱

微噴嘴流之研究 
英文論文名稱

Investigation of Micronozzles Flow 
校院名稱 
淡江大學 
系所名稱(中) 
機械與機電工程學系博士班 
系所名稱(英) 
Department of Mechanical and ElectroMechanical Engineering 
學年度 
96 
學期 
2 
出版年 
97 
研究生中文姓名 
許欽淳 
研究生英文姓名 
ChinChun Hsu 
學號 
893340025 
學位類別 
博士 
語文別 
英文 
口試日期 
20080724 
論文頁數 
120頁 
口試委員 
指導教授康尚文 委員楊秉純 委員楊建裕 委員楊龍杰 委員張正興 委員康尚文

中文關鍵字 
微文氏管
微噴嘴
壓損係數
壓損係數比
FLUENT

英文關鍵字 
Micro venturi
Micronozzle
Pressure loss coefficient
Ratio of pressure loss coefficient
FLUENT

學科別分類 

中文摘要 
本文主要是針對微噴嘴的空氣流場進行研究與探討，研究分為兩部分進行，分別是探討微文氏管的流力特性及曲面微噴嘴邊界對流力效能的影響，並將實驗結果與CFD軟體的分析結果相互比較，藉以觀察微文氏管內之流場分佈並探討微噴嘴較佳之流力性能。
在微文氏管的研究部分，首先利用微機電製程技術製造出兩種不同尺寸的微文氏管，寬度分別為150及200微米，開口角度各為45°，總長則為10 mm，再以空氣作為工作流體，利用不同質量流率來量測微文氏管進出口的壓力差並配合FLUENT軟體分析觀察其流場分佈的情況。結果顯示，當流量小時，此兩種不同外型的喉部出口處都會因回流的關係產生相對稱的分離渦流，但隨著流量增大，分離區會持續擴大導致渦流相互影響，此時渦流之間的吸引力造成分離區不再對稱進而使流場的分佈偏向於一邊。而在速度分佈部分，當流量為5.338 mg/min時，寬度為150微米的喉部區流速已經高於聲速，隨後因速度不斷增加，空氣黏滯力影響了速度分佈而產生了速度衝擊現象。
第二部份是討論微噴嘴的流力特性，主要是利用FLUENT軟體來分析三種不同外型的單一曲面微噴嘴/擴大器，藉由分析的結果來比較各種外型的微噴嘴/擴大器之壓損係數及壓損係數比。模擬結果顯示，微噴嘴/擴大器的壓損係數會隨著雷諾數的增加而減少，但壓損係數比反而隨著雷諾數的增加而提高。而在相同雷諾數下，擴大器的壓損係數則會低於噴嘴的壓損係數。
另外，吾人同時將文獻中之理論解和實驗數據與FLUENT之模擬值相互比較，發現曲面形貌（a= 5⁄3）之微噴嘴/擴大器有著較高的壓損係數，同時壓損係數比也比直線邊界來的高，因此結合此外型微噴嘴/擴大器之元件有較高之流體驅動力並能有效提高其效率。而模擬值與實驗值亦符合理論值，因此對於微噴嘴/擴大器的設計與應用提供了一明確的參考依據。 
英文摘要 
This study presents the investigating of microchannels flow. It is divided into two parts, the flow characteristics of micro venturi and the performance of straightwalled and curvedwalled micro nozzle/diffuser respectively. The experimental results are also compared with the simulation results whereby we can observe the flow field in micro venturi and discuss the bounder effect of micro nozzle/diffuser.
First, we adopt MEMS technology to fabricate micro venturis with different widths of 150 and 200 um respectively and utilize FLUENT software to analyze the flow fields. Air was set as the working fluid and the air mass flow rate of inlet is changed to obtain the pressure drop between inlet and outlet.
When a flow passes through the throat, the backflow results in the symmetric separations occur and grow with the increase of mass flow rate. As the separation is large enough, the suction between both separations will be larger than the resistance of flow, the larger separation will appear on one side and leads the flow to slant to the other side. The result also shows the complicated shock wave flow structure was generated by the effect of viscosity.
The second part of this paper presents a CFDsimulation of the performance of straightwalled and curvedwalled micro nozzle/diffuser by FLUENT software. Such nozzle/diffusers are mainly used in micro venturi and also applied to valveless micropumps.
The results show that the pressure loss coefficient for the micro nozzle/diffuser decreases with the Reynolds number whereas the ratio of the pressure loss coefficient increases with the Reynolds number. At the same Reynolds number, the pressure loss coefficient of micro nozzle is higher than that of the micro diffuser.
The model is also compared with different previously experimental measurements and shows a good agreement. For a fixed volumetric flow rate, the results show the curved profile bounder (a = 5/3) micro nozzle/diffuser has higher pressure loss coefficient and higher ratio of the pressure loss coefficient than that of the straight profile bounder. The theoretical analysis and design basis can then be formulated as a reference and applied to the fabrication of micro nozzle/diffuser from this study.

