PERPUSTAKAAN UTHM

1111\111111111\1111111111\111111111111111111111111111111111111111111111111111111 *30000001957537*

,_; ! "1- '-

Il I{ (, I ...

J I

~1 \

...,

n m rn u t IlOan t I Ini

D till

D 11-/ 11\1

c:::J I If \(0( 11 ' I{JI \1

----(l-A-~-r-I -.--------\1.1111.11 III 'P

1.ln h

•

"

I

n

ZII':

"I hereby declare that I have read this thesis and in my opinion

this thesis is sufficient in terms of scope and quality for

the award of the degree of Master of Engineering (Mechanical)"

Signature

Name of Supervisor

Date

Prof. Ir 1\zhar Abdul Aziz

..... .0. .. : .. ? .. ~ .. ?!!:!L ........ .

BAHAGIAN A - Pengesahan Kerjasama*

Adalah disahkan bahawa projek penyelidikan tesis ini telah dilaksanakan melalui kerjasama antara __________ dengan _________ _

Disahkan oleh:

Tandatangan

Nama

Jawatan (Cop rasmi)

* Jika penyediaan tesis/projek melibatkan kerjasama.

Tarikh:

BAHAGIAN B - Untuk Kegunaan Pejabat Fakulti Kejuruteraan Mekanikal

Tesis ini telah diperiksa dan diakui oleh:

Nama dan Alamat Pemeriksa Luar

Dr. Victor Chelliah Technical Advisor Blok K, PSSS Lots 3288 & 3289, Off Jalan Ayer Hitam Kawasan Perindustrian Bangi

Nama dan Alamat Pemeriksa Dalam I

Pemeriksa Dalam II (Tiada)

Nama Penyelia lain (jika ada)

43000 Kajang Selangor

Dr. Jamaluddin bin Md Sheriff Jabatan Termo Bendalir Fakulti Kejuruteraan Mekanikal UTM, Skudai

Disahkan oleh Timbalan Pendafta di Fakulti Kejuruteraan Mekanikal:

Tandatangan: ......................... r0. ........................................... . Tarikh:

Nama MOHAMED TA UDDIN BIN OSMAN ····················· .. 1······· .. ··· .. ···················.

DEVELOPMENT OF A DIRECT FUEL INJECTOR FOR

A TWO-STROKE GASOLINE ENGINE

MAS FAWZI BIN MOHD ALI

A thesis submitted in fulfillment of the

requirements for the award of the degree of

Master of Engineering (Mechanical)

Faculty of Mechanical Engineering

Universiti Teknologi Malaysia

FEBRUARY 2007

11

DECLARATION

I declare that this thesis entitled "Development of a Direct Fllel Injector for a Two-

stroke Gasoline Engine" is the result of my own research except as cited in the

references. The thesis has not been accepted for any degree and is not concurrently

submitted in candidature of any other degree .

Signature .... ~ .......... . Ma~l~~~'i'JMohd Ali Name

Date

DEDICATION

To my beloved family, friends

and to all mankind.

III

i\'

ACKNOWLEDGEMENT

Alhamdulillah - praise to God for everything. I would like to extend my acknowledgement to all the beings involved either directly or indirectly in completing this work, whether your name mentioned or (unintentionally) not mentioned in the following list: All my family members especially my father Mohd Ali Shawal and late mother Salmah Bahreim, my wife Noorhayati Santuso, my children: Zakwan, Hassif and Batrisyia, my siblings: Izuddin, Shahril and NurfaraIiyana; my outstanding supervisor: Prof. Ir. Dr. Azhar Abdul Aziz; my sponsors: lPA and UTHM; helps and supports from UTHM especially Prof. Ir. Mohd Zainal Md Yusof, Assoc. Prof. Haji Mokhtar Yusoff, Assoc. Prof. Ir. Dr. Saparudin Ariffin, En. Adnan Husain, En. Erdi Ayob, En. Azreen Md Amin and En. Syafci Samsir; brilliant advices from Prof. Amer Nordin Darus, Assoc. Prof. Dr. lamaluddin Md Sheriff, Assoc. Prof. Dr. Sanjayan Velautham, Dr. Zulkarnain Abdul Latif, Tn. Hj. Sairaji Suhadi; continuous support from Automotive Lab personnel: Dr. Mohd Shuisma Mohd Ismail, En. Subki Shamsuddin, En. Hishamudin Mohd lamil, En. Wan Maizan, En. Sadid, En. Samsuri; Aeronautic Lab: Assoc. Prof. Dr. Mohammad Nazri Mohd laafar, En. Basid, En. lohari Haron; Material Science Lab: Dr. Astuty Amrin, En. Azri Samian; Metrology Lab: En. Khalid Shukhairi; Machine Shop Lab: En. Abd. Rased Majid; Thern10 Lab: En. Mohd. Hanafi Long; Fluid Lab: En. Mohd Rafi Bachor @ Mohd Yasin; Electrical Power Lab: En. Yusof; Central Store: En. Ayob Mohd Said; fellow researchers: En. Mazlan Said, En. Ariffanan, Mr. Ng Tee Neng, Mr. Fong Kok Weng, En. Mohd Farid Muhamad Said, En. Mohamad Afiq Awang, En. Nuruddin, En. Vanebula Eka, Dr. Chrysakkis (France), Mr. Lawrence, Mr. Yahia (Aero); undergraduate colleagues: En. Hissham, En. Syamrin, Mr. Chang, En. Mohsin: the good vendors: En. Fadli (AZMA), Mr. Tan (TSPE), Mr. Khoo (TSPE), En. Bahtiar (SVT), Mr. Cheng (SVT), En. laafar (RZK); FKM: Pn. Norah, En. Redzuan; and all the authors cited in the reference section. Thank you for your contribution in making this study a success.

