Design and Analysis of Morphing Wing for Unmanned Aerial Vehicles

87 Pages·2010·9.93 MB·English

Design and Analysis of Morphing Wing
for Unmanned Aerial Vehicles
by
Vlad Paul Galantai
A thesis submitted in conformity with the requirements
for the degree of Masters of Applied Science
Department of Mechanical and Industrial Engineering
University of Toronto
Copyright by Vlad Paul Galantai 2010
Design and Analysis of Morphing Wing
for Unmanned Aerial Vehicles
Vlad Paul Galantai
Masters of Applied Science
Department of Mechanical and Industrial Engineering
University of Toronto
2010
Abstract
This study is concerned with the design and development of a novel wing for UAVs that
morphs seamlessly without the use of complex hydraulics, servo motors and controllers. The
selected novel design is characterized by a high degree of (cid:29)ight adaptability and improved
performance with a limited added weight. These characteristics were attained through the
use of shape memory actuators in an antagonistic fashion. Unlike compliant actuators, the
antagonistic setup requires the thermal energy to deform the wing but not to maintain its
deformedshape. Structuralanalysisbaseduponsafetyfactorsspeci(cid:28)edbyFAR23standards
and aerodynamic analysis using FLUENT were conducted on the novel design to validate
its suitability as a viable wing for UAVs. In addition, thermal conditioning of the shape
memory actuators was conducted using a specially designed programmable controller. This
thesisdoesnotconcernitselfwiththedesignofaskinthataccommodatestheshapechanges.
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Acknowledgments
The author is grateful for the (cid:28)nancial support provided by Defence Science Organization
National Laboratories of Singapore, under contract number DSOCO07212. The author also
wishes to thank Professor Meguid for the kind supervision, the careful guidance and all the
help he provided in the past two years, while working on this project. Finally, he wishes to
thank Dr. So(cid:29)a for all the support and for a very pleasant collaboration.
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To My Family
For All Their Support
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Contents
1 Introduction and Justi(cid:28)cation 1
1.1 Unmanned Aerial Vehicles . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Morphing and Shape Adaptation in Aircraft . . . . . . . . . . . . . . . . . . 3
1.3 Morphing using Shape Memory Alloys . . . . . . . . . . . . . . . . . . . . . 4
1.4 Objectives of Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.5 Method of Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2 Literature Review 8
2.1 Unmanned Aerial Vehicles - Historical Overview . . . . . . . . . . . . . . . . 8
2.2 A Brief History of Morphing Wings . . . . . . . . . . . . . . . . . . . . . . . 11
2.3 Existing Adaptive Wings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.4 Current State of the Art of Morphing . . . . . . . . . . . . . . . . . . . . . . 13
2.5 Wing Planform Morphing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.5.1 Wing Span Resizing . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.5.2 Chord Length Change . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.5.3 Sweep Angle Variation . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.6 Out-of-plane Transformations . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.6.1 Airfoil Camber Change . . . . . . . . . . . . . . . . . . . . . . . . . . 18
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2.6.2 Lateral Wing Bending . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.6.3 Wing Twisting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.6.4 Airfoil Pro(cid:28)le Adjustment . . . . . . . . . . . . . . . . . . . . . . . . 23
3 Conceptual Design of Morphing Wings for Unmanned Aerial Vehicles 24
3.1 Design Speci(cid:28)cation of UAV . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.2 Preliminary Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.2.1 Adaptive Airfoil Concept . . . . . . . . . . . . . . . . . . . . . . . . . 26
3.2.2 Airfoil Tracer Concept . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.2.3 Variable Morphing Wing Concept . . . . . . . . . . . . . . . . . . . . 30
3.2.4 Adaptive Octahedron Concept . . . . . . . . . . . . . . . . . . . . . . 32
3.3 The Selected Design: The Adaptive Octahedron Concept . . . . . . . . . . . 37
3.4 Development of Prototype . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
3.5 Conditioning of Shape Memory Alloys . . . . . . . . . . . . . . . . . . . . . 39
4 Aerodynamic and Load Analysis of Morphing Wing 41
4.1 CFD Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
4.1.1 Discretization of Morphed Wing . . . . . . . . . . . . . . . . . . . . . 41
4.1.2 Details of Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
4.2 Analysis of Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
4.3 Analytical Veri(cid:28)cation of Results . . . . . . . . . . . . . . . . . . . . . . . . 50
4.4 Performance Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
4.5 Load Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
