Flapping Wing Design for a Dragonfly-Like Micro Air Vehicle Daniel Prosser
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Rochester Institute of Technology RIT Scholar Works Theses Thesis/Dissertation Collections 7-1-2011 Flapping wing design for a dragonfly-like micro air vehicle Daniel Prosser Follow this and additional works at: http://scholarworks.rit.edu/theses Recommended Citation Prosser, Daniel, "Flapping wing design for a dragonfly-like micro air vehicle" (2011). Thesis. Rochester Institute of Technology. Accessed from This Thesis is brought to you for free and open access by the Thesis/Dissertation Collections at RIT Scholar Works. It has been accepted for inclusion in Theses by an authorized administrator of RIT Scholar Works. For more information, please contact [email protected]. Flapping Wing Design for a Dragonfly-Like Micro Air Vehicle by Daniel T. Prosser A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science in Mechanical Engineering Advised by Dr. Agamemnon Crassidis, Assistant Professor, Mechanical Engineering Department of Mechanical Engineering Kate Gleason College of Engineering Rochester Institute of Technology Rochester, New York July, 2011 Approved by: Dr. Agamemnon Crassidis, Associate Professor Thesis Advisor, Department of Mechanical Engineering Dr. Amitabha Ghosh, Professor Committee Member, Department of Mechani- cal Engineering Dr. Jason Kolodziej, Assistant Professor Committee Member, Department of Mechanical Engineering Dr. Edward Hensel, Professor Department Representative, Department of Me- chanical Engineering Thesis Release Permission Form Rochester Institute of Technology Kate Gleason College of Engineering Title: Flapping Wing Design for a Dragonfly-Like Micro Air Vehicle I, Daniel T. Prosser, hereby grant permission to the Wallace Memorial Library to reproduce my thesis in whole or part. Daniel T. Prosser Date ©Copyright 2011 by Daniel T. Prosser All Rights Reserved i Acknowledgments I would like to thank my advisor, Dr. Crassidis, for his help in guiding me during my studies and in allowing me to become involved in this interesting research, for the Air Force in providing the contractual funding under project #FA9550-10-C- 0036, and for the assistance of my peers and colleagues also working on this project at Impact Technologies, LLC and Georgia Institute of Technology. I am also greatly thankful for the thoughts, prayers, and motivation given me by my parents, family, friends, and girlfriend. Above all, I thank God for blessing me with the intelligence and determination to finish this task; may all be done for his glory. ii Abstract In this thesis, the aerodynamics of the Quad-Wing Vehicle, a Micro Air Vehi- cle designed to hover with four flapping wings in a dragonfly-like configuration, is investigated using Computational Fluid Dynamics (CFD), potential flows analysis, and experimental testing. The CFD analysis investigates the kinematics-parameters design space and identifies values of kinematics parameters that maximize the ver- tical force production in hovering mode while minimizing the aerodynamic power requirement. It also investigates other important considerations, such as the effect of scaling, multi-wing interactions, and comparison with other flapping configura- tions. In the potential flows analysis, an unsteady 2D panel code is developed and compared with CFD for a broad range of hovering-flight simulations. The results show that, with further development, panel codes may be useful to designers of hovering flapping MAVs because of their time-saving potential compared to CFD. The experimental testing focuses on isolating the aerodynamic forces from other measured forces on a benchtop flapping device, and the findings of the experimen- tal study will be useful for later researchers using experimental methods to study flapping MAV aerodynamics. iii Contents Acknowledgments ii Abstract iii List of Figures vii List of Tables x Nomenclature xi 1 Introduction 1 1.1 Micro Air Vehicles . .2 1.1.1 The State of the Art . .3 1.2 The Quad-Wing Vehicle (QV) . .6 1.2.1 Actuation and Control . .7 1.2.2 Energy Saving Design . 10 1.2.3 Required aerodynamics research . 11 1.3 Design Tools . 12 1.3.1 Computational Fluid Dynamics . 13 1.3.2 Other computational and analytical methods . 14 1.3.3 Experimental methods . 14 2 Literature Review 16 2.1 Analytical Work . 16 2.2 Computational Work . 18 2.3 Experimental Work . 23 2.4 Statement of Work & Literature Gaps . 26 3 Computational Fluid Dynamics Analysis 29 3.1 FLUENT Solver . 30 3.1.1 Dynamic Meshing . 32 3.2 Grid Independence and Model Validation . 33 3.3 Single-Wing Parameter Sweeps . 37 3.3.1 Computational Model and Methods . 