ABSTRACT

A prototype pressure-swirl injector was designed to suit an arbitrary two­

stroke, gasoline direct injection engine requirement. A commercial computational

fluid dynamics software FLUENT was used as a tool to analyze the performance of

the conceptual design. A prototype injector was fabricated once the conceptual

design met the requirements. The fabricated prototype injector was then subjected to

a series of specification tests such as leak test, static flow rate test and discharge

coefficient test. A dedicated test rig was set up to evaluate the performance of the

prototype injector. The spray images at specified time frame were illuminated by

Nd:Y AG laser sheet and captured using a high-speed digital camera. The stored

images were analyzed to give data of spray angle, and droplet Sauter mean diameter

at fuel-air pressure differential ranging from 1.0 to 5.0 MPa, with a step size of 1.0

MPa. From the tests, the prototype injector static flow rate, half spray cone angle

and the droplet Sauter mean diameter at fuel injection pressure of 5.0 MPa was found

to comply with the outlined requirements, which are approximately 475 cc/min, 32°

and 19 11m respectively. Finally, the experimental data was compared with the

calculated data. It was found that the measured data of static flow rate, discharge

coefficient, and droplet Sauter mean diameter were higher than the computed data at

fuel-air pressure differential between 1.0 and 3.0 MPa. In contrast, the calculated

initial spray angle was overestimated by 3% at all tested fuel-air pressure

differentials.

vi

ABSTRAK

Sebuah prototaip penyuntik tekanan-pusaran telah direkacipta untuk mencpati

kepcrluan sebuah enjin petrol dua lejang suntikan terus. Scbuah pcrisian komcrsial

pengkomputeran mekanik bendalir FLUENT telah digunakan scbagai alat untuk

menganalisa prestasi rekabentuk konsep tersebut. Scbuah prototaip telah difabrikasi

bilamana rekabentuk konsep tersebut memcnuhi kesemua kchendak yang telah

digariskan. Prototaip berkenaan kemudiannya melalui beberapa ujian spcsifikasi

sepcrti ujian kebocoran, ujian kadar aliran statik dan ujian pckali semburan. Sebuah

radas ujikaji khusus telah dibina untuk menilai prestasi prototaip tcrsebut. Imcj

semburan yang disinari dengan helaian laser Nd:Y AG pada ketika tertcntu telah

dirakam menggunakan kamera digital berkelajuan tinggi. Imej tersebut telah

dianalisa untuk mendapatkan data sudut semburan dan purata diameter Sauter titisan

pada beza tckanan bahanapi-udara dari 1.0 hingga 5.0 MPa dcngan kenaikan 1.0

MPa. Daripada ujian-ujian tersebut, prototaip tersebut telah mcnepati kehendak yang

telah digariskan iaitu kadar aliran statik sebanyak 475 cc/min, scparuh sudut

semburan bersaiz 32° dan purata diameter Sauter titisan bersaiz 19 flm. Akhir sekali,

data eksperimen berkenaan telah dibandingkan dengan data pengiraan yang telah

dibuat terdahulu. Didapati bahawa data cksperimen untuk kadar aliran statik, pckali

semburan, dan purata diameter Sauter adalah lebih tinggi daripada hasil pengiraan

pada beza tekanan bahanapi-udara diantara 1.0 hingga 3.0 MPa. Sebaliknya, data

pengiraan sudut semburan melebihi jangkaan sebanyak 3% pad a kesemua beza

tekanan bahanapi-udara yang diuji.

