THE AERODYNAMIC ANALYSIS OF BWB BASELINE II E5-8 UAV WITH CANARD ASPECT RATIO (AR) OF 8 AT ANGLE OF ATTACK OF 10 DEGREE AT 0.1 MACH NUMBER THROUGH CFD SIMULATION AT DIFFERENT CANARD SETTING ANGLES
MUHAMMAD NAZREEN BIN ZULKARNAIN (2008400848)
BACHELOR ENGINEERING (HONS) (MECHANICAL) UNIVERSITI TEKNOLOGI MARA (UiTM)
JULY 2012
“I/We declared that this thesis is the result of my/our own work except the ideas and summaries which I/We have clarified their sources. The thesis has not been accepted for any degree and is not concurrently submitted in candidature of any degree.”
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Muhammad Nazreen Bin Zulkarnain UiTM No : 2008400848
“I declared that I read this thesis and in our point of view this thesis is qualified in term of scope and quality for the purpose of awarding the Degree of Mechanical Engineering (Hons) Mechanical.”
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Supervisor or Project Advisor Prof. Dr. Wirachman Wisnoe Faculty of Mechanical Engineering MARA University of Technology (UiTM) 40450 Shah Alam Selangor
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Co- Supervisor Puan Zurriati Mohd. Ali Faculty of Mechanical Engineering MARA University of Technology (UiTM) 40450 Shah Alam Selangor
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Course Coordinator Wan Sulaiman Bin Wan Mohamad Faculty of Mechanical Engineering MARA University of Technology (UiTM) 40450 Shah Alam Selangor
Page Title
THE AERODYNAMIC ANALYSIS OF BWB BASELINE II E5-8 UAV WITH CANARD ASPECT RATIO (AR) OF 8 AT ANGLE OF ATTACK OF 10 DEGREE AT 0.1 MACH NUMBER THROUGH CFD SIMULATION AT DIFFERENT CANARD SETTING ANGLES
MUHAMMAD NAZREEN BIN ZULKARNAIN (2008400848)
A thesis submitted in partial fulfillment of the requirements for the award of Bachelor Engineering (Hons) (Mechanical)
Faculty of Mechanical Engineering Universiti Teknologi MARA (UiTM)
JULY 2012
i
ACKNOWLEDGEMENT
In the name of Allah the Most Gracious, Most Merciful, I would like to express my greatest gratitude for giving me the strength and patience to overcome the challenges and difficulties in completing this thesis and also for His Blessings. I would also like to express my sincere gratitude and appreciation to my supervisor and co-supervisor for their continuous support, generous guidance, patience and encouragement in the duration of the thesis preparation until its completion. I would also like to express my special thanks of gratitude to my project’s supervisor Prof Dr Wirachman Wisnoe as well as to my co-supervisor Puan Zurriati Mohd Ali who gave me the golden opportunity to do this great project and also for their continuous support, generous guidance, patience and encouragement in the duration of the thesis preparation until its completion. Last but not least, I also like to express my sincere gratitude and appreciation to my friends who helped me a lot when I am in difficulties in finishing this project. A million thanks to all who involved in this project. Thank you very much and may Allah bless all of you and repay your kindness.
ii
ABSTRACT
This thesis represented the study on aerodynamic of a Blended Wing Body (BWB) with canard aspect ratio of 8 for various canard angle of deflection at angle of attack 10° by using Computational Fluid Dynamics (CFD) software. The objectives of this project are to obtain the aerodynamics characteristic such as lift (CL), drag (CD), and pitching moment coefficient (CM); to analyze the result obtained through CFD simulation and to acquire the CFD visualization of pressure and Mach contour. The CAD design of BWB is obtained from the previous research and the design is modified with a rectangular canard placed in front of the main wing. The CAD format file is converted to parasolid format for it to be readable by NUMECA software. Generally, there are three stages of processes in NUMECA: pre-processing, processing and postprocessing. In NUMECA, Fine Hexpress is used as the mesher to acquire the appropriate mesh quality. Then, it use a solver for the CFD simulation process known as Fine Hexa by using Spalart-Allmaras turbulence model. The results are analyse by using CFView in order to obtain the pressure and Mach contour.
iii
TABLE OF CONTENT
Contents Page Title
i
ACKNOWLEDGEMENT
ii
ABSTRACT
iii
TABLE OF CONTENT
iv
LIST OF TABLES
vii
LIST OF FIGURES
ix
LIST OF ABBREVIATIONS
xii
1.
INTRODUCTION
1
1.1
Project Title
1
1.2
Project Background
2
1.3
Problem Statement
4
1.4
Objectives of Project
4
1.5
Significance of Project
4
1.6
Scope of Work
5 iv
1.7 2.
3.
4.
6
LITERATURE REVIEW
9
2.1
AERODYNAMICS ANALYSIS
2.2
CANARD
12
2.3
BLENDED WING BODY
12
2.4
ASPECT RATIO
14
2.5
MACH NUMBER
15
9
PARAMETER VALIDATION
16
3.1
Selection of Object
18
3.2
Computer Aided Design (CAD) Drawing
18
3.3
Computational Fluid Dynamics (CFD) Simulation
19
3.4
Summary
30
GRID SENSITIVITY STUDY
36
4.1
BWB Baseline-II E5 CAD Drawing
38
4.2
CFD Analysis with Variation of Grid Sensitivity
38
4.2.1
Initial Parameters
38
4.2.2
Grid Sensitivity Analysis
41
4.3
5.
Methodology
Final Parameter Settings
52
4.3.1
Box
52
4.3.2
Faceting
52
4.3.3
Initial Mesh
53
4.3.4
Number of Refinement
53
RESULT AND DISCUSSION 5.1
54
Aerodynamic Analysis for BWB Baseline-II E5-8
5.1.1
Result of BWB Baseline-II E5-8 CFD Simulation v
55 55
5.1.2
Coefficient of Lift, CL
56
5.1.3
Coefficient of Drag, CD
62
5.1.4
Coefficient of Pitching Moment, CM
64
5.1.5
Pressure Distribution
65
6.0
CONCLUSION AND RECOMMENDATION
67
6.1
Conclusion
68
6.2
Recommendation
68
7.0
REFERENCES
69
APPENDICES
72
APPENDIX A – CAD Drawing of BWB Baseline II E5-8
72
APPENDIX B – Velocity Vectors Flow Visualization
73
APPENDIX B1 – Velocity Vectors Flow Visualization
75
vi
LIST OF TABLES
TABLE
TITLE
PAGE
Table 3.1 Test condition for surrounding
26
Table 3.2 Test condition for BWB Baseline-II E2
27
Table 3.3 Wind tunnel and Numeca Data
30
Table 4.1 Box parameter
39
Table 4.2 Faceting parameter
39
Table 4.3 Initial mesh parameter
40
Table 4.4 Surrounding Condition
40
Table 4.5 BWB Baseline-II E5 Condition
40
Table 4.6 Variation of box
41
Table 4.7 Minimum length parameter
43
Table 4.8 Curve and Surface Tolerance parameter
45
Table 4.9 Curve Resolution parameter
46
Table 4.10 Surface Resolution parameter
48
Table 4.11 Initial Mesh parameter
49
Table 4.12 Types of Initial Mesh
49
Table 4.13 Number of Refinement parameter
50
Table 4.14 Box parameter
52 vii
Table 4.15 Faceting parameter
52
Table 4.16 Initial Mesh parameter
53
Table 4.17 Number of Refinement parameter
53
Table 5.1 Table of results for BWB Baseline-II E5-8
55
viii
LIST OF FIGURES
FIGURE
TITLE
PAGE
Figure 1.1 Motion of Aircraft about its Axes [6]
3
Figure 1.2 BWB-Baseline II E5 [5]
3
Figure 2.1 Aircraft Motion [17]
10
Figure 2.2 Forces in Aircraft [18]
11
Figure 2.3 BWB Baseline-I
13
Figure 2.4 BWB Baseline-II
13
Figure 2.5 BWB Baseline-II E2 without canard
13
Figure 2.6 Evolution of BWB in UiTM
14
Figure 3.1 BWB Baseline-II E2 [16]
18
Figure 3.2 Box size parameters
19
Figure 3.3 Position of BWB in the box.
