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ABSTRAK
Pesawat “wing-in-ground effect” (WIG) boleh dianggap sebagai teknologi baru
dalam pengangkutan marin. Keupayaan meluncur pada kelajuan yang tinggi adalah kelebihan
berbanding WIG dengan reka bentuk pengangkutan marin yang lain. Prestasi pesawat WIG
bergantung kepada konfigurasi pesawat dan sangat dipengaruhi oleh rekabentuk sayap.
Dalam tesis ini, ciri-ciri baru aerodinamik sayap dikaji dengan menggunakan kaedah
berangka dan juga secara ujian terowong angin. Sayap pesawat telah dibahagikan kepada tiga
bahagian utama, di mana satu sayap segi empat tepat di tengah-tengah dan dua sayap tirus
songsang dengan sudut dwisatah negatif di sisi. Aerofoil jenis NACA6409 telah dipilih
sebagai kajian kes ke atas rentas sayap. Pengiraan dinamik bendalir dalam tiga dimensi telah
digunakan sebagai model berangka. Persamaan keterusan dan juga persamaan momentum
bagi aliran tidak boleh mampat telah digunakan dalam simulasi. Model aliran gelora yang
berbeza telah digunakan untuk simulasi aliran di seluruh permukaan sayap. Untuk tujuan
pengesahan, ujikaji menggunakan terowong angin telah dijalankan, dan juga perbandingan
dengan hasil ujikaji dari penyelidik lain yang telah diterbitkan untuk memastikan hasil
simulasi berangka bertepatan dengan mereka. Ujikaji telah dijalankan di terowong angin
berkelajuan rendah, Universiti Teknologi Malaysia, dan daya aerodinamik dan momen telah
diukur dengan menggunakan sel beban paksi berbilang JR3. Pekali utama aerodinamik bagi
kedua-dua jenis sayap seperti pekali daya angkat, pekali seretan, nisbah daya angkat, dan
daya seret dikaji bagi jarak dari dataran dan sudut lancaran yang berbeza. Didapati bahawa,
pada jarak dari dataran yang rendah, pekali aerodinamik pada sayap kompaun dapat
meningkatkan kecekapan sayap pesawat. Kesan parameter reka bentuk seperti saiz rentang
sayap tengah dan sudut dwisatah juga telah dikaji bagi memoptimumkan sayap kompaun.
Bagi sayap kompaun, apabila rentang bahagian tengah sayap dikurangkan, nisbah daya
angkat terhadap daya seret meningkat dengan jelas. Sayap kompaun juga dapat menjimatkan
penggunaan bahan api dan secara langsung mengurangkan pencemaran dengan pelepasan gas
CO2 yang lebih rendah. Reka bentuk sayap kompaun ini boleh digunakan untuk
meningkatkan kelebihan kesan dataran bagi pesawat WIG generasi baru.