40 iv 3.3.2 Results . 45 3.4 Multi-Wing Modeling . 61 3.5 Discussion . 65 4 Potential Flows Analysis 68 4.1 Theory and Panel Code Development . 69 4.2 Panel Code and CFD Solver Validation . 79 4.3 Non-Dimensional Parameters . 81 4.3.1 Hovering Kinematics . 82 4.3.2 Π Groups . 82 4.4 ULVPC vs. CFD for Hovering Flight . 84 4.4.1 Kinematics Equations . 84 4.4.2 CFD Procedures . 86 4.4.3 Comparison of Force Coefficients and Flow Fields . 87 4.5 Discussion of Results . 95 5 Experimental Methods 97 5.1 Hardware and Test Setup . 97 5.1.1 Load Cell Selection . 98 5.1.2 Design of the mounting system . 99 5.2 Isolating Aerodynamic Forces . 100 5.2.1 Vacuum Chamber Method . 102 5.2.2 Analytical Method . 103 5.3 Results of Experimental Tests . 109 5.3.1 Recommendations for Experimental Testing . 114 6 Conclusions, Recommendations, and Future Work 117 6.1 CFD Analysis . 117 6.2 Potential Flows Analysis . 119 6.3 Experimental Analysis . 120 Bibliography 123 A Data used to create surface plots in Chapter 3 129 B Unsteady Linear Vortex Panel Code (ULVPC) for MATLAB 130 B.1 ULVPC main function . 130 B.2 Second-level functions . 135 B.2.1 Initial calculations . 135 B.2.2 Position, orientation, and velocity update . 138 B.2.3 Calculation of A, B, and C matrices . 141 B.2.4 Computation of velocities, pressures, forces, moments . 144 B.2.5 Computation of wake roll-up . 148 v B.3 Third-level functions . 150 B.3.1 Computation of vortex-panel influences . 150 B.3.2 Computation of discrete-vortex influences . 151 B.3.3 Quadrant computation for tan−1 ............... 152 B.4 Example test case: accelerating airfoil . 152 B.4.1 Kinematics function . 152 B.4.2 Workspace inputs . 152 B.4.3 Creating a movie of the simulation . 155 vi List of Figures 1.1 Black Widow MAV . .4 1.2 Delfly MAVs . .4 1.3 Hybrid flapping-fixed wing MAV . .5 1.4 Ornithopter by Petter Muren . .5 1.5 Nano Hummingbird . .5 1.6 Design configuration trade study . .6 1.7 6DOF control achieved by varying individual actuator power . .7 1.8 FiFVA actuation system . .8 1.9 QV layout concept sketch . .9 1.10 Wing motion illustration side view . .9 1.11 QV passive feathering mechanism . 10 1.12 Four-bar actuation system . 11 2.1 Ansari’s method compared with experimental results . 18 2.2 Dronefly wing mesh . 19 2.3 Leading-edge vortex . 20 2.4 Flapping in ground effect . 22 2.5 von Kármán street . 23 2.6 Leading-edge vortex visualization . 25 3.1 Methods used by Ho, et al. 33 3.2 Results of grid-independence study . 35 3.3 CFD validation study by Ho, et al. 36 3.4 FLUENT validation results . 36 3.5 Derivation of aerodynamic power requirement . 37 3.6 QV wing rotations . 39 3.7 Mesh on and around the wing . 41 3.8 CFD domain used for single-wing simulations . 42 3.9 Typical iteration-history of residuals . 45 3.10 Usable hovering force and aerodynamic power requirement . 46 3.11 Power requirement with Fh isocurves . 47 3.12 Fh isocurves side view . 48 3.13 Stroke plane inclination angle . 49 3.14 Forces and power requirement for the initial best design . 49 3.15 Dependence of Fh and P on θmax ................... 50 vii 3.16 Force and power traces for different feathering amplitudes . 51 3.17 Effect of feathering amplitude at other design points . 52 3.18 Effect of wing scale on forces and power requirement . 54 3.19 Pressure contours on the top surface of the wing . 55 3.20 Vortical structures on wing’s top surface . 56 3.21 Velocity vectors during the downstroke . 57 3.22 Wing motion illustration - horizontal stroke plane . 58 3.23 Forces and power for vertical and horizontal stroke planes . 58 3.24 Leading-edge vortex for horizontal stroke plane . 60 3.25 Leading-edge vortex: vectors in CFD and illustration . 60 3.26 Computational model of the forewing and hindwing . 62 3.27 Usable hovering force for 2-wing simulations . 63 3.28 Aerodynamic power requirement for 2-wing simulations . 64 4.1 Illustration of vortex panels with linear-varying strength . 70 4.2 Numerical representation of the airfoil and its wake . 70 4.3 Definition of kinematics . 71 4.4 Geometric definitions for solution of equations . 72 4.5 ULVPC algorithm flowchart . 78 4.6 Illustration of kinematics for the validation study . 79 4.7 Comparison of vertical force . 80 4.8 Comparison of horizontal force . 80 4.9 Illustration of wake roll-up . 81 4.10 Motion illustrations . 83 4.11 Rotational motions used for comparisons . 85 4.12 CFD grid used for comparisons . 86 4.13 Hybrid grid and unstructured grid after deformation . 87 4.14 Cx versus t/T, first motion . 89 4.15 Cz versus t/T, first motion . 90 4.16 Vortex shedding during stroke reversal . 90 4.17 ULVPC vector fields before stroke reversal . 91 4.18 Cx versus t/T, second.