19
Figure 3.4 Box with a hole of BWB Baseline-II E2 after subtracted
20
Figure 3.5 Domain Setting
20
Figure 3.6 BWB Baseline-II E2 with domain
20
Figure 3.7 Boundary Conditions Set up
21
Figure 3.8 Boundary conditions setting
21
Figure 3.9 Initial Mesh setting
22 ix
Figure 3.10 Global Paramaters under Mesh Adaptation
22
Figure 3.11 Surface Adaptation for local refinement number
23
Figure 3.12 Viscous layers setting
23
Figure 3.13 Finished mesh of BWB
24
Figure 3.14 Total number of cells
24
Figure 3.15 General properties setting
25
Figure 3.16: Fluid model setting.
25
Figure 3.17: Flow model parameters
26
Figure 3.18 Boundary conditions setting (solid)
27
Figure 3.19 Boundary conditions setting (external)
27
Figure 3.20 Initial solution setting.
28
Figure 3.21 Outputs setting.
29
Figure 3.22 Lift Coefficient, CL vs Angle of Attack, α
33
Figure 3.23: Drag Coefficient, CD vs Angle of Attack, α
34
Figure 4.1 L/D Ratio vs No of Cells (Box)
42
Figure 4.2 L/D Ratio vs Number of Cells (Min Length)
44
Figure 4.3 L/D Ratio vs Tolerance
45
Figure 4.4 L/D Ratio vs No of Cells (Curve Resolution)
47
Figure 4.5 L/D Ratio vs No of Cells (Surface Resolution)
48
Figure 4.6 L/D Ratio vs No of Cells (Initial Mesh)
50
Figure 4.7 L/D Ratio vs No of Cells (No of Refinement)
51
Figure 5.1 Lift Coefficient, CL versus Canard Setting Angle, δ
56
Figure 5.2 Mach number at δ = -11°, upper surface
57
Figure 5.3 Mach number at δ = -11°, bottom surface
57
Figure 5.4 Canard’s velocity vector at δ = -11°
58
Figure 5.5 Mach number contour at δ = -3°, upper surface
59
Figure 5.6 Mach number contour at δ = -3°,bottom surface
59
Figure 5.7 Canard’s velocity vectors at δ = -3°
60
Figure 5.8 Mach number contour at δ = 3°, upper surface
61
Figure 5.9 Mach number contour at δ = 3°, bottom surface
61
Figure 5.10 Canard’s velocity vectors at δ = 3°
62
x
Figure 5.11 Drag Coefficient, CD versus Canard Setting Angle, δ
63
Figure 5.12 Pitching Moment Coefficient, CM versus Canard Setting Angle, δ
64
Figure 5.13 Pressure contours at δ = -11° for upper (left) and lower (right) surfaces
65
Figure 5.14 Pressure contours at δ = -5° for upper (left) and lower (right) surfaces
65
Figure 5.15 Pressure contours at δ = -3° for upper (left) and lower (right) surfaces
65
Figure 5.16 Pressure contours at δ = 3° for upper (left) and lower (right) surfaces
66
xi
LIST OF ABBREVIATIONS
Re AR Ma V ρ c s F CL CD CM δ α
Reynold Number Aspect ratio Mach number speed of flow density chord span force lift coefficient drag coefficient pitching moment coefficient canard setting angle, degree angle of attack, degree
xii
CHAPTER I
1. INTRODUCTION
1.1
Project Title
The Aerodynamic Analysis of BWB Baseline II E5-8 UAV with Canard Aspect Ratio (AR) of 8 at Angle of Attack of 10 degree at 0.1 Mach Number through CFD Simulation at Different Canard Setting Angles.
1
1.2
Project Background
In aircraft, there are two motions that are involve which are translational and rotational motion. The translational motion is the relative linear position from the origin. Rotational motion relates to the orientation of the body which consists of yawing, pitching and rolling [1]. These motions are influenced by the control surfaces; ailerons (rolling), elevator (pitching) and rudder (yawing) [2]. The pitching motion or longitudinal motion is influenced by the elevator or canard [3]. Canard is a longitudinal stabilizer located ahead of the main wing, on the fuselage. There are three types of canard; lifting canard, control canard and couple canard. However, this project will focus on control canard. Control canard provides the same function as the aft horizontal stabilizer by introducing a moment that changes the angle of attack of fuselage and main wing [4]. From the previous aerodynamics analysis data obtained, the BWB-Baseline II shows a better result rather than Baseline-I, therefore UITM has continued their study on Baseline-II until now which is BWB Baseline-II E5 [5]. The BWB-Baseline II E5-8 will use a rectangular canard as a secondary wing and the primary wing tip will be twisted a little. The aerodynamics analysis data in this project will be obtained using CFD.
2
Figure 1.1 Motion of Aircraft about its Axes [6]
Canard
Twisted wing
Figure 1.2 BWB-Baseline II E5 [5]
3
1.3
Problem Statement
There are a few setbacks in this project since the data is not available for the aerodynamic analysis (lift coefficient CL, drag coefficient CD, and pitching moment coefficient CM) of the BWB Baseline II E5-8. Furthermore, this project is a new research to study the effect of a rectangular canard on the BWB Baseline II E5.
1.4
Objectives of Project
This project consists of several objectives which are: 1. To obtain lift, drag and pitching moment coefficient. 2. To analyze the result obtained through the CFD simulation. 3. To obtain CFD visualization: pressure and Mach countour, velocity vectors.
1.5
Significance of Project
The significance of this project is obtaining the aerodynamics data for BWBBaseline II E5-8 for analyzing the aerodynamic characteristics. Furthermore, the result from this project can also be included in the database for BWB-Baseline II E5-8.