brought to you by COREView metadata, citation and similar papers at core.ac.uk
provided by Universiti Teknologi Malaysia Institutional Repository
vii
TABLE OF CONTENTS CHAPTER TITLE
PAGE
DECLARATION ii
DEDICATION iii
ACKNOWLEDGEMENT iv
ABSTRACT v
ABSTRAK vi
TABLE OF CONTENTS vii
LIST OF TABLES xiii
LIST OF FIGURES xviii
LIST OF ABBREVIATIONS xxvii
LIST OF SYMBOLS xxix
LIST OF APPENDICES
xxxii
1 INTRODUCTION
1.1 Background
1.2 Statement of problem
1.3 Research objectives
1.4 Scope of study
1.5 Significance of the study
1.6 Organisation of thesis
1
1
3
4
4
6
6
2 LITERATURE SURVEY
2.1 Introduction
2.1.1 Span dominated ground effect
2.1.2 Chord dominated ground effect
2.2 Literature review
9
9
10
10
11
viii
2.2.1 Aerodynamic characteristic of wing near
ground
2.2.2 Influence of wing configuration on
aerodynamic performance in ground effect
2.2.3 Flow separation and wake region behind wing
near ground
2.2.4 Aerodynamic characteristics of WIG craft on
free surface
2.2.5 Optimal design of wing in ground effect
2.2.6 Aerodynamic characteristic of a multi-element
wing near ground
2.2.7 Effect of power ram engine on aerodynamic
performance of WIG craft
2.2.8 Aerodynamics of wing via viscous ground
effect in ground proximity
2.2.9 Fuel consumption and environmental impact of
craft
11
18
20
28
30
32
33
37
39
3 METHODOLOGY
3.1 Introduction
3.2 Computational methodology
3.2.1 General
3.2.2 CFD simulation
3.2.2.1 Pre-processing
3.2.2.2 Solver
3.2.2.3 Post-processing
3.2.3 Mathematical model
3.2.4 Turbulent models
3.2.4.1 Standard k-ε turbulent model
3.2.4.2 k-ω SST turbulent model
3.2.4.3 Realizable k-ε turbulent model
3.2.5 Boundary layer at near-wall
3.2.6 Standard wall functions
42
42
43
43
43
43
44
44
45
45
45
49
50
51
53
ix
3.2.7 Pressure-Based Solver
3.2.8 Shape of linear formulation
3.2.9 Boundary conditions
3.2.9.1 Wall boundary condition
3.2.9.2 Velocity -inlet boundary condition
3.2.9.3 Pressure outlet boundary condition
3.2.9.4 Symmetry boundary conditions
3.2.10 Solutions controls 3.2.10.1 Discretisation
3.2.10.2 Under-relaxation factors
3.2.10.3 Pressure-Velocity Coupling Method
3.2.11 Meshing
3.2.12 Post-processing
3.3 Experimental methodology
3.3.1 Wind tunnel
3.3.1.1 Theory of operation
3.3.1.2 How does wind tunnel work?
3.3.2 UTM Wind tunnel
3.3.2.1 Introduction to UTM Wind Tunnel
facility
3.3.2.2 Test section
3.3.2.3 Fan motor and drive system
3.3.2.4 Settling chamber
3.3.2.5 Balance System
3.3.2.6 Facility control system
3.3.3 Wing Model
3.3.4 Experimental procedures and set-up
54
56
57
57
58
58
59
59
59
60
60
61
62
63
63
63
63
64
64
65
66
67
67
68
68
70
4
NUMERICAL AERODYNAMIC
CHARACTERISTICS OF A NEW COMPOUND
WING INTRODUCTION
4.1 General
4.2 CFD Numerical study
73
73
73
x
4.3 Validation of CFD simulation
4.3.1 Lift Coefficient (CL)
4.3.2 Drag Coefficient (CD)
4.3.3 Lift to drag ratio (L/D)
4.4 Result and discussion
4.4.1 Lift Coefficient (CL)
4.4.2 Drag Coefficient (CD)
4.4.3 Lift to drag ratio (L/D)
78
78
80
82
84
84
86
88
5 EXPERIMENTAL AERODYNAMIC
CHARACTERISTICS OF A NEW COMPOUND
WING
5.1 General
5.2 Repeatability of experiment
5.3 Principal aerodynamic forces of compound and
rectangular wing
5.3.1 Lift coefficient
5.3.2 Drag coefficient
5.3.3 Moment coefficient
5.4 Comparison of aerodynamic coefficients between
compound and rectangular wings
5.4.1 Lift coefficient
5.4.2 Drag coefficient
5.4.3 Lift to drag ratio
5.4.4 Drag polar
5.4.5 Moment coefficient
5.4.6 Centre of pressure
5.5 Tendency of numerical and experimental simulations
91
91
92
92
93
94
95
96
96
98
100
102
104
106
108
6 DESIGN PARAMETRIC STUDY OF
CONFIGURATION OF COMPOUND WING
6.1 General
6.2 CFD Numerical study
6.3 Validation of CFD simulation
110
110
110
114
xi
6.3.1 Lift Coefficient (CL)
6.3.2 Drag Coefficient (CD)
6.3.3 Lift to drag ratio (L/D)
6.4 Design parametric study of compound wing
6.4.1 Span size
6.4.1.1 Pressure and velocity contours
6.4.1.2 Lift coefficient
6.4.1.3 Drag coefficient
6.4.1.4 Lift to drag ratio
6.4.1.5 Moment coefficient and centre of
pressure
6.4.2 Anhedral angle (a)
6.4.2.1 Pressure and velocity contours
6.4.2.2 Lift coefficient
6.4.2.3 Drag coefficient
6.4.2.4 Lift to drag ratio
6.4.2.5 Moment coefficient and centre of
pressure
6.4.3 Taper ratio (λ)
6.4.3.1 Pressure and velocity contours
6.4.3.2 Lift coefficient
6.4.3.3 Drag coefficient
6.4.3.4 Lift to drag ratio
6.4.3.5 Moment coefficient and centre of
pressure
6.4.4 Ground clearance
6.4.4.1 Pressure and velocity contours
6.4.4.2 Lift coefficient
6.4.4.3 Drag coefficient
6.4.4.4 Lift to drag ratio
6.4.4.5 Moment coefficient and centre of
pressure
6.4.5 Reynolds number
115
116
117
118
118
118
122
124
125
126
129
129
133
136
137
135
139
139
142
143
145
146
148
148
151
153
154
155
158
xii
6.4.5.1 Pressure and velocity contours
6.4.5.2 Lift coefficient
6.4.5.3 Drag coefficient
6.4.5.4 Lift to drag ratio
6.4.5.5 Moment coefficient and centre of
pressure
6.4.6 Stall angle
6.4.6.1 Pressure and velocity contours
6.4.6.2 Dropping lifts and stall angle
6.4.7 Comparison of the affect of design parameters
6.4.7.1 Lift coefficient
6.4.7.2 Drag coefficient
6.4.7.3 Lift to drag ratio
6.4.7.4 Moment coefficient and centre of
pressure
6.5 Fuel consumption and CO2 emission
158
160
162
163
165
167
167
168
169
169
170
172
173
175
7 CONCLUSION AND FUTURE WORK
7.1 Conclusion
7.2 Recommendation for Further Work
178
178
181
REFERENCES 182
Appendices A-C 194-213
xiii
LIST OF TABLES
TABLE NO. TITLE PAGE
3.1 Mesh elements 61
3.2 Type of meshing scheme. 61
3.3 The load capacities of JR3 sensor 67
3.4 Principle dimension of wings 69
4.1 Principle dimension of wings. 76
4.2 Lift coefficient versus angle of attack for h/c = 0.1 and
AR = 1 based on experimental and numerical result 79
4.3 Lift coefficient versus ground clearance for angle of attack