CHAPTER

TABLE OF CO\TE\TS

TITLE

DECLARATION

DEDICATION

ACKNO\\,LEDGEl\IENT

ABSTRACT

ABSTRAK

TABLE OF CONTENTS

LIST OF TABLES

LIST OF FIGURES

LIST OF SYMBOLS

LIST OF ABBREVIA TIONS

LIST OF APPENDI CES

INTRODucnON

1.1 Problem Background

1.--1

Research Objecti\"es and Sc()pe

Importance of the Study and P(1tential Contributions

Contents of Thesis

'. :t

ii

iii

\"II

:xii

:x:xii

-1

\'i i i

2 LITERA TURE REVIEW 7

2.1 Overview 7

2.2 Gasoline Direct Injection 7

2.3 Atomization Approach II

2.4 Pressure-swirl or Simplex Atomizer 14

2.4.1 Discharge Coefficient 16

2.4.2 Initial Spray Angle 19

2.4.3 Liquid Sheet Thickness 21

2.4.4 Mean Droplet Size 22

2.5 CFD Assisted Analysis 25

2.5.1 CFD Codes 26

2.5.2 Single-component Test Fluid 27

2.5.3 Internal Flow Calculation 29

2.5.4 Discrete Spray Prediction 32

2.6 Testing and Measuring Standard 33

2.7 Droplet Size Measurement 34

2.7.1 Spatial and Temporal Sampling Techniques 36

2.7.2 Sample Size 37

2.7.3 Sampling Location 37

2.7.4 High-speed Photography 38

2.8 Summary 39

3 METHODOLOGY 41

3.1 Overview 41

3.2 Identifying Application Platform 43

IX

3.3 Determining Specific Requirements ..+4

3.3.1 Injector Duty Cycle ..+5

3.3.2 Injector Static Flow Rate 47

3.3.3 Spray Angle 49

3.3.4 Mean Droplet Size 50

3.3.5 Fuel Operating Pressure 5 I

3.3.6 Spray Pattern 52

3.3.7 Special Features 53

3.4 CFD Calculations 54

3.4.1 Eulerian Multiphase 55

3.4.2 Lagrangian Discrete Phase 59

3.5 Specification Test 63

3.6 Spray Performance Test 66

3.6.1 Basic Operation 68

3.6.2 High Pressure Fuel Pump 70

3.6.3 Laser Illumination 70

3.6.4 Droplet Size Analysis 71

3.6.5 Experiment Procedure 71

4 PROTOTYPE DEVELOPMENT 74

4.1 Overview 74

4.2 Initial Conceptual Design 74

4.2.1 The Nozzle 75

4.2.2 The Swirler 77

4.2.3 The Needle 78

4.2.4 The Body and the Lock 78

4.3 Prototype Fabrication and Assembly 79

4.4 Leak Test 80

4.5 Prototype Evolution 81

4.5.1 Needle Evolution 83

4.5.2 Solenoid Evolution 84

4.5.3 Injector Driver Circuit Upgrade 86

4.5.4 Swirler Evolution 87

4.5.5 Nozzle Evolution 88

4.6 Final Design 89

5 RESULTS AND DISCUSSIONS 91

5.1 Overview 91

5.2 CFD Multiphase 92

5.3 CFD Discrete Phase 97

5.3.1 Free Spray 98

5.3.2 In-cylinder Spray 103

5.4 Static Flow Rate and Discharge Coefficient 105

5.5 Spray Performance 108

5.5.1 Initial Spray Angle 109

5.5.2 Mean Droplet Size 109

5.6 Computational and Experimental Comparison 110

5.7 SMD Prediction Approaches Comparison 115

6 CONCLUSIONS 118

6.1 Summary 118

Xl

6.2 Future Works 119

6.2.1 A Two-stroke ODI Engine Performance Test 119

6.2.2 2D versus 3D Eulerian Multiphase CFD Calculation 120

6.2.3 Effect of Fuel Temperature on Atomization 120

6.2.4 Effect of Fuel Surface Tension on Atomization 121

6.2.5 Liquid Sheet Thickness of a Pressure-swirl Atomizer 121

6.2.6 Droplet SMD Prediction Approaches - A Critical Review 122

6.2.7 In-cylinder Droplet SMD 123

6.2.8 Discrete Phase Prediction from a Multiphase Calculation 124

REFERENCES 125

Appendices A-F 134 - 139

XII

LIST OF TABLES

TABLE NO. TITLE PAGE

2.1 Features comparison between several atomizing techniques used in ODI applications (Liu, 2000) 14

2.2 Empirical correlations for mean droplet size generated by pressure-swirl atomizers (Lefebvre, 1989; Liu, 2000) 24

2.3 Factors affecting droplet size (Schick, 1997) 25

2.4 Some of the CFD codes used in the development of two-stroke ODI engine 26

2.5 Test fluid properties at 293 K (ILemmon cl al., 2005; 2Bauer, 2000) 28

2.6 Droplet size measurement techniques adapted from Chigier (1983), Lefebvre (1989), Williams (1990), or Liu (2000) 35