4
1.6
Scope of Work
This project consists of several scopes of work which are: 1. Model to be used: BWB-Baseline II E5-8 2. Type of Canard to be used: Rectangular Canard with Aspect Ratio (AR) 8 [Area = 0.36 m2] 3. Canard setting angle : -22° to 8° 4. Mach Number 0.1 5. CFD simulation 6. Turbulence models to be use : Spalart-Allmaras turbulence model
5
1.7
Methodology
START
Literature review
PARAMETER VALIDATION Model Selection
CAD Drawing
CFD Simulation
Reference from
Data
journals/article
Validate
NO
? YES
GRID SENSITIVITY STUDY Obtain BWB-Baseline II E5-8 CAD Drawing
CFD Analysis with variation of grid sensitivity, N
Independence achieved? YES
6
NO
BWB –BASELINE II E5-8 CFD ANALYSIS
Turbulence Model: Spalart-Allmaras
Result Analysis
END
7
Literature Review To gain basic knowledge on aerodynamic analysis, canard, Blended Wing Body (BWB) and previous research on books and journals that may help to develop the project. Literature review will be done throughout the project. Parameter Validation Search for any suitable flying model such as wing blade or aerofoil. Then, draw the model in CAD drawing and do CFD simulation. Next, is to validate the data obtained from the simulation with the data from the reference journals and books. If the obtained data is inaccurate with the data from the references, repeat the CFD simulation. Grid Independence Study The CAD drawing for BWB-Baseline II E5-8 and rectangular canard with aspect ratio of 8 are obtained. The model for BWB-Baseline II E5-8 is the half model of the structure which is to reduce the simulation time by reducing the computer’s memory and saving time in modeling. Next, the CAD drawing is transferred to CFD to generate meshing. The analysis will be done by using different meshing sizes to test the L/D ratio. This process will continue until the L/D ratio approach to constant at certain no of grid, N. BWB –Baseline II E5-8 CFD Analysis Then, the process is continued for the aerodynamic analysis section. SpalartAllmaras will be use as the turbulence model at the angle of attack 10° with different canard setting angles from δ = -22° to δ = 8°. The result will be obtained through the CFD simulation and graph will be plot where the CL, CD, and CM versus the different canard setting angle at angle of attack 10°. Then, by using the CFView, we can get the pressure and Mach contour and also velocity vectors. The data from the CFD simulation will be analyze and the result will be discussed together with the velocity vectors, pressure and Mach contour.
8
CHAPTER II
2. LITERATURE REVIEW
2.1
AERODYNAMICS ANALYSIS
2.1.1
Aircraft motion
Aircraft consist of three motions which are pitching, rolling and yawing motions about the center of gravity of the aircraft. Pitching motion is the movement of the aircraft about its pitch axis. This longitudinal motion is influenced by the elevator and/or canard which act as its control surface. Rolling and yawing motions are the movement about its roll and yaw axes respectively. Ailerons are the control surface that influenced the rolling motion of the aircraft while rudder is the control surface for yawing motion.
9
Figure 2.1 Aircraft Motion [17]
10
2.1.2
Aircraft Forces
Mainly, there are four forces acted on an aircraft. These forces that are exerted on the aircraft are lift, thrust, drag and weight forces. Lift force is the sum of components of the pressure and wall shear forces in the direction normal to the flow tend to move the body in that direction [7].
Drag on the other hand, is the force that acts in a direction that is opposite to the motion of the aircraft. Drag is a vector quantity which has magnitude and direction [7].
Figure 2.2 Forces in Aircraft [18]
11
2.2
CANARD
Canard is a longitudinal stabilizer which is located ahead of the primary wing and on the fuselage [8]. For high performance aircraft, canard-wing configuration is often required for this type of aircraft design which it need to provide high lift for wide range of angles of attack in order for it to be maneuverable [9]. There are three types of canard which are control canard, lifting canard and couple canard. Control canard will be use in this project which act as the secondary wing and it provide the same function as the front horizontal stabilizer by introducing a moment that changes the angle of attack of the fuselage as well as the main wing [10].
2.3
BLENDED WING BODY
Blended Wing Body (BWB) is a concept which was introduced by Liebeck et. al [11]. Blended Wing Body is a concept where the fuselage and wing is combined together to form a single body [12]. BWB is a hybrid of flying-wing aircraft and the conventional aircraft where the body is designed to have a shape of an airfoil and carefully streamlined with the wing to have a desired planform [13].
2.2.1
History of BWB in UiTM
In University of Technology MARA (UiTM), the research on Blended Wing Body has been started since 2005. The UiTM’s BWB has been classified as a mini UAV (Unmanned Aerial Vehicle). There are many types of BWB which are developed by UiTM for research purposes which are BWB Baseline-I and BWB Baseline-II. BWB Baseline-I is designed with an elevator for pitching motion. BWB Baseline-II 12
completely revised version from BWB Baseline-I. It has a simpler planform, broader chord wing and slimmer body compared to BWB Baseline-I. BWB Baseline-II E2 without canard has a slight modification where part of the wing is twisted down at certain angle [5][14].
Figure 2.3 BWB Baseline-I
Figure 2.4 BWB Baseline-II
Figure 2.5 BWB Baseline-II E2 without canard
13
Figure 2.6 Evolution of BWB in UiTM Blended Wing Body Baseline-II E5 is a type of BWB with a part of its primary wing is twisted downward at a certain angle and a rectangular canard as its secondary wing which is placed in front of the primary wing.
2.4
ASPECT RATIO
Aspect Ratio is a measure of how long and slender a wing is from tip to tip. The Aspect Ratio of a wing is defined to be the square of the span divided by the wing area and is given the symbol AR [15].
Setting angle is the angle which the canard is set with respect to its horizontal axis.
14
2.5
MACH NUMBER
Where c = 346 m/s in air at room temperature at sea level. A flow is called sonic when Ma = 1, subsonic when Ma < 1, supersonic Ma > 1 and hypersonic when Ma >> 1.
15
CHAPTER III
3. PARAMETER VALIDATION
In this chapter, Parameter Validation will be discussed briefly. Parameter Validation is a process of running a simulation on a selected object with the valid data as reference from journals. The data that are obtained from the simulation will be compared to the data in the journal. The main idea of this stage is to obtain the values of lift coefficient (CL), drag coefficient (CD) and pitching moment (CM) (any which that are provided in the journal) that is as near as possible to the data from the referred journal.
16
START
Literature review
PARAMETER VALIDATION Model Selection
CAD Drawing
CFD Simulation
Reference from
Data
journals/article
Validate ?
GRID SENSITIVITY
17
NO
3.1
Selection of Object
In order to proceed with the simulation of Computational Fluid Dynamics (CFD), an object must be selected with a valid data from journal to compare the values of lift coefficient (CL), drag coefficient (CD) and pitching moment (CM) (any which data that is provided). In this project, a Blended Wing Body (BWB) Baseline-II E2 as shown in figure below is selected as the object for the parameter validation. The data for this BWB Baseline-II E2 is obtained from the journal “The Aerodynamic Performance of Blended Wing Body Baseline-2 E2” [16]. The values of CL and CD from this journal will be compared to the values obtained through the CFD simulation with NUMECA software.
Figure 3.1 BWB Baseline-II E2 [16]
3.2
Computer Aided Design (CAD) Drawing
The CAD drawing of the BWB Baseline-II E2 is converted to parasolid format (.x_t) in which SolidWorks software is used. The purpose of the CAD drawing converted to parasolid format is for it to be readable by NUMECA software.
18
3.3
Computational Fluid Dynamics (CFD) Simulation
The Computational Fluid Dynamics (CFD) Simulation will be done by using NUMECA Software.
1. The box is created to define the boundary conditions. The BWB is placed in the middle of the box.
Figure 3.2 Box size parameters
Figure 3.3 Position of BWB in the box. 2. The box is then subtracted with the BWB body and the domain is created.