5 Conclusions and Future Work 61
5.1 Statement of the Problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
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5.2 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
5.3 Thesis Contributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
5.4 Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Bibliography 64
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List of Figures
1.1 AAI Shadow 200 (After [1]) . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Comparison of mission pro(cid:28)les for a generic commercial airliner vs. a generic
surveillance UAV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 UAV funding pro(cid:28)le (After [2]) . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.4 Comparison of Manned vs. Unmanned Funding (After [2]) . . . . . . . . . . 3
1.5 Compliant vs. Antagonistic implementation of SMAs . . . . . . . . . . . . . 5
1.6 Detailed Design Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1 Diagram showing the change in e(cid:27)ective airfoil thickness-to-chord length ratio 12
2.2 Classi(cid:28)cation for shape morphing of a wing . . . . . . . . . . . . . . . . . . . 14
2.3 The in(cid:29)atable telescopic spar concept . . . . . . . . . . . . . . . . . . . . . . 16
2.4 Reed’s concept of interpenetrating partial ribs (After [3]) . . . . . . . . . . . 17
2.5 Span-wise camber variation of Fowler (cid:29)aps (After [4, 5]) . . . . . . . . . . . 18
2.6 The antagonistic (cid:29)exural unit cell (After [6]) . . . . . . . . . . . . . . . . . . 20
2.7 Lockheed Martin morphing UAV (After [7]) . . . . . . . . . . . . . . . . . . 21
2.8 Morphing wing using the eccentuator concept (After [8]) . . . . . . . . . . . 22
3.1 Detailed Morphing Wing Design Methodology . . . . . . . . . . . . . . . . . 25
3.2 Adaptive Airfoil Concept: Span-wise section of the wing . . . . . . . . . . . 27
3.3 Airfoil change as a result of chord length variation . . . . . . . . . . . . . . . 27
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3.4 Top view - Four planform con(cid:28)gurations . . . . . . . . . . . . . . . . . . . . 28
3.5 Sectionshowingthe(cid:29)exiblebeamde(cid:29)ectedbythe4actuators, thecorrugated
material and (cid:29)exible skin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3.6 Sample wing con(cid:28)gurations . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
3.7 Octahedral unit cells forming a spar, coupled to ribs via ball-joints . . . . . . 33
3.8 Top view showing the two spars. Left - straight wing; Right - backward
curved wing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
3.9 Straight wing in unmorphed and morphed states . . . . . . . . . . . . . . . . 35
3.10 Three spar structure used for the airfoil pro(cid:28)le variation along the span-wise
direction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
3.11 Prototype of an AOC spar . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
3.12 Prototype showing the (cid:29)exibility of the unit cells . . . . . . . . . . . . . . . 38
3.13 Shape memory alloy degradation (After [9]) . . . . . . . . . . . . . . . . . . 39
3.14 Automated antagonistic setup for SMA conditioning . . . . . . . . . . . . . . 40
4.1 Sample structured mesh for curved wing. Units of airfoil chord length (c) . . 43
4.2 Straight wing in-plane morphing . . . . . . . . . . . . . . . . . . . . . . . . . 46
4.3 Drag and lift coe(cid:30)cients for in-plane morphing of straight wing . . . . . . . 46
4.4 Span-wise components of (cid:29)ow. Note: the curved wing experiences a stronger
span-wise component which develops closer to the root of the wing. . . . . . 47
4.5 Swept wing in-plane morphing . . . . . . . . . . . . . . . . . . . . . . . . . . 47
4.6 Drag and lift coe(cid:30)cients for swept, morphed wing . . . . . . . . . . . . . . . 48
4.7 Straight wing, partial in-plane morphing . . . . . . . . . . . . . . . . . . . . 48
4.8 Drag and lift coe(cid:30)cients for straight, partially morphed wing . . . . . . . . . 48
4.9 Drag and lift coe(cid:30)cients for wing bending . . . . . . . . . . . . . . . . . . . 49
4.10 Drag and lift coe(cid:30)cients for wing twisting . . . . . . . . . . . . . . . . . . . 50
4.11 Power requirement for steady level (cid:29)ight for straight, morphed wing . . . . . 53
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4.12 Aerodynamic performance of baseline straight wing, and of morphed wings . 54
4.13 Elliptical lift distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
4.14 Elliptical lift distributions for the three in-plane morphed cases . . . . . . . . 56
4.15 Span-wise shear force distribution . . . . . . . . . . . . . . . . . . . . . . . . 57
4.16 Bending moment about the roll axis . . . . . . . . . . . . . . . . . . . . . . . 57
4.17 Wing twisting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
4.18 Twisting moment as a result of the wing curvature . . . . . . . . . . . . . . . 58
4.19 Shear force on spars as a result of twisting . . . . . . . . . . . . . . . . . . . 59
4.20 Bending moment about the roll axis as a result of twisting . . . . . . . . . . 59
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