2.7 Influence of sample size on the accuracy of droplet size measurements (Lefebvre, 1989) 37

3.1 Engine platform specifications (Aziz cl al., 2005) 43

3.2 Flexible control strategy for the prototype injector 54

3.3 Conceptual injector specification for a 125 cc two-stroke gasoline engine 54

3.4 Eulerian multi phase calculation setting 58

3.5 Inlet swirl intensity unit vector components 59

3.6 Free spray discrete phase calculation setting 61

X 111

3.7 Free spray discrete phase calculation injection inputs 61

3.8 In-cylinder discrete phase calculation setting 63

3.9 List of apparatus for static flow rate test 64

3.10 List of apparatus for performance test 67

4.1 Evolution of prototype injector components 82

4.2 Improvements and weaknesses of prototype injector mark 0 to VI 82

4.3 A comparison of needle material and weight 84

4.4 Calculated specification of solenoid B 85

4.5 A maximum ratings comparison between Darlington transistor BDX53C and BDW42 (STMicroelectronics, 1999; ON Semiconductor, 2002) 86

5.1 Result analysis for static flow rate test 107

5.2 Measured spray half-cone angle, e (0) 109

5.3 Droplet SMD measurements result 110

5.4 Droplet SMD prediction approaches 115

6.1 More droplet SMD prediction approaches 122

xiv

LIST OF FIGURES

FIGURE NO. TITLE PAGE

l.1 Problems of two-stroke engine in comparison with similar four-stroke counterparts (Heywood, 1988; Blair, 1996; Stone, 1997) 2

2.1 Most important GDI developments in the past five decades (Iwamoto et al., 1997; Queiroz and Tomanik, 1997; Zhao et al., 1997; Houston and Cathcart, 1998; Brooke, 1999; Sogawa and Kato, 2001) 8

2.2 Enhanced version of Preussner et al. (1998) mixture formation mechanism system analysis adapted for two-stroke engine application 10

2.3 (a) Cross-section of a GDI injector, (b) geometrical region that has great influence on the spray characteristics, (c) volume of fluid of the tangential swirl slots, swirl chamber, and final orifice 16

2.4 (a) Evolution of liquid spray structure with injection pressure (Lefebvre, 1989), and (b) Evolution of discharge coefficient and cone angle for a pressure-swirl atomizer (Cousin et al., 1998) 17

2.5 Effect of several combinations of needle-tip shapes and swirl intensities on discharge coefficient (Aziz and Ali, 2006c) 18

2.6 A sketch of three stages in LISA spray model (Suh and Rutland, 1999) 19

2.7 Metric for spray cone angle determination using (a) imagery of backlit spray, and (b) spray waist diameter along with spray penetration (Zhao et al.,2002) 20

xv

2.8 Liquid sheet breakup nomenclature (Cousin and Nuglisch,2001) 22

2.9 Representation of droplet sampling techniques: (a) Spatial, and (b) Temporal (Schick, 1997) 36

3.1 Research methodology flow diagram 42

3.2 Cross-section of two-stroke compound-piston gasoline engine (Aziz et al., 2005) 44

3.3 Seven important areas that constitute to a pressure-swirl injector specification 45

3.4 Typical port timing of a two-stroke engine 46

3.5 Static allowable injection period for the prototype step-piston two-stroke gasoline engine 46

3.6 Combustion chamber cross-section geometry 49

3.7 Theoretical optimum spray angle, 80PI

50

3.8 Mapping of Lefebvre (1983) droplet SMD correlation for pressure-swirl atomizer 51

3.9 Exhaust emissions by various combination of combustion chamber configuration and injector orientation (Sogawa and Kato, 2001) 53

3.10 (a) Volume of fluid of the tangential swirl slots, swirl chamber, and final orifice, and (b) 2D swirling section of the calculated region 56

3.11 (a) Representation of fuel inlet vector entering needle seat passage from angled tangential slots, viewed from Nozzle Exit, and (b) boundaries of a 2D rotating region 57