19
Figure 3.4 Box with a hole of BWB Baseline-II E2 after subtracted
Figure 3.5 Domain Setting
Figure 3.6 BWB Baseline-II E2 with domain 20
3. The boundary conditions are defined to mirror, external and solid.
Figure 3.7 Boundary Conditions Set up
Figure 3.8 Boundary conditions setting
4. Mesh Wizard a. Initial Mesh: This setting will affect the number of cells. 21
Figure 3.9 Initial Mesh setting b. Adapt to geometry
Figure 3.10 Global Paramaters under Mesh Adaptation
22
Figure 3.11 Surface Adaptation for local refinement number
c. Snap to geometry: No changes are needed for this part. d. Optimize: No changes are needed for this part. e. Viscous layers
Figure 3.12 Viscous layers setting
23
Figure 3.13 Finished mesh of BWB
Figure 3.14 Total number of cells
5. The meshing file is saved to .igg file. Meshing program need to be close first to proceed to HEXSTREAM. 6. The mesh file is loaded automatic in computation program. 7. The general properties are set.
24
Figure 3.15 General properties setting
8. Fluid model is set by selecting the air (perfect gas) (refer to test condition).
Figure 3.16: Fluid model setting.
25
9. Flow model is set.
Figure 3.17: Flow model parameters
10. No changes are done in solid model, rotating machinery and heat source. 11. The boundary conditions are set according to the information given from reference. Table 3.1 Test condition for surrounding Atmospheric pressure, Patm
100424 Pa
Air temperature, Tair
25°C / 298K (average)
Air density, ρair
1.165 kg/m3
Air kinematic viscosity, νair
m2/s
Air velocity, Vair
35 m/s
26
Table 3.2 Test condition for BWB Baseline-II E2 Reference length, Lref
0.114 m
Reference area, Sref
0.03995 m2
Figure 3.18 Boundary conditions setting (solid)
Figure 3.19 Boundary conditions setting (external) 27
12. Initial solution is set. The value of velocity in x and y direction is the resolve velocity of 35m/s about the angle of attack.
Figure 3.20 Initial solution setting.
13. Numerical schemes 14. Output: The direction of lift and drag depends on the position of the solid.
28
Figure 3.21 Outputs setting.
15. Control Variable: The iteration set to 1000, the solver will complete when reach 1000 or will complete when the graph is converge. 16. No changes at Launching mode and Ansys output. 17. Before the simulation start, the solver needs to be saved. After that, the simulation will run. 18. Obtain result from the software. The time to complete the simulation depends on the meshing cells. More meshing cells are use, more time is required.
29
3.4
Summary
In this study, various angles of attack have been simulated between -20° to 46° at Mach 0.1 (35 m/s) by using Spalart-Allmaras turbulence model.
Table 3.3 Wind tunnel and Numeca Data No.
Pitch
CD(exp)
CL(exp)
CD(CFD)
CL(CFD)
(deg.)
Percentage Difference (%) CD
CL
1
-20
0.2098
-0.5555
0.2110
-0.5787
0.54
4.17
2
-16
0.1416
-0.4809
0.1670
-0.5825
17.96
21.12
3
-14
0.1070
-0.4659
0.1362
-0.5305
27.27
13.85
4
-12
0.0726
-0.4447
0.1030
-0.4669
41.81
4.99
5
-10
0.0560
-0.3617
0.0759
-0.3694
35.35
2.13
6
-9
0.0504
-0.3088
0.0646
-0.3116
28.10
0.90
7
-8
0.0431
-0.2438
0.0545
-0.2468
26.30
1.21
8
-7
0.0356
-0.1783
0.0469
-0.1830
31.57
2.59
9
-6
0.0296
-0.1110
0.0411
-0.1185
38.85
6.82
10
-5
0.0256
-0.0475
0.0368
-0.0522
43.73
10.00
11
-4
0.0232
0.0214
0.0340
0.0163
46.63
23.54
12
-3
0.0215
0.0916
0.0327
0.0830
51.93
9.47
13
-2
0.0197
0.1533
0.0328
0.1513
66.16
1.27
14
-1
0.0185
0.2109
0.0343
0.2179
84.87
3.33
15
0
0.0181
0.2644
0.0372
0.2834
105.83
7.21
16
1
0.0180
0.3171
0.0294
0.3480
62.93
9.74
17
2
0.0186
0.3676
0.0294
0.3480
57.64
5.34
18
3
0.0186
0.4177
0.0545
0.4704
193.76
12.61
19
4
0.0200
0.4626
0.0631
0.5247
215.30
13.43
30
20
5
0.0212
0.5050
0.0735
0.5755
245.95
13.95
21
6
0.0234
0.5453
0.0854
0.6184
265.56
13.41
22
8
0.0341
0.6022
0.1166
0.6691
242.09
11.11
23
9
0.0892
0.5634
0.1312
0.6862
47.06
21.78
24
10
0.1105
0.5545
0.1475
0.7134
33.52
28.67
25
11
0.1304
0.5679
0.1662
0.7330
27.49
29.07
26
14
0.1749
0.6211
0.2293
0.8075
31.09
30.00
27
18
0.2477
0.6845
0.3097
0.8695
25.04
27.04
28
22
0.3269
0.7500
0.4025
0.9332
23.13
24.44
29
26
0.4228
0.8351
0.4933
0.9713
16.67
16.31
30
30
0.5109
0.8716
0.5856
0.9962
14.63
14.30
31
34
0.6100
0.9060
0.6846
1.0094
12.23
11.41
32
36
0.6589
0.9156
0.7386
1.0141
12.10
10.76
33
40
0.7665
0.9378
0.8372
1.0004
9.22
6.67
34
42
0.8226
0.9452
0.8819
0.9823
7.21
3.93
35
44
0.8699
0.9395
0.9180
0.9522
5.53
1.35
36
46
0.9244
0.9356
0.9180
0.9522
0.69
1.77
31
1.
Lift Coefficient, CL analysis From Figure 3.22, it shows the comparison result between CFD simulation and
experimental data for BWB Baseline-II E2. The lift curves show a trend that are similar to the linear region (α = -10° to 8°) although at α = 2°, there is a slight drop since the percentage of error at that specific angle of attack is 5.34% which is approaching the experimental data. However, at α = 3° the percentage of error increased to 12.61% and it continue to increase linearly till α = 8°. The graph has a curve that is slightly similar to the experimental result. At α = 44° and 46°, the value of lift coefficient is nearly as the experimental result with percentage of error 1.35% and 1.77% respectively. 2.
Drag Coefficient, CD analysis As shown in Figure 3.23, the graph of CFD simulation shows a trend
line that is roughly similar to the data obtained from wind tunnel test. The trend line moves nearly to the experimental data. However, at α = 3°, the line moves away from the experimental data with the increasing percentage of error. At α = 9°, the line moves along the experimental data with a significant distance separating them. The data from CFD simulation is almost the same with the experimental
data
at
α
=
46°
with
32
its
percentage
of
error
0.64%.
1.2 1.0 0.8
Lift Coefficient, CL
0.6 0.4 Clexp
0.2
CL
0.0 -20
-14
-10
-8
-6
-4
-2
0
2
4
6
9
11
-0.2 -0.4 -0.6 -0.8
Angle of Attack, α (°)
Figure 3.22 Lift Coefficient, CL vs Angle of Attack, α
33
18
26
34
40
44
1.0 0.9
0.8
Drag Coefficient, CD
0.7 0.6 0.5
Cdexp CD
0.4 0.3 0.2 0.1 0.0
-20
-14
-10
-8
-6
-4
-2
0
2
4
6
9
11
18
Angle of Attack, α (°)
Figure 3.23: Drag Coefficient, CD vs Angle of Attack, α
34
26
34
40
44
The investigation on aerodynamic characteristics data obtained from CFD simulation and wind tunnel test, shows that the curve of the graph for both lift and drag coefficient are slightly similar to each other although there is a signicant percentage of error with 30% of error at α = 14° for lift coefficient and 265% of error at α = 6° for drag coefficient. The smallest percentage of error for lift coefficient is 0.9% at α = -9° as for drag coefficient, 0.54% of error at α = -20°.