2º and AR = 1 based on experimental and numerical result 79
4.4 Drag coefficient versus angle of attack for h/c = 0.1and
AR = 1 based on experimental and numerical result 81
4.5 Drag coefficient versus ground clearance for angle of attack
2º and AR = 1 based on experimental and numerical result 81
4.6 Lift to drag ratio versus angle of attack for h/c = 0.1and
AR = 1 based on experimental and numerical result 83
4.7 Lift to drag ratio versus ground clearance for angle of attack
2º and AR = 1 based on experimental and numerical result 83
4.8 Lift coefficient versus angle of attack with h/c = 0.1and
AR = 1.25 for rectangular and compound wing 85
4.9 Lift coefficient versus ground clearance with angle of attack
2º and AR = 1.25 for rectangular and compound wing 85
4.10 Drag coefficient versus angle of attack with h/c = 0.1and
AR = 1.25 for rectangular and compound wing 87
4.11 Drag coefficient versus ground clearance with angle of
attack 2º and AR = 1.25 for rectangular and compound wing 87
xiv
4.12 Lift to drag ratio versus angle of attack with h/c = 0.1 and
AR = 1.25 for rectangular and compound wing 89
4.13 Lift to drag ratio versus ground clearance with angle of
attack 2º and AR = 1.25 for rectangular and compound wing 89
5.1 Reynolds number 96
6.1 Principle dimension of rectangular wing and compound
wings with different middle wing span 112
6.2 Principle dimension of compound wings with different
anhedral angle 112
6.3 Principle dimension of compound wings with different taper
ratio 113
6.4 Lift coefficient versus Angle of attack with ground
clearance (h/c) of 0.15 and AR = 1.25 for experimental and
present numerical result 115
6.5 Drag coefficient versus Angle of attack with ground
clearance (h/c) of 0.15 and AR = 1.25 for experimental and
present numerical result 116
6.6 Lift to drag ratio versus Angle of attack with ground
clearance (h/c) of 0.15 and AR = 1.25 for experimental and
present numerical result 117
6.7 Lift coefficient and increment (In) versus angle of attack
(A) at ground clearance (h/c) of 0.15 for rectangular (R) and
compound wings (C) 123
6.8 Drag coefficient and reduction (Re) versus angle of attack
(A) at ground clearance (h/c) of 0.15 for rectangular (R) and
compound wings 124
6.9 Lift to drag ratio and increment (In) versus angle of attack
(A) at ground clearance (h/c) of 0.15 for rectangular (R) and
compound wings (C) 126
6.10 Moment coefficient and reduction (Re) versus angle of
attack (A) at ground clearance (h/c) of 0.15 for rectangular
(R) and compound wings (C)
127
xv
6.11 Centre of pressure coefficient and reduction (Re) versus
angle of attack (A) at ground clearance (h/c) of 0.15 for
rectangular (R) and compound wings (C) 128
6.12 Lift coefficient and its increment versus anhedral angle at
ground clearance (h/c) of 0.15 and angle of attack of 4° 134
6.13 Drag coefficient and its reduction versus anhedral angle at
ground clearance (h/c) of 0.15 and angle of attack of 4° 135
6.14 Lift to drag ratio and its increment versus anhedral angle at
ground clearance (h/c) of 0.15 and angle of attack of 4° 136
6.15 Moment coefficient and its increment versus anhedral angle
at ground clearance (h/c) of 0.15 and angle of attack of 4° 138
6.16 Centre of pressure and its reduction versus anhedral angle at
ground clearance (h/c) of 0.15 and angle of attack of 4° 139
6.17 Lift coefficient and its reduction versus taper ratio (TR) at
ground clearance (h/c) of 0.15 and angle of attack of 4° 143
6.18 Drag coefficient and its reduction versus taper ratio at
ground clearance (h/c) of 0.15 and angle of attack of 4° 144
6.19 Lift to drag ratio and its increment versus taper ratio at
ground clearance (h/c) of 0.15 and angle of attack of 4° 145
6.20 Moment coefficient and its reduction versus taper ratio at
ground clearance (h/c) of 0.15 and angle of attack of 4° 147
6.21 Centre of pressure and its reduction versus taper ratio at
ground clearance (h/c) of 0.15 and angle of attack of 4° 148
6.22 Lift coefficient and its increment versus ground clearance at
angle of attack of 4º for rectangular wing and compound
wing-1 152
6.23 Drag coefficient and its reduction versus ground clearance
at angle of attack of 4º for rectangular wing and compound
wing-1 153
6.24. Lift to drag ratio and its increment versus ground clearance
at angle of attack of 4º for rectangular wing and compound
wing-1
155
xvi
6.25. Moment coefficient and its reduction versus ground
clearance at angle of attack of 4º for rectangular wing and
compound wing-1 156
6.26 Centre of pressure and its reduction versus ground clearance
at angle of attack of 4º for rectangular wing and compound
wing-1 157
6.27 Lift coefficient and its increment versus Reynolds number
at ground clearance of 0.15 and angle of attack of 4º for
rectangular wing and compound wing-4 161
6.28 Drag coefficient and its reduction versus Reynolds number
at ground clearance of 0.15 and angle of attack of 2º for
rectangular wing and compound wing-4 163
6.29 Lift to drag ratio and its increment versus Reynolds number
at ground clearance of 0.15 and angle of attack of 2º for
rectangular wing and compound wing-4 164
6.30 Moment coefficient and its reduction versus Reynolds
number at ground clearance of 0.15 and angle of attack of 2º
for rectangular wing and compound wing-4 165
6.31 Centre of pressure and its reduction versus Reynolds
number at ground clearance of 0.15 and angle of attack of 2º
for rectangular wing and compound wing-4 166
6.32 Lift coefficient and its increment versus angle of attack at
ground clearance of 0.15 for compound wing-1 and
compound wing-7 170
6.33 Drag coefficient and its increment versus angle of attack at
ground clearance of 0.15 for compound wing-1 and