論文目次 
List of Contents
Acknowledgments I
Abstract(Chinese) II
Abstract(English) IV
List of Contents VI
List of Figures IX
List of Tables XVI
Nomenclature XVII
Chapter 1 Introduction 1
11 Background 1
12 Motivation and Goals 2
13 Literature Review 3
Chapter 2 Theoretical Analysis 10
21 Microchannel Flow 10
22 Governing equations 11
23 Restriction Flow Meters for Internal Flows 12
24 Compressible Fluids 13
25 Incompressible Flow in Micro Nozzle/Diffuser 16
Chapter 3 The Investigation of Micro Venturi 19
31 Introduction 19
32 Fabrication of Silicon Micro Venturi 20
33 Experiment of Micro Venturi 22
331 Error Correction of Experimental Equipment 23
332 Procedure of Experiment 23
34 Numerical Analysis 24
341 Introduction to FLUENT 24
342 Basic Theory of FLUENT 25
35 Numerical Study of Micro Venturi 27
351 Graphics Design and Mesh Generation 27
352 Boundary Condition 28
36 Results and Discussion 28
361 Experimental Results 28
362 Numerical Simulation Results 29
363 Comparison of Experiment and Simulation 31
37 Conclusions 32
Chapter 4 The Analysis of Curvedwalled Micro Nozzle/diffuser 34
41 Introduction 34
42 Numerical Study of Curvedwalled micro nozzle/diffuser 35
421 Model Construction 35
422 Boundary Condition 36
43 Result and Discussion 37
431 Results of Numerical Simulation 37
432 Analysis of Theoretical, Experimental and Simulation Results 39
433 Effects of Reynolds Numbers, Open Angle and Coefficient “a” 40
44 Conclusions 41
Chapter 5 Conclusions 43
References 46
Figures 51
Tables 100
Appendix 104
Publications 119
List of Figures
Figure 11 The fabricated micronozzle with 19 mm width of throat 51
Figure 12 Trust efficiency results for both the fluid and experimental testing for two different nozzles, (a) 34 mm throat and a 7.1:1 expansion ratio (b) 37.5 mm throat and a 16.9:1 expansion ratio 51
Figure 13 Streamline for lowRe Model 52
Figure 14 Comparison of DSMC results with NS prediction and experimental data 52
Figure 15 Illustration of fluid flow through an orifice 53
Figure 16 Discharge coefficient for compressible flow through microorifices 53
Figure 17 Manufactured meso and micro nozzles 53
Figure 18 Distribution of centerline Mach number in micro nozzles with different scales 54
Figure 19 Contours of Mach number at different outlet pressures, (a) 65 kPa; (b) 55 kPa; (c) 30 kPa 54
Figure 110 The comparison of DSMC, NC, and experimental data for mass flux vs pressure difference 55
Figure 111 The flow field at Re = 15 55
Figure 112 The flow field at Re = 45 56
Figure 113 The streamline of the flow field and the Mach number contours 56
Figure 114 The contours of nozzle discharge coefficient and the jet diameter 57
Figure 115 The valveless pump 57
Figure 116 Turbulent flux throughout a diffuser, (a) positive flow direction, (b) negative flow direction 58
Figure 117 The diagrams of diffuser efficiency ratio and volume flow rate with pump pressure 58
Figure 118 Nozzle/diffuser flow at small Re 59
Figure 119 Nozzle/diffuser flow at large Re 59
Figure 120 Influence of the Reynolds number on the pressure loss coefficient 60
Figure 121 Influence of the opening angle on the pressure loss coefficient 60
Figure 122 The variation of pressure loss coefficient in a conical diffuser, (a) fully development; (b) thin inlet boundary layer 61
Figure 123 The variation of pressure loss coefficient in a planar diffuser, (a) fully development; (b) thin inlet boundary layer 62
Figure 21 Gas flow regime with different Knudsen number 63
Figure 22 The main models with different Knudsen number 63
Figure 23 Internal flow through a generalized nozzle 64
Figure 24 Definitions of the different regions in the nozzle/diffuser element 64
Figure 25 The loss coefficient K and pressure loss coefficient ξ in different types of nozzle/diffuser 65
Figure 26 Compressible flow in an infinitesimal stream tube 65
Figure 31 The Herschel standard Venturi 66
Figure 32 The illustration of micro orifice plate 66
Figure 33 The illustration of micro venture tube 66
Figure 34 Fabrication processes of micro venture 67
Figure 35 The illustrations of two different micro venture 68
Figure 36 The arc corner of micro venturi after RIE etching 68
Figure 37 The diagram of micro venturi after dry etching 69
Figure 38 The roughness of fabricated micro venturi 69
Figure 39 The setup of experimental equipment 70
Figure 310 The sketch of micro venturi 70
Figure 311 The entity photo of micro venturi 71
Figure 312 The pressure gauge, Drunk DPI 705 71
Figure 313 The processes of FLUENT solving the program 72
Figure 314 The simulation domains of micro venturi by GAMBIT 73
Figure 315 The grid contour of micro venture 74
Figure 316 Overview of the coupled solution method 74
Figure 317 The experimental and simulation results in two different types of micro venturi 75