35
CHAPTER IV
4. GRID SENSITIVITY STUDY
Proceeding from the Parameter Validation, the next chapter is to carry out the Grid Sensitivity study. Grid Sensitivity study is the stage of obtaining the most suitable parameter setting that will be use for the simulation using NUMECA. In order to proceed with this stage, some parameters will be taken into account that will be vary accordingly to obtain the most suitable parameter setting to be use for the BWB Baseline-II E5-8 CFD Simulation purposes.
36
START
Literature review
Parameter Validation GRID SENSITIVITY STUDY STUDY Obtain BWB-Baseline II E5-8 CAD Drawing
CFD Analysis with variation of grid sensitivity
Independence achieved? YES
BWB Baseline-II E5-8 CFD Simulation
37
NO
4.1
BWB Baseline-II E5 CAD Drawing
The CAD drawing of the BWB Baseline-II E5 and rectangular canard with aspect ratio of 8 will be obtained. However, in this chapter, only the drawing of the half body BWB Baseline-II E5 will be use for the CFD simulation. The drawing of rectangular canard will be use in the next chapter. The purposes of using the half body of BWB Baseline-II E5 are to reduce the simulation time by reducing the computer’s memory usage and saving time in modeling [19].
4.2
CFD Analysis with Variation of Grid Sensitivity
The drawing of the half body BWB Baseline-II E5 is then import to CFD to generate the meshing. The analysis will be done by varying the values for selected parameters to obtain a fine mesh and to test the CL, CD and L/D ratio. The process will stop when the CL, CD, and L/D is approaching to constant at certain number of grid. There are mainly four parameters that will be vary to obtain the most suitable parameter settings which are, (1) Box; (2) Initial Mesh; (3) Faceting; and (4) Number of Refinement.
4.2.1
Initial Parameters
In order to run the simulation process for grid sensitivity study, a benchmark parameter setting will be used. For example, when the parameter for the box is to be 38
vary as to obtain the L/D ratio is approaching to constant number of grid, the other parameters setting for initial mesh, faceting and number of refinement will be based on the benchmark parameters.
4.2.1.1 Box
Table 4.1 Box parameter
FIRST CORNER OPPOSITE CORNER
X
Y
Z
-40
-50
0
62
50
-50
4.2.1.2 Faceting
Table 4.2 Faceting parameter
Minimum length
Used
Default
0.0084
8.4
0.84
84
0.00042
4.2
0.00042
4.2
3
20
3
20
Maximum length Curve tolerance Surface tolerance Curve resolution Surface resolution 39
4.2.1.3 Initial Mesh
Table 4.3 Initial mesh parameter Used
Default
X axis
30
12
Y axis
24
12
Z axis
12
6
4.2.1.4 Number of Refinement
Number of refinement = 10
4.2.1.5 Test Condition for Surrounding and BWB Baseline-II E5
Table 4.4 Surrounding Condition Atmospheric pressure, Patm
101325 Pa
Air temperature, Tair
24°C / 297K (average)
Air density, ρair
1.165 kg/m3
Air kinematic viscosity, νair
m2/s
Air velocity, Vair
35 m/s
Table 4.5 BWB Baseline-II E5 Condition Reference length, Lref
0.658 m
Reference area, Sref
2.641 m2 (full body) 40
1.1642 kg/m3
Reference volumic mass, ρref
4.2.2
Grid Sensitivity Analysis
From the above parameters, the simulation for the grid sensitivity study can proceed by running simulation for various types of setting.
4.2.2.1 Box There are various types of box setting that are use for this grid sensitivity. This study will start by using the smallest box to the biggest possible size of box. The next step is to obtain the lift, drag and pitching moment coefficient through simulation. The number of cells will be taken into account as it is the criteria in determining the suitable parameter setting. Table 4.6 Variation of box BOX SCALE
X
1.5 X
2.0 X
1
2
3
2.5 X
4
3.0 X
5
3.5 X
4.0 X
6
7
RESULTS
MESH
Box Size
Box No
INITIAL
Corner
X
Y
Z
1st
-20
-20
0
2nd
20
20
-20
1st
-30
-30
0
2nd
30
30
-30
1st
-40
-40
0
2nd
40
40
-40
1st
-50
-50
0
2nd
50
50
-50
1st
-60
-60
0
2nd
60
60
-60
1st
-70
-70
0
2nd
70
70
-70
1st
-80
-80
0
2nd
80
80
-80
NO OF CELL
X
Y
Z
CL
CD
CM
4
4
2
0.3104
0.0312
-0.1402
399,515
6
6
3
0.3137
0.0314
-0.1422
384,038
8
8
4
0.3110
0.0310
-0.1407
400,332
10
10
5
0.3114
0.0309
-0.1410
386,789
12
12
6
0.3152
0.0312
-0.1432
384,795
14
14
7
0.3137
0.0310
-0.1426
400,937
16
16
8
0.3162
0.0310
-0.1439
386,262
41
TIME
1H 26Min 2H 34Min 1H 35Min 1H 15Min 1H 21Min 1H 23Min
10.7 10.6
L/D Ratio
10.5 10.4 L/D vs nb
10.3 10.2 10.1 384038 384795 386262 386789 399515 400332 400937 Number of Cells, nb
Figure 4.1 L/D Ratio vs No of Cells (Box)
From the graph above which is obtained from the simulation, it can be observed that at number of cells 386789, the L/D is approaching to constant. As a result, the parameter at number of cells 386789 with box setting number 4 can be use for the BWB Baseline-II E5 simulation with installed canard.
42
4.2.2.2 Faceting
Faceting is the step which allows the user to adjust the parameters to control the creation of the triangulation of any selected body which in this case is the BWB Baseline-II E5. In order to modify the setting in faceting, there are several parameters that should be considered. The parameters that are involved: (1) minimum length; (2) maximum length; (3) curve and surface tolerance; (4) curve and surface resolution.
4.2.2.2.1 Minimum Length The minimum length can be described as the minimum edge length of the triangulation facets. In order to modify the setting for these parameters, the default value for minimum length will be divided by certain value for the variation purpose of the parameter setting. Then the value will be use to run the simulation and to obtain the suitable parameter by L/D ratio approaching to constant number of cells to be use for the simulation with rectangular canard.
Table 4.7 Minimum length parameter Divide
No
No
CL
CD
CM
300
0.023
0.3088038
0.025474
-0.14105
2141888
500
0.014
0.3107841
0.025206
-0.14241
2142831
700
0.01
0.3111304
0.025012
-0.14279
2143029
1000
0.007
0.3124449
0.02466
-0.1437
2143305
1300
0.00539
0.3123701
0.024698
-0.14361
2143144
1500
0.00467
0.312177
0.024773
-0.14352
2143305
By
43
Cells
18.00 16.00 14.00
L/D Ratio
12.00 10.00 8.00
L/D vs nb
6.00 4.00 2.00 0.00 2141888 2142831 2143029 2143305 2143144 2143305 Number of Cells, nb
Figure 4.2 L/D Ratio vs Number of Cells (Min Length)
From the graph above, from number of cell 2141888, the graph stays constant until 2143029. At that point, the graph increase and from number of cell 2143305, the value of L/D ratio stays constant onwards. Therefore, the chosen parameter for minimum length is 0.007 which is at the number of cell 2143305.