compound wing-7 171
6.34 Lift to drag ratio and its increment versus angle of attack at
ground clearance of 0.15 for compound wing-1 and
compound wing-7 172
6.35. Moment coefficient and its reduction versus angle of attack
at ground clearance of 0.15 for compound wing-1 and
compound wing-7 174
xvii
6.36 Centre of pressure and its reduction versus angle of attack at
ground clearance of 0.15 for compound wing-1 and
compound wing-7 175
6.37 Rate of fuel consumption and CO2 emission of wings versus
angle of attack for h/c = 0.1 and AR = 1.25 176
6.38 Rate of fuel consumption and CO2 emission of rectangular
wing and compound wing-1 versus ground clearance for
angle of attack of 4° and AR = 1.25 177
xviii
LIST OF FIGURES FIGURE NO. TITLE PAGE
2.1 Aerodynamic coefficient of front wing versus angle of
attack (Kieffer et al., 2006)
27
2.2 WIG craft on wavy surface with course angle β(Yang et
al., 2010b) 28
2.3 Periodic aerodynamic coefficients (Yang et al., 2010b) 29
2.4 Cyclic roll moment (Yang et al., 2010b) 30
2.5 Multi-element wing (Xuguo et al., 2009) 32
2.6 Aerodynamic coefficients versus ground clearance (Xuguo
et al., 2009) 33
2.7 Aerodynamic forces versus ground clearance (h/c) for
different relative jet velocity (vjet/v∞), and angle of attack
θ° =0 (Yang and Yang, 2010) 35
2.8 Aerodynamic forces versus angle of attack (θ°) for
different relative jet velocity (vjet/v∞), and h/c=0. 3 (Yang
and Yang, 2010)
35
2.9 Aerodynamic forces versus nozzle angle (θ°) for different
ground clearance (h/c) (Yang and Yang, 2011)
36
2.10 Power-augmented ram vehicle (Matveev, 2008) 36
2.11 Amphibious craft (Sitek and Yang, 2011) 37
2.12
The pollutant emissions for several years (Kurniawan and
Khardi, 2011) 41
3.1 Compound wing 42
3.2 Near-wall modelling 53
3.3 Pressure-based solver, (a) segregated algorithm,
(b) coupled algorithm 56
xix
3.4 Mesh element and type of meshing near region from wing 62
3.5 Meshing of whole region around the wing 62
3.6 Universiti Teknologi Malaysia low speed wind tunnel
(Mansor, 2009) 65
3.7 The test section and a 6-components balance/load-cell to
measure aerodynamic forces and moment in 3 dimensional
loads (Mansor, 2009) 66
3.8 Power consumption of motor versus wind speed (Mansor,
2009) 66
3.9 JR3 sensor NO. 50M31A3-125 (JR3, Inc) 67
3.10 Facility of control room (Mansor, 2009) 68
3.11 Types of wing configuration, (a) Rectangular wing, (b)
Compound wing 69
3.12 Sketch of (a) Rectangular wing, (b) Compound wing 69
3.13 Experimental setup in low speed wind tunnel of Universiti
Teknologi Malaysia 70
3.14 Wing mounting by one strut 71
3.15 Supporting system 72
3.16 Monitoring force measurements 72
4.1 Types of wing configuration, (a) Rectangular wing, (b)
Compound wing, (c) Explanation of compound wing 75
4.2 Grid independency of numerical simulation, (a) Lift
coefficient, (b) Drag coefficient
77
4. 3 Meshing of rectangular wing 77
4. 4 Meshing of compound wing 78
4.5 Lift coefficient versus angle of attack for h/c = 0.1 and
AR = 1
79
4.6 Lift coefficient versus ground clearance for angle of
attack 2º and AR = 1
80
4.7 Drag coefficient versus angle of attack for h/c = 0.1 and
AR = 1 81
4.8 Drag coefficient versus ground clearance for angle of
attack 2º and AR= 1
82
xx
4.9 Lift to drag ratio versus angle of attack for h/c = 0.1 and
AR = 1 83
4.10 Lift to drag ratio versus ground clearance for angle of
attack 2º and AR=1 84
4.11 Lift coefficient versus angle of attack for h/c = 0.1 and
AR = 1.25 86
4.12 Lift coefficient versus ground clearance for angle of attack
2º and AR = 1.25 86
4.13 Drag coefficient versus angle of attack for h/c = 0.1 and
AR = 1.25 88
4.14 Drag coefficient versus ground clearance for angle of
attack 2º and AR = 1.25
88
4.15 Lift to drag ratio versus angle of attack for h/c = 0.1 and
AR = 1.25 90
4.16 Lift to drag ratio versus ground clearance for angle of
attack 2º and AR = 1.25 90
5.1 Mounting of compound wing inside UTM-LST 91
5.2 Repeatability of experimental test (a) Lift coefficient and
(b) drag coefficient 92
5.3 Lift coefficient versus ground clearance (h/c) at different
angle of attack (AOA) and air speed for a) rectangular
wing and b) compound wing 93
5.4 Drag coefficient versus ground clearance (h/c) at
different angle (AOA) of attack and air speed for a)
rectangular wing and b) compound wing 94
5.5 Moment coefficient versus ground clearance (h/c) at
different angle of attack (AOA) and air speed for a)
rectangular wing and b) compound wing 95
5.6 Lift coefficient of rectangular and compound wing versus
angle of attack (α°) for different ground clearance (h/c)
and Reynolds number (Re) 98
xxi
5.7 Drag coefficient of rectangular and compound wing versus
angle of attack (α°) for different ground clearance (h/c)
and Reynolds number (Re)
100
5.8 Lift to drag ratio of rectangular and compound wing versus
angle of attack (α°) for different ground clearance (h/c)
and Reynolds number (Re) 102
5.9 Drag polar of rectangular and compound wing for different
ground clearance (h/c) and Reynolds number (Re) 104
5.10 Moment coefficient of rectangular and compound wing
versus angle of attack (α°) for different ground clearance
(h/c) and Reynolds number (Re) 106
5.11 Center of pressure of rectangular and compound wing
versus angle of attack (α°) for different ground clearance
(h/c) and Reynolds number (Re) 108
5.12 Comparison of experimental and numerical simulation
results at ground clearance of 0.15, (a) Lift coefficient,
(b) Drag coefficient, (c) Lift to drag ratio 109
6.1 Types of wing configuration, (a) Rectangular wing, (b)
Compound wing, (c) Explanation of the compound wing 111
6.2 Grid independency of numerical simulation, (a) Lift
coefficient, (b) Drag coefficient 113
6.3 Meshing of rectangular wing 114