Figure 318 The illustration of Type I with Qm=0.767 mg/min, (a) velocity contour, (b) streamline of velocity 76
Figure 319 The flow distribution of Type I with different mass flow rate 77
Figure 320 The crosscutting line on Yaxis of velocity in Type I 78
Figure 321 Velocity magnitude profile along the crosscutting line with different mass flow rate 78
Figure 322 The velocity contour of Type I when mass flow rate is 5.338 mg/min 79
Figure 323 The diagram shows the shock occurs when mass flow rate is 8.52 mg/min 79
Figure 324 Contours of Mach number when mass flow rate is 16.472 mg/min 80
Figure 325 The asymmetry separations of Type II when mass flow rate is 8.275 mg/min 80
Figure 326 The flow distribution of Type II with different mass flow rate 81
Figure 327 The length of separation with different mass flow rate 82
Figure 328 The comparison diagram of the experimental and simulation results in Type I 83
Figure 329 The comparison diagram of the experimental and simulation results in Type II 83
Figure 41 The operation of the parallel arrangement of a doublechamber diffuser pump 84
Figure 42 Operation of the diffuserbased pump: (a) Supply mode; (b) Pump mode 84
Figure 43 The illustrations of straightwalled micro nozzle/diffuser with different open angles (a) 5°, (b) 10°, (c) 15°, (d) 20° and (e) comparison sketch 85
Figure 44 The illustrations of curvedwalled (I) micro nozzle/diffuser with different midpoint width (a) 431.2, (b) 564.5, (c) 701.9, (d) 864 m and (e) comparison sketch 86
Figure 45 The illustrations of curvedwalled (II) micro nozzle/diffuser with different parameter, a, (a) 1/1780, (b) 1/884, (c) 1/582, (d) 1/428 and (e) comparison sketch 87
Figure 46 The mesh density of straightwalled micro nozzle/diffuser 88
Figure 47 The mesh density of curvedwalled (I) micro nozzle/ diffuser 88
Figure 48 The mesh density of curvedwalled (II) micro nozzle/ diffuser 89
Figure 49 The sketch of straightwalled and curvedwalled (I) micro nozzle/diffuser ( = 20°) 89
Figure 410 The distribution of pressure loss coefficient and its ratio at different Reynolds numbers (5° and 5° SIO) 90
Figure 411 The distribution of pressure loss coefficient and its ratio at different Reynolds numbers (10° and 10° SIO) 90
Figure 412 The distribution of pressure loss coefficient and its ratio at different Reynolds numbers (15° and 15° SIO) 91
Figure 413 The distribution of pressure loss coefficient and its ratio at different Reynolds numbers (20° and 20° SIO) 91
Figure 414 The relationship between pressure loss coefficient and open angle of Model 1 when Reynolds number is 70 92
Figure 415 The relationship between pressure loss coefficient and open angle of Model 2 when Reynolds number is 70 92
Figure 416 The sketch of straightwalled and curvedwalled (II) micro nozzle/diffuser ( = 20°) 93
Figure 417 The distribution of pressure loss coefficient and its ratio at different Reynolds numbers (5° and a = 1/1780) 93
Figure 418 The distribution of pressure loss coefficient and its ratio at different Reynolds numbers (10° and a = 1/884)
Figure 419 The distribution of pressure loss coefficient and its ratio at different Reynolds numbers (15° and a = 1/582) 94
Figure 420 The distribution of pressure loss coefficient and its ratio at different Reynolds numbers (20° and a = 1/428) 95
Figure 421 The relationship between pressure loss coefficient and open angle of Model 3 when Reynolds number is 70 95
Figure 422 The relationship between pressure loss coefficient and Reynolds numbers with different results at = 10° and 20° (Mode 1, diffuser) 96
Figure 423 The relationship between pressure loss coefficient and Reynolds numbers with different results at = 10° and 20° (Mode 1, nozzle) 96
Figure 424 The relationship between pressure loss coefficient and Reynolds numbers with different results at = 10° and 20° (Mode 2, SIO diffuser) 97
Figure 425 The relationship between pressure loss coefficient and Reynolds numbers with different results at = 10° and 20° (Mode 2, SIO nozzle) 97
Figure 426 The relationship between pressure loss coefficient and open angle when Reynolds number from 300 to 1500 98
Figure 427 The relationship between pressure loss coefficient and coefficient a when Reynolds number from 300 to 1500 98
Figure 428 The diagram of the “backflow” when the open angle is 20 and Reynolds number is 1500 99
Figure 429 The diagram of the “backflow” when the coefficient a is 1/428 and Reynolds number is 1500 99
List of Tables
Table 21 The mean free path of the air with different pressure 100
Table 31 The size chart of micro venturi 100
Table 41 The description of the size of micro nozzle/diffuser 101
Table 42 The pressure loss coefficient of micro nozzle/diffuser when Re = 70 102
Table 43 The results of theoretical, experimental and simulation when Re = 70 103

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