4.2.2.2.2 Maximum Length
Maximum length is the maximum edge length of the triangular facets. The default value will be automatically computed by the system. For this parameter setting, the default value for maximum length will be divided by 100. When the default value is divided by 1000, the processing time appears to be longer and may cause computer to hang. It is unnecessary to divide the default value to obtain a smaller length for the maximum length.
44
4.2.2.2.3 Curve and Surface Tolerance
Curve chordal tolerance is the distance that is maximum between a curve with the corresponding triangulation edges. As for surface plane tolerance, it described the distance tolerance in model units between a surface and the triangulation. For both curve and surface tolerance it is best to divide the default value by 100. However, it can be fine tuned to obtain the most suitable parameter for simulation of BWB Baseline-II E5 with rectangular canard.
Table 4.8 Curve and Surface Tolerance parameter Tolerance
CL
CD
CM
1000
0.33
0.016
-0.1521
5000
0.33
0.016
-0.1532
10000
0.33
0.017
-0.1524
22.0 21.0
L/D Ratio
20.0 19.0 L/D vs tolerance 18.0 17.0 16.0 0
2000
4000
6000
8000
10000
12000
Tolerance
Figure 4.3 L/D Ratio vs Tolerance
45
From the graph of L/D ratio against tolerance above, the value of L/D can be observed constant at tolerance 1000 until 5000. However, this value drops at tolerance 10000. Therefore, the most suitable parameter to be use can be determined at tolerance 1000.
4.2.2.2.4 Curve and Surface Resolution
Curve Resolution Curve resolution is referred to the maximum angle between the curve and its triangulation edges. A smaller maximum angle between the curve and its triangulation edges may give a more accurate result. For this grid sensitivity study purpose, the curve resolution will be vary to obtain the of L/D ratio that is approaching constant number of cells. Table 4.9 Curve Resolution parameter Curve
CL
CD
L/D
No of Cells
4
0.28
0.03
9.33
2143231
6
0.3
0.03
10.00
2142703
8
0.3
0.03
10.00
2141697
10
0.3
0.03
10.00
2140987
12
0.3
0.03
10.00
2141453
16
0.3
0.03
10.00
2141837
20
0.31
0.02
15.50
2141297
Resolution
46
18 16
L/D Ratio
14 12 10 8 6
L/D vs nb
4 2 0
Number of Cells, nb
Figure 4.4 L/D Ratio vs No of Cells (Curve Resolution)
From the graph above, the value of L/D fluctuated from number of cell 2140987 to 2141453. From L/D at number of cell 2141453, the L/D ratio value moves in a constant manner and decrease at number of cell 2143231. The chosen parameter for curve resolution is 6. Although the curve resolution of 6 is not at the point where the L/D ratio is approaching to constant number of cells, however it is still in the region where the L/D is constant despite the number of cells is slightly higher 2142703 which does not give any significance different compared to curve resolution at 12 with number of cells 2141453.
Surface Resolution Surface resolution is the angular tolerance between the surface and its triangulation. A lower angular tolerance may give a more accurate triangulation.
47
Table 4.10 Surface Resolution parameter Surface
NO. OF
CL
CD
L/D
4
0.31
0.02
15.50
2142508
7
0.31
0.02
15.50
2142519
8
0.31
0.02
15.50
2142460
10
0.31
0.03
10.33
2142428
13
0.31
0.02
15.50
2142524
Resolution
CELLS
18 16
L/D Ratio
14 12 10 8 6
L/D vs nb
4 2 0
Number of cells, nb
Figure 4.5 L/D Ratio vs No of Cells (Surface Resolution)
Referring to the graph above, at number of cell 2142428, the L/D ratio is increasing to number of cell 2142460. At this point onwards, the value for L/D ratio is constant. The chosen surface resolution is 7 which it is still in the constant region of the graph despite the insignificantly number of cell difference between the surface resolution at 4.
48
4.2.2.3 Initial Mesh
The initial mesh is the crucial part that gives a large effect to the number of cells. As the number of mesh increases, the number of cells will also increase. Therefore, in order to obtain a lower number of cells in order to save time during meshing, the number of mesh should be lower. With a higher number of cells, the mesh quality would be finer.
Table 4.11 Initial Mesh parameter No. of
Mesh
CL
CD
L/D
Mesh 1
0.3265
0.0164
19.97
1080
Mesh 2
0.3243
0.0163
19.94
2560
Mesh 3
0.3271
0.0170
19.21
5000
Mesh 4
0.3266
0.0163
19.98
8640
Mesh 5
0.3250
0.0159
20.47
13720
Mesh 6
0.3242
0.0163
19.84
20480
Mesh 7
0.3251
0.0154
21.05
29160
Mesh 8
0.3270
0.0170
19.18
40000
Mesh 9
0.3270
0.0166
19.75
53240
Mesh 10
0.3268
0.0164
19.97
69120
Cells
Table 4.12 Types of Initial Mesh Mesh
Mesh
Mesh
Mesh
Mesh
Mesh
Mesh
Mesh
Mesh
Mesh
1
2
3
4
5
6
7
8
9
10
X axis
15
20
25
30
35
40
45
50
55
60
Y axis
12
16
20
24
28
32
36
40
44
48
Z axis
6
8
10
12
14
16
18
20
22
24
49
16.6 16.5
L/D Ratio
16.4 16.3 16.2
L/D vs nb
16.1 16 15.9 0
20000
40000
60000
80000
Number of Cells, nb
Figure 4.6 L/D Ratio vs No of Cells (Initial Mesh)
Graph above shows L/D ratio against number of cells. It can be observed that the graph is fluctuating until at number of cell 40000, the L/D ratio is approaching to constant number of cells. At this point, the parameter to be use for simulation of BWB Baseline-II E5 with rectangular canard can be determined.
4.2.2.4 Number of Refinement
The number of refinement is use to adjust the quality of the mesh. A higher number of refinements, the quality of the mesh will be finer. However, when the number of the refinement increase, the number of cells will also increase.
Table 4.13 Number of Refinement parameter No of Refinement 7
CL
CD
CM
0.3173
0.0392
-0.1436
50
No. of Cells 222772
L/D 8.09
8
0.3168
0.0288
-0.1456
619581
11.00
9
0.3135
0.0254
-0.1443
1841955
12.36
10
0.3135
0.0254
-0.1443
1841955
12.36
11
0.3135
0.0254
-0.1443
1841955
12.36
12
0.3135
0.0254
-0.1443
1841955
12.36
13
0.3135
0.0254
-0.1443
1841955
12.36
14 12
L/D Ratio
10 8 6 L/D Ratio vs No of Cells, nb
4 2 0
Number of Cells, nb
Figure 4.7 L/D Ratio vs No of Cells (No of Refinement)
Referring to the above graph of L/D ratio against number of cells, as the number of cells increases, the L/D ratio is also increases until it reach number of cells 1841955. From number of cells of 1841955 onwards, the L/D ratio is constant. At number of cells 1841955, the number of refinement is 9. Therefore, it can be choose as the parameter to be use for the simulation of BWB Baseline-II E5 with rectangular canard.