3.12 2D domain for Eulerian multiphase calculation, (a) CINJ-0500, (b) CINJ-0600, and (c) MitslIbishi GDI injector 59

3.13 In-cylinder calculation domain 62

3.14 Schematic apparatus setup for static flow rate test 64

3.15 Photograph of the static flow test rig 65

xvi

3.16 Schematic apparatus setup for spray performance test 68

3.17 Part of the dedicated spray performance test rig 69

3.18 Spray performance test procedure flow diagram 72

3.19 Five spatial droplet-sampling regions 73

4.1 Exploded isometric view of prototype injector mark 0 (CINJ-0100) 75

4.2 Mapping of correlation between nozzle orifice diameter and static flow rate with a given discharge coefficient CD. The formula was obtained from Heywood (1988) where A is the

76 cross section area of the nozzle orifice

4.3 Injector assembly (CINJ-0100) + wire harness + o-ring 79

4.4 Injector assembly (CINJ-OI00) 79

4.5 Nozzle (PNZL-O 1 00) 80

4.6 Swirler (PSWL-O 1 00) 80

4.7 (Left) Needle (PNDL-OIOO), sub-assembly of Nozzle + Swirler 80

4.8 (Left) sub-assembly of injector Body (CBDY-0100) + Solenoid (CSNDA0100), and Lock (PLCK-0100) 80

4.9 (Left to right) CNDL-OIOO, CNDL-0200, and CNDL-0300 84

4.10 (Left) PBDY-OIOO and PBDY-0101 85

4.11 (Left) Abdullah (2003) original injector driver circuit, and upgraded driver circuit 87

4.12 (Left) PSWL-0100 and PSWL-0200 88

4.13 (Left) PNZL-OI00 and PNZL-0200 89

4.14 Schematic of injector mark VI (CINJ-0600) 90

4.15 Working prototype injector mark VI (CINJ-0600) 90

xvii

5.1 Contour of fuel volume fraction at several pressure differentials for: (top to bottom) CINJ-0500, CINJ-0600, and MitslIbishi GDI injector 93

5.2 Computed liquid sheet thicknesses, t f at several

pressure differentials 95

5.3 Computed initial spray angles, e at several pressure differentials 96

5.4 Computed theoretical droplet SMD using Wang-Lefebvre correlation at several pressure differentials 97

5.5 CINJ -0500 free spray at 0.5, 1.0 and 1.5 ms after SOl with pressure differential of 1.0, 3.0 and 5.0 MPa 99

5.6 CINJ-0600 free spray at 0.5, 1.0 and 1.5 ms after SOl with pressure differential of 1.0, 3.0 and 5.0 MPa 100

5.7 MitslIbishi GDI free spray at 0.5, 1.0 and 1.5 after SOl with pressure differential of 1.0, 3.0 and 5.0 MPa 101

5.S Spray images of a pressure-swirl injector at several time steps captured with a high-speed camera (Kawahara et at., 2004) 102

5.9 Computed droplet SMD using Lagrangian discrete phase approach 102

5.10 In-cylinder spray during compression stroke at 3333 RPM 103

5.11 In-cylinder spray during compression stroke at 6666 RPM 104

5.12 Graph of dynamic flow, Q" against injector pulse

width, PW 106

5.13 Measured droplet SMD 110

5.14 Computed and measured static mass flow rates 111

5.15 Computed and estimated liquid sheet thicknesses, t f

112

5.17

5. IS

6.1

Computed and mea\urcd drnpict S\ 1 D

A comparison or se\·cral dropict S\lD plctiicti(1n

approaches

LOlliS I:nginl'l"ring optical accc\\ cn~inc (Lotu\ Engincering.20()(1)

\ '.; 11

1 1.~

II·!

11 h

LIST OF SYMBOLS

English Symbols

FN

I

Ie

k

krmx

lQ,dQ -

ls,ds -

11

N

Cross-section area of final orifice [mm2]

Total inlet port area [mm2]

Cross-section area of wire [mm2]

Magnetic field [mTesla]

Discharge coefficient [-]

Spray angle correction factor [-]

Droplet mean diameter [!-lm]

Diameter of wire [mm]

Flow number, JilL /(MLPL)Q5 [-]

Current [A]

Collector current [A]

Turbulence kinetic energy [m2/s2]

Wave number of the dominant perturbation [-]

Length and diameter of final orifice [mm]

Length and diameter of swirl chamber [mm]

Mass flow rate [g/s]

No. of droplets [-]

Engine speed [RPM]

No. of turns (wire) [turns]

Pressure [MPa]

Total power dissipation [Watts]

XIX