6.4 Meshing of compound wing 114
6.5 Lift coefficient (CL) versus angle of attack for ground
clearance (h/c) of 0.15 and AR = 1.25 116
6.6. Drag coefficient (CD) versus angle of attack for ground
clearance (h/c) of 0.15 and AR = 1.25 117
6.7 Lift to drag ratio (L/D) versus angle of attack for ground
clearance (h/c) of 0.15 and AR = 1.25 118
6.8 Pressure coefficient contour on upper and lower surface of
wings at ground clearance of 0.15 and angle of attack of 8° 119
6.9 Pressure coefficient contour on the middle span of wings
at ground clearance of 0.15 and angle of attack of 8° 120
xxii
6.10 Velocity vector colored by pressure coefficient on the
middle span of wings at ground clearance of 0.15 and
angle of attack of 8° 120
6.11 Velocity contour (m/s) on middle span of wings at
ground clearance of 0.15 and angle of attack of 8° 121
6.12 Velocity vector colored by velocity magnitude (m/s) on
the middle span of wings at ground clearance of 0.15 and
angle of attack of 8° 121
6.13 Pressure coefficient distribution near wingtip of wings at
ground clearance of 0.15 and angle of attack of 8° 122
6.14 Lift coefficient (CL) versus angle of attack at ground
clearance (h/c) of 0.15 123
6.15 Drag coefficient (CD) versus angle of attack at ground
clearance (h/c) of 0.15 125
6.16 Lift to drag ratio (L/D) versus angle of attack at ground
clearance (h/c) of 0.15 126
6.17 Moment coefficient (CM) versus angle of attack at ground
clearance (h/c) of 0.15 128
6.18 Centre of pressure (XCP/c) versus angle of attack at ground
clearance (h/c) of 0.15 129
6.19 Pressure coefficient contour on upper and lower surface of
compound wings at ground clearance of 0.15 and angle of
attack of 4° 130
6.20 Pressure coefficient contour on the middle span of
compound wings at ground clearance of 0.15 and angle
of attack of 4° 131
6.21 Velocity vector colored by pressure coefficient on the
middle span of compound wings at ground clearance of
0.15 and angle of attack of 4° 131
6.22 Velocity contour (m/s) on the middle span of compound
wings at ground clearance of 4.15 and angle of attack of 4°
132
xxiii
6.23 Velocity vector colored by velocity magnitude (m/s) on the
middle span of compound wings at ground clearance of
0.15 and angle of attack of 4°
132
6.24 Pressure coefficient distribution near wingtip of compound
wings at ground clearance of 0.15 and angle of attack of 4° 133
6.25 Lift coefficient (CL) versus anhedral angle at ground
clearance of 0.15 and angle of attack of 4° 134
6.26 Drag coefficient (CD) versus anhedral angle at ground
clearance of 0.15 and angle of attack of 4° 135
6.27 Lift to drag ratio (L/D) versus anhedral angle at ground
clearance of 0.15 and angle of attack of 4° 137
6.28 Moment coefficient (CM) versus anhedral angle at
ground clearance of 0.15 and angle of attack of 4° 138
6.29 Centre of pressure (XCP/c) versus anhedral angle at ground
clearance of 0.15 and angle of attack of 4°
139
6.30 Pressure coefficient contour on upper and lower surface of
compound wings at ground clearance of 0.15 and angle of
attack of 4° 140
6.31 Pressure coefficient contour on the middle span of
compound wings at ground clearance of 0.15 and angle of
attack of 4° 141
6.32 Velocity contour (m/s) on the middle span of compound
wings at ground clearance of 0.15 and angle of attack of 4° 141
6.33 Pressure coefficient distribution near wingtip of compound
wings at ground clearance of 0.15 and angle of attack of 4° 142
6.34 Lift coefficient (CL) versus taper ratio at ground clearance
of 0.15 and angle of attack of 4° 143
6.35 Drag coefficient (CD) versus taper ratio at ground
clearance of 0.15 and angle of attack of 4° 144
6.36 Lift to drag ratio (L/D) versus taper ratio at ground
clearance of 0.15 and angle of attack of 4° 146
6.37 Moment coefficient (CM) versus taper ratio at ground
clearance of 0.15 and angle of attack of 4°
147
xxiv
6.38 Centre of pressure (XCP/c) versus taper ratio at ground
clearance of 0.15 and angle of attack of 4° 148
6.39 Pressure coefficient contour on upper and lower surface
of compound wing-1 at ground clearances of 0.1 and 0.4
with angle of attack of 4° 149
6.40 Pressure coefficient contour on the middle span of
compound wing-1 at ground clearances of 0.1 and 0.4 with
angle of attack of 4° 150
6.41 Velocity vector colored by pressure coefficient on the
middle span of compound wing-1 at ground clearances of
0.1 and 0.4 with angle of attack of 4° 150
6.42 Velocity contour (m/s) on the middle span of compound
wing-1 at ground clearances of 0.1 and 0.4 with angle of
attack of 4° 150
6.43 Velocity vector colored by velocity magnitude (m/s) on
the middle span of compound wing-1 at ground clearances
of 0.1 and 0.4 with angle of attack of 4° 151
6.44 Pressure coefficient distribution near wingtip of compound
wing-1 at ground clearances of 0.1and 0.4 with angle of
attack of 4° 151
6.45 Lift coefficient (CL) versus ground clearance at angle of
attack of 4°
152
6.46 Drag coefficient (CD) versus ground clearance at angle
of attack of 4° 154
6.47 Lift to drag ratio (L/D) versus ground clearance at angle of
attack of 4° 155
6.48 Moment coefficient (CM) versus ground clearance at
angle of attack of 4° 157
6.49 Centre of pressure (XCP/c) versus ground clearance at
angle of attack of 4° 158
xxv
6.50 Pressure coefficient contour on upper and lower surface
of compound wing-4 for different Reynolds number at
ground clearance of 0.15 and angle of attack of 4°
159
6.51 Pressure coefficient contour on the middle span of
compound wing-4 for different Reynolds number at
ground clearance of 0.15 and angle of attack of 4° 160
6.52 Pressure coefficient distribution near wingtip of compound
wing-4 for different Reynolds number at ground
clearances of 0.15 and angle of attack of 4° 160