51
4.3
Final Parameter Settings
After running the simulation for the grid sensitivity study, it can be come to a consideration for the parameter setting that will be use for the simulation of BWB Baseline-II E5 with a rectangular canard which will be use in the next chapter.
4.3.1
Box Table 4.14 Box parameter
PARAMETER FIRST CORNER
VALUE X
Y
Z
-50
0
-50
50
50
50
OPPOSITE CORNER
4.3.2
Faceting Table 4.15 Faceting parameter PARAMETER
VALUE
min length
0.007
max length
/100
curve tolerance
/1000
surface tolerance
/1000
curve resolution
6
surface resolution
7
52
4.3.3
Initial Mesh
The parameter value for initial mesh use to run simulation of BWB BaselineII E5 with rectangular canard is not the same from value stated before. The initial mesh depends on the size of the box, since the current box that will be use for the simulation of BWB Baseline-II E5-8 is not similar to the box used for grid sensitivity study. Therefore, the value of the initial mesh is changed to reduce the number of cells of the box. Although the number of mesh for the box is less, the number of mesh near the body can be increase from the target cell size at the refinement to have more mesh near the body of BWB Baseline-II E5 together with rectangular canard.
Table 4.16 Initial Mesh parameter VALUE
PARAMETER
Size of Cube
4.3.4
X axis
10
Y axis
5
Z axis
10
Number of Refinement Table 4.17 Number of Refinement parameter PARAMETER
VALUE
No of
9
Refinement Target cell size
0.01,0.01,0.01
53
CHAPTER V
5. RESULT AND DISCUSSION
This chapter will discuss the result that is obtained from the simulation of the BWB Baseline-II E5-8 with rectangular canard aspect ratio of 8 at various canard setting angles, δ, at angle of attack, α = 10° by using the steps and parameters as mentioned in the previous chapter. The obtained data will be tabled and the graph of lift, drag and pitching moment coefficient (CL, CD, and CM) will be plotted against the canard setting angle. The aerodynamic characteristics from the result will be discuss by taking into account the pressure and Mach contour as well as the velocity vectors.
54
5.1
Aerodynamic Analysis for BWB Baseline-II E5-8
The simulation process for BWB Baseline-II E5-8 is done at angle of attack 10° with various canard setting angles. For this project purposes, the deflection angles of canard is taken from δ = -22° to δ = 8°. From the collected data, the lift, drag and pitching moment coefficient (CL, CD and CM) of the BWB Baseline-II E5-8 can be discussed.
5.1.1
Result of BWB Baseline-II E5-8 CFD Simulation
Table below shows the data obtained from the CFD Simulation. The data of lift coefficient, CL, drag coefficient, CD and pitching moment, CM are collected and recorded in the table as below. Table 5.1 Simulation results of BWB Baseline-II E5-8 Canard
Lift
Setting
Coefficient,
Angle, δ
CL
-22
0.6238
0.1676
-0.3246
-17
0.6892
0.1734
-0.3128
-14
0.7526
0.1552
-0.2650
-11
0.7886
0.1643
-0.2282
-8
0.7523
0.1367
-0.1254
-6
0.7228
0.1430
-0.0862
-3
0.7573
0.1485
-0.0847
0
0.7518
0.1562
-0.0901
3
0.7399
0.1630
-0.0652
6
0.7250
0.1645
-0.0708
8
0.7215
0.1664
-0.0507
Drag Coefficient, CD
55
Pitching Moment Coefficient, CM
5.1.2
Coefficient of Lift, CL
Figure 5.1 below shows the graph of lift coefficient, CL against the canard setting angle, δ at angle of attack 10°. From the graph, it can be observed that at δ = -22°, the lift coefficient value is also increasing. However, at the δ = -11° the lift coefficient value decrease until δ = -6°. Further increase of the canard setting angle, increase the value for lift coefficient. However, at δ = -3° the lift coefficient decrease slightly from CL = 0.7573 to CL = 0.7518 at δ = 0°. As the canard setting angle is increases, the lift coefficient is decreasing until at δ = 6°, there is an insignificantly minute difference in the lift coefficient CL = 0.7250 at δ = 6° compared to CL = 0.7215 at δ = 8°. 0.9 0.8
Lift Coefficient, CL
0.7 0.6 0.5 CL vs δ
0.4
Poly. (CL vs δ)
0.3 0.2 0.1 0 -22
-17
-14
-11
-8
-6
-3
0
3
6
8
Canard Setting Angle, δ (°)
Figure 5.1 Lift Coefficient, CL versus Canard Setting Angle, δ
Based on the curve of lift coefficient against canard setting angle, the maximum lift coefficient would be at δ = -11° with CL, max = 0.7886. At maximum coefficient of lift, it should show that the velocity flow is fully separated from the
56
upper surface of the canard. However, referring to Figure 5.2, at δ = -11°, the velocity flow is not fully separated from the upper surface of the canard.
Figure 5.2 Mach number at δ = -11°, upper surface
Figure 5.3 Mach number at δ = -11°, bottom surface 57
Figure 5.4 Canard’s velocity vector at δ = -11° Therefore, a polynomial trend line is used to obtain the best line for the graph. Based from the trend line, it can be determine that the maximum lift coefficient where stall will occur is at δ = -3°. Figures below shows the figures of Mach number contour and velocity vectors at the canard for δ = -3° and δ = 3°.
58
Figure 5.5 Mach number contour at δ = -3°, upper surface
Figure 5.6 Mach number contour at δ = -3°,bottom surface
59
Figure 5.7 Canard’s velocity vectors at δ = -3°
60
Figure 5.8 Mach number contour at δ = 3°, upper surface
Figure 5.9 Mach number contour at δ = 3°, bottom surface
61
Figure 5.10 Canard’s velocity vectors at δ = 3° From Figure 5.7, it can be observed that there is a maximum flow separation occurred on the upper side of the canard. Therefore, it can be confirmed that the maximum lift coefficient, CL,
max
= 0.7573 which occurs at stall angle of canard
deflection, δ = -3°.
5.1.3
Coefficient of Drag, CD
The figure below shows the graph of drag coefficient, CD against canard setting angle, δ. From the graph, the value of drag coefficient, CD is fluctuating from canard setting angle, δ = -22° to δ = -8°. From canard setting angle, δ = -8° the drag coefficient increases slightly linear until it reaches canard setting angle of δ = 3°. At this canard setting angle, the stall has occurred. It can be observed that the drag coefficient curve is nearly constant till canard setting angle of δ = 6°. From this point, the drag coefficient increase slightly until canard setting angle δ = 8°. Adding a polynomial trend line shows the best line for the graph of drag coefficient, CD against canard setting angle, δ. The trend line shows a parabolic manner. The graph shows a declination of the curve from δ = -22° to δ = -5°. However, the curve starts 62
to increase from that point onwards. By referring to the trend line, the minimum drag coefficient is located near canard setting angle δ = -5°. At the minimum drag coefficient shows the minimum resistance to the body.