6.53 Lift coefficient (CL) versus Reynolds number at ground
clearance of 0.15 and angle of attack of 4° 162
6.54 Drag coefficient (CD) versus Reynolds number at ground
clearance of 0.15 and angle of attack of 4° 163
6.55 Lift to drag ratio (L/D) versus Reynolds number at
ground clearance of 0.15 and angle of attack of 4° 164
6.56 Moment coefficient (CM) versus Reynolds number at
ground clearance of 0.15 and angle of attack of 4° 166
6.57 Centre of pressure (XCP/c) versus Reynolds number at
ground clearance of 0.15 and angle of attack of 4° 167
6.58 Pressure coefficient contour on upper and lower surface of
compound wing-7 at stall angle and ground clearance of
0.15 168
6.59 Pressure coefficient and velocity contour (m/s) on the
middle span of compound wing-7 at stall angle and
ground clearance of 0.15 168
6.60 Stall angle of rectangular wing and compound wing-7 at
ground clearance of 0.15 169
6.61 Lift coefficient (CL) versus angle of attack at ground
clearance of 0.15
170
6.62 Drag coefficient (CD) versus angle of attack at ground
clearance of 0.15 171
6.63 Lift to drag ratio (L/D) versus angle of attack at ground
clearance of 0.15 173
xxvi
6.64 Moment coefficient (CM) versus angle of attack at ground
clearance of 0.15
174
6.65 Centre of pressure (XCP/c) versus angle of attack at ground
clearance of 0.15 175
xxvii
LIST OF ABBREVIATIONS
AEV - Aero-levitation Electric Vehicle
SL - Sliding mesh
AOA - Angle of attack
AR - Aspect ratio
CFD - Computational fluids dynamic
CoVGs - Co-rotating vortex generators
CtLVG - Counter-rotating large vortex generators
CtSVGs - Counter-rotating subboundary layer vortex generators
DARS Data Acquisition and Reduction System
DM - Dynamic mesh
FS - Forward swept
FVM - Finite volume Method
HAPs - Hazardous air pollutants
HS - Height stability
LDA - Laser Doppler Anemometry
LTO - Landing and take off
LVGs - Large-scale vortex generators
PAR - Power augmented ram
PARV - Power-augmented ram vehicle
PDS - Propeller-deflected slipstream
PIV - Particle image velocimetry
RANS - Reynolds averaged Navier-Stokes
RFS - Reverse forward swept
SQP - Sequential quadratic programming method
SVGs - Subboundary layer vortex generators
TAF - Tandem-Airfoil-Flairboat
xxviii
UTM-LST - Low speed wind tunnel of Universiti Teknologi Malaysia
VGs - Vortex generators
VLM - Vortex lattice method
WIG - Wing-in- ground effect
xxix
LIST OF SYMBOLS
a Anhedral angle
b Wing Span
bm Middle wing span
c Chord length
ct Tip chord length
CL Lift Coefficient
CD Drag Coefficient
CM Moment coefficient
CP Specific fuel combustion
D Drag Force
d Diameter of cylinder
Gb Generation of turbulence kinetic energy due to
buoyancy
Gk Generation of turbulence kinetic energy due to the mean
velocity gradients
Gω Production of ω
h Height of trailing edge of the wing above the ground
h/c Ground clearance
I Turbulence Intensity
K Mean kinetic energy
k Turbulent kinetic energy
kP Turbulence kinetic energy k at the near-wall node P
k(t) Total kinetic energy
L Lift force
L Characteristics length
l Turbulence Length Scale
xxx
L/D Lift to drag ratio
M Pitching moment at c/4 from the leading edge
2COm& Rate of CO2 emission
fm& Rate of fuel consumption
P Mean normal pressure
p Normal pressure
S Wing planform area
SE Specific energy
SCE Specific CO2 emission
Sij Mean rate of deformation tensor
s'ij Fluctuating rate of deformation tensor
Sk User-defined source term for k
Sω User-defined source term for ω
TSFC Trust specific fuel consumption
U Free stream mean velocity
U Mean velocity in x direction
U* Mean velocity of flow near-wall region
Umax Maximum velocity at a distance x downstream of the
source
UP Mean velocity of flow at the near-wall node P
u Velocity in x direction
uj Velocity in jth direction
uτ Friction velocity
u' Fluctuating velocity in x direction
u+ Nondimensional velocity of flow
V Mean velocity in y direction
v Velocity in y direction
vjet Jet velocity
v∞ velocity at infinity
v' Fluctuating velocity in y direction
W Mean velocity in Z direction
iW Initial weight
fW Fuel weight
xxxi
w Velocity in z direction
w' Fluctuating velocity in z direction
CPX Centre of pressure from the leading edge
Xh Height aerodynamic center
Xα Pitch aerodynamic center
x Coordinate in ith direction
YM Effects of compressibility on turbulence
Yk Dissipation of k due to turbulence
Yω Dissipation of ω due to turbulence
y Height of first mesh on wing
y Coordinate in jth direction
yp Distance from point P to the wall
y+ Nondimensional wall distance
z Coordinate in kth direction
α Angle of attack
α Under-relaxation factor
β Course angle
θ Nozzle angle
λ Taper ratio (c/ct)
μ Air viscosity
μt Turbulent viscosity
ηp Propeller efficiency
ε Turbulent energy dissipation rate
ω Turbulence frequency
ρ Air density
Γk Effective diffusivity of k
Γω Effective diffusivity of ω
τw Wall shear stress
φ Quantities value of upstream cell-centre
calcφ Calculated value of quantity φ face
fφ Quantity value of cell face
newφ New value of quantity φ
oldφ Old value of quantity φ
xxxii
LIST OF APPENDICES
APPENDIX TITLE
PAGE
A Aerodynamic characteristics of wing of wig catamaran
vehicle in ground effect 192
B Numerical investigation on fuel consumption of wig
catamaran craft in ground effect 203
C Publications 209
CHAPTER 1
INTRODUCTION
1.1 Background
The wing-in- ground effect (WIG) crafts are classified as a middle form of
aircraft between ships and aircrafts. WIG crafts can fly in proximity to the any
surface such as ground, sea, snow and ice. A high air pressure (air cushion) is
generated from interface between wing of the WIG craft and the ground. The
dropping of down-wash angle because of the ground effect guides to an enhancement
in lift and decline of induce drag, with a raise of effective aspect ratio for the wing.
The enhancement of the lift force and decreasing of the induced drag provides an
augmentation on the lift to drag ratio (L/D) (Yun et al., 2010). The type of air
cushion is the principal difference between hovercraft and WIG craft. A static air
cushion holds hovercraft, while the WIG craft is hold by dynamic air cushion. The
small aspect ratio of wing and high lift to drag ratio of WIG craft are other
differences from a conventional craft. Currently, the suitable expansion of high
power computing and computational fluids dynamic (CFD) grows the numerical
aerodynamic characteristics of WIG crafts (Rozhdestvensky, 2006).
WIG craft will be talented craft for transportation as a new mean for
travelling. The high speed and safety are qualities that could be considered for WIG
craft. Passengers will prefer to faster means for short journey on river, lake, sea
among islands and etc. The passenger boats have a restriction on speed because of
their efficiency; fast boats with speed greater than 100 km/h can not reach to
2
reasonable efficiency. The high speed boats, such as surface effect ships suffer
hydrodynamic resistance, while WIG crafts contact with air where the drag is very
low (Abramowski, 2007). The aerodynamic interface between wings of WIG craft
and ground surface (such as water) named ground effect makes dynamic air cushion
which this phenomenon does not appear for airplane.
There are a lot of concepts of wing-in-ground effect. Initially, the idea of ram
wing was employed into operation by Troeng (Rozhdestvensky, 2006). Practically all
WIG crafts employ high pressure ram effect to improve lift, nevertheless the problem
of ram wing in WIG craft is its stability. According to this concept, a number of WIG
crafts include a low aspect ratio wing (approximately square) and a large horizontal
tail is mounted out of ground effect which supplies the essential stability. Tandem-
Airfoil-Flairboat (TAF) is defined by the proposal of assembling two short wings in
tandem. Both wings have almost an equal size with short distance between them.
This craft is without a horizontal tail. This arrangement presents a good stability in
extreme ground effect, but it is unstable out of ground effect. A special class of ram
wing called as Lippisch, introduces the idea where the main wing includes an inverse
dihedral wing along the leading edge. This design holds more longitudinal stability
with relatively a low aspect ratio ram wing. A smaller horizontal tail is required for
longitudinal stability requirement in low ground clearance and jump modes during
cruise condition. The Lippisch concept uses a greater aspect ratio of wing as
compared with ram wing concept which is near to 3. The lift to drag ratio of Lippisch
crafts is around 25.
The hoverwing craft use a simple system of flexible skirts to hold an air
cushion between the twin hulls. This static air cushion is employed just through take
off for assisting the craft to accelerate with minimal power before shifting to the true
ground effect mode (Rozhdestvensky, 2006). The Hydrofret concept is classified to
use both static air cushion and dynamic ground effect. The concept is planned in two
models. The first is a ram-wing catamaran that is balanced by a large aspect ratio
wing tail. In another different design, a large aspect ratio rear wing is employed
instead of the tail wing (Rozhdestvensky, 2006).
3
The growth of air transportation makes a increasing in environmental impacts
in the world. One technique to reduce this issue, fuel consumption can be controlled.
The pollutant emissions could be affected with the type of fuel, aircraft, engine,
engine load and altitude (Kurniawan and Khardi, 2011).
The atmospheric emissions by aircraft are divided in two parts. First, local
environmental impact belongs to take off and landing of aircraft and second is related
to global effect where aircraft is in climbing and cruise mode which causes alteration
in climate, stratospheric Ozone and etc(Kurniawan and Khardi, 2011).
1.2 Statement of problem
Recently, the wing configuration is a main challenge in designing WIG craft
for increasing the performance, economic point, and reducing the energy
consumption and pollutants emission. Many researchers have investigated the
configuration of wing in proximity to the ground. According to the type of airfoil
section and configuration of wing, they reported different aerodynamic behaviour of
the wings. All researchers have tried to improve two phenomena. First, chord
dominated ground effect that is referred to as ram effect or ram pressure. Second,
span dominated ground effect that it can reduce the tip vortex of wing and
consequently makes a reduction in the induced drag. There are some methods to
improve the advantages of ground effect such as, multi–wing elements, and
employing endplates and flaps. The investigation on wing configuration is still being
performed to increase the benefit of ground effect. However, the high drag (hump
drag) of WIG craft during the take off is the main issue because of high power
requirement that this problem totally has not yet been solved by researchers. The
combination of some concepts of wing-in ground effect can improve the
aerodynamic coefficients such as lift coefficient and lift to drag ratio. In the present
study, a new compound wing, which is composed of three parts; a rectangular wing
in the middle and two reverse taper wings with an anhedral angle at the sides, is
investigated. This present research tries to reveal the effect of design parameters such
4
as, middle wing span, taper ratio, anhedral angle, ground clearance and Reynolds
number on the aerodynamic performance of the new compound wing configuration
in ground effect. Consequently by varying these design parameters, the different
aerodynamic characteristics of the compound wing could be obtained.