0.2 0.18 Drag Coefficient, CD
0.16 0.14 0.12 0.1
CD vs δ
0.08
Poly. (CD vs δ)
0.06 0.04 0.02
-25
-20
-15
0 -10 -5 0 Canard Setting Angle, δ (°)
5
10
Figure 5.11 Drag Coefficient, CD versus Canard Setting Angle, δ
63
5.1.4
Coefficient of Pitching Moment, CM
Figure below shows the graph of pitching moment coefficient, CM versus the angle of canard deflection, δ with the angle of attack 10°. The graph shows a slight increment from δ = -22° until δ = -17°. The graph then increase steeply until δ = -8° with CM = -0.1254. However, at δ = -8° the graph fluctuated until it reached δ = -5° at CM = -0.1118. The graph continues to increase until δ = 8° with CM = -0.0507. Pitching moment describe the torque in result of the rotation of body. The graph shows a steep increment from δ = -17° until δ = -8° which indicates that the canard is still producing lift as seen in Figure 5.1, the lift coefficient is increasing through that canard setting angle. However, due to the canard is approaching to its maximum lift coefficient, the pitching moment increase slightly.
0 -25
-20
-15
-10
-5
0
5
10
Pitching Moment Coefficient, CM
-0.05
-0.1
-0.15 CM vs δ -0.2
-0.25
-0.3
-0.35 Canard Setting Angle, δ (°)
Figure 5.12 Pitching Moment Coefficient, CM versus Canard Setting Angle, δ
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5.1.5
Pressure Distribution From the pressure distribution, when there is a difference in pressure at upper
and lower surface of the body, the body will experience lift.
Figure 5.13 Pressure contours at δ = -11° for upper (left) and lower (right) surfaces
Figure 5.14 Pressure contours at δ = -5° for upper (left) and lower (right) surfaces
Figure 5.15 Pressure contours at δ = -3° for upper (left) and lower (right) surfaces 65
Figure 5.16 Pressure contours at δ = 3° for upper (left) and lower (right) surfaces
Figure 5.14 shows the pressure contours at δ = -5°. As mentioned previously, the minimum drag coefficient is at δ = -5°. It can be observed that at δ = -5° the pressure at the leading edge of wing is less compared to other canard setting angle. When the pressure is less, the resistance to the wind is also decrease. Since the resistance is less, the drag is at its minimum. Figures above show that there is a pressure difference at the upper and lower surfaces. The pressure at the lower surface is higher than the pressure at the upper surface. As a result, the lift force is produced due to this difference in pressure distribution.
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CHAPTER VI
6.0
CONCLUSION AND RECOMMENDATION
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6.1
Conclusion The BWB Baseline-II E5-8 have a maximum lift coefficient, CL, max = 0.7573
at canard setting angle δ = -3°. At this point, the flow separation occurs which result in stall. From the result obtained, the minimum drag coefficient is located at canard setting angle δ = -5° with CD = 0.1430. 6.2
Recommendation There are some improvements that can be done for the future work. 1) Improve mesh quality by using a smaller mesh size to obtain the finest mesh 2) Increase the initial mesh parameter to increase the number of mesh in the boundary. 3) Upgrade the existing computer in order for it to be able to run simulation of a body with more number of cells and smaller mesh size.
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7.0
REFERENCES
1.
Robert F. Stengel, “Aircraft Flight Dynamics”, 2008.
2.
John P. Fielding, “Introduction to Aircraft Design”, 2008.
3.
John D. Anderson, “Introduction to Flight”, 2008.
4.
Thomas C. Corke, “Design of Aircraft”. Upper Saddle River, New Jersey: Pearson/Prentice Hall, 2003.
5.
Zurriati M. Ali, Wahyu Kuntjoro, Wirachman Wisnoe, Rizal E. M Nasir. “The Effect of Canard on Aerodynamics of Blended Wing Body”, Applied Mechanics and Materials, Trans Tech Publications, Switzerland.
6.
http://www.aerospaceweb.org/question/dynamics/q0045.shtml, September 23, 2001.
7.
Yunus A.Cengel, John M. Cimbala, “Fluid Mechanics Fundamentals and Applications”, Singapore, Mc-Graw Hill, 2006.
8.
Canards, Evan Neblett, Mike Metheny, Leifur Thor Leifsson, AOE 4124 Configuration Aerodynamics Virginia Tech 17. March 2003.
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9.
M.R. Soltani, F. Askari, A.R. Davari and A. Nayebzadeh. “Effects of Canard Position on Wing Surface Pressure Transaction” Mechanical Engineering Vol. 17, No. 2, pp. 136-145, Sharif University of Technology, April 2010.
10.
Thomas C. Corke, “Design of Aircraft”. Upper Saddle River, New Jersey: Pearson/Prentice Hall, 2003.
11.
The Blended Wing Body Aircraft Leifur T. Leifsson and William H. Mason Virginia Polytechnic Institute and State University Blacksburg, VA, USA.
12.
N. Qin, A. Vavalle, A Le Moigne, M. Laban, K.Hackett, P. Weinerfelt. Aerodynamics Studies for Blended Wing Body Aircraft. 9th AIAA/ISSMO Symposium on Multidisciplinary Analysis and optimization, 4 – 6 September (2002), Atlanta, Georgia.
13.
S. Siouris, N. Qin. Study of the Effects of Wing Sweep on the Aerodynamic Performance of a Blended Wing Body. (2006) Aerodynamics and Thermofluids Group, Department of Mechanical Engineering, University of Sheffield, UK.
14.
Wirachman Wisnoe, Wahyu Kuntjoro, Firdaus Mohamad, Rizal Effendy Mohd Nasir, Nor F Reduan, Zurriati Ali, "Experimental Results Analysis for UiTM BWB Baseline-I and Baseline-II UAV Running at 0.1 Mach number", International Journal of Mechanics, Issue 2, Volume 4, 2010, ISSN: 19984448, pp. 23-32.
15.
John P. Fielding, “Introduction to Aircraft Design”, 2008.
16.
Zurriati M. Ali, Wahyu Kuntjoro, Wirachman Wisnoe, Rizal Efendy M. Nasir, Firdaus Mohamad, Nor F. Reduan, “The Aerodynamics Performance of Blended Wing Body Baseline-II E2”, The 2011 International Conference on Fluid Dynamics and Thermodynamics Technologies (FDTT 2011), Bali, Indonesia, April 1-3, 2011, ISBN: 978-1-4244-9831-4.
17.
http://science.howstuffworks.com/transport/flight/modern/airplanes5.htm
18.
http://science.howstuffworks.com/transport/flight/modern/airplanes1.htm 70
19.
Zurriati M. Ali, Wahyu Kuntjoro, Wirachman Wisnoe, Rizal Efendy M. Nasir, Matzaini K., “The Aerodynamic Study of Low Aspect Ratio Canard on BWB-Baseline II E2”, The 2010 International Conference on Advances in Mechanical Engineering (ICAME 2010), Faculty of Mechanical Engineering, UiTM.
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APPENDICES APPENDIX A – CAD Drawing of BWB Baseline II E5-8
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APPENDIX B – Velocity Vectors Flow Visualization
Velocity Vectors on BWB Baseline II E5-8 Canard Setting Angle, δ = -8°
Canard Setting Angle, δ = -5°
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Canard Setting Angle, δ = -3°
Canard Setting Angle, δ = 0°
Canard Setting Angle, δ = 3°
74
APPENDIX B1 – Velocity Vectors Flow Visualization
Wing’s Velocity Vectors Canard Setting Angle, δ = -8°
Canard Setting Angle, δ = -5°
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Canard Setting Angle, δ = -3°
Canard Setting Angle, δ = 0°
Canard Setting Angle, δ = 3°
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