1.3 Research Objectives
The objectives of the present research are as follows:
i) To investigate aerodynamic characteristics of a new configuration
compound wing in ground effect.
ii) To investigate design parametric study of the compound wing related to
aerodynamic coefficients in proximity to the ground.
iii) To estimate approximately fuel consumption and CO2 emission
associated with the compound wing.
1.4 Scope of Study
The aim of the project is to investigate the aerodynamic characteristics of a
new compound wing in ground effect. This investigation have been done by
numerical and experimental methods which each one had several steps. The scopes
of this research work are as follows:
i) The literature review was carried out about aerodynamic characteristics of
various type of wing in proximity to the ground. This literature revealed
the current work of researchers about wing configuration and its
aerodynamic behaviour in ground effect. This step made a good guideline
for present research work.
5
ii) The CFD method was used for numerical analysis of the aerodynamic
characteristics of the compound wing. Three step, preprocessing, solving,
and post processing were discovered in CFD method.
• Preprocessing included designation of the wing model and the
computational domain, mesh generation, definition of fluid properties,
selecting the governing equations (turbulent model), and definition of
boundary condition of domain boundary.
• In solving, integration of the governing equations, discretisation of the
integral equations to find algebraic equations, and finally solution of
the algebraic equations by an iterative method have been determined.
• Discussion and analysis have been performed with plots and contours
of the results in post processing stage.
iii) Numerical simulations were performed with respect to main parameters
such as middle span and side span size, taper ratio, anhedral angle,
Reynolds number, ground clearance and angle of attack which they can
affect on aerodynamic performance of the compound wing.
iv) The aerodynamic forces of two wings, a rectangular wing and compound
wing have been measured by experiments in the low speed wind tunnel of
Universiti Teknologi Malaysia. The present experiments were carried out
with respect to different ground clearance, angle of attack and air
velocity. The aerodynamic forces directly were measured with a six
components balance system (JR3-50M31A3 sensor).
v) The test models were built by milling system. The material of wing
models was aluminium.
vi) The fuel consumption and CO2 emission related to aerodynamic forces
from numerical simulations have been obtained for a rectangular wing
and compound wings.
6
1.5 Significance of the study
The wide applicability of WIG craft such as civil and naval applications
makes a demand to investigate about wing in ground effect of this type of aircraft. It
has been recognized that the WIG crafts have special advantages for examples, cost
effectiveness, high ride quality in cruise mode, no need for airports or runways,
operating over any surfaces, water, land, snow and ice surface to use ground effect,
in addition, embarking the passenger on unprepared beach. Furthermore, the low fuel
consumption and environmental impact are other benefits of WIG craft compared to
airplane which they are favourable for economic and saving the green society. These
advantages makes a high demands to research on designation and operation of WIG
crafts to improve their performance and efficiency. The main part of WIG craft is its
wing, the present research focused on wing configuration in ground effect. The
results of this project will be useful for design of WIG craft to take a better support
from ground effect.
1.6 Organisation of Thesis
This thesis is divided into 7 chapters. In the first chapter, common
information such as objectives, scopes, and statement of problem of this research are
given. Additionally, the background of problem and the significant of this
investigation are provided. The next chapters (2-7) describe literature review,
research methodology, results and discussions, and conclusion and future work that
has been used for publishing in journals and presented in conferences.
Chapter 2 prepares a comprehensive literature review of available information
related to the topic of current research. This chapter includes numerical and
experimental simulation of aerodynamic characteristics of wings with various airfoil
sections and different wing configurations in close to the ground. In addition, the
flow behaviour around and behind the wings such as separation and wake region are
review. Also, this chapter contains some description about different type of WIG
7
crafts, and some systems such as power augmented ram (PAR) engine that increases
the performance of WIG craft.
In chapter 3, two research methods which are the computational and
experimental methods are described. The computational methodology consists of
turbulent models of flow around the wing, boundary layers and wall functions at near
wall, boundary conditions, solver, solutions controls such as discretization and
pressure-Velocity Coupling Method, and meshing. The experimental methodology
firstly gives a background about wind tunnel and introduces the low speed wind
tunnel of Universiti Teknologi Malaysia. Next, some descriptions are given about the
wing models, set-up of experiment and procedure of test.
A new compound wing is presented in chapter 4. The configuration of
compound wing is illustrated and shown in this chapter. The principal aerodynamic
coefficients of a compound wing and a rectangular wing are obtained by numerical
simulations. The aerodynamic coefficients of compound wing are compared with
rectangular one. The benefits of compound wings are described in proximity to the
ground.
The aerodynamic forces of a rectangular wing and a compound wing
configuration are experimentally measured in chapter 5. There are some comparisons
between rectangular wing and compound wing on aerodynamic coefficients respect
to different ground clearances, angle of attacks and free air velocities. The
advantages of compound wing in low ground clearance are described. Also, the
aerodynamic coefficients of both wings from present numerical simulations are
compared with experimental results.
In chapter 6 the design parametric study on aerodynamic characteristics of the
compound wing is numerically investigated in ground effect. The effects of principal
parameters such as span size of side wing, taper ratio and anhedral angle on
aerodynamics performance of compound wing are discovered. Moreover, the fuel
8
consumption and CO2 emission related to compound wings compared to rectangular
wing are explored.
Finally, the important conclusions are drawn in chapter 7 consistent with
results and discussion from the present research. Additionally, some future works are
recommended in this chapter.
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