Phase II Final Report - NASA's Institute for Advanced Concepts

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Planetary Exploration Using Biomimetics An Entomopter for Flight on Mars Figure 3-69: Pressure Contours, α = 45.79 o , Reynolds Number = 5,100, Time = 3.6248 s Figure 3-70: Pressure Contours, α = 45.79 o , Reynolds Number = 5,100, Time = 3.6548 s 90 Phase II Final Report
Chapter 3.0 Vehicle Design 3.3 Wing Aerodynamics Figure 3-71: Pressure Contours, α = 45.79 o , Reynolds Number = 5,100, Time = 3.6848 s 3.3.1.4.1 Low Reynolds Number, High-α Results A new cambered, thin wing modeled after the North American cicada wing was used in this series of simulations. Chord Reynolds number was varied in the range 510-5,100. A high angle of attack value was used to characterize the formation and evolution of the LEV. These timeaccurate simulations were done using a very fine mesh and small integration time step. Both the mesh size and the time step were varied and the corresponding simulation results compared to ensure the results can be treated as independent of mesh size and time step. Figures 3-72 and 3-73 show, respectively, the lift and drag coefficient variations for U = 1.4 m/s (Reynolds number = 510, Case A) and α = 34.8 o . The corresponding plots for U = 14 m/s (Reynolds number = 5,100, Case D) are shown in Figures 3-74 and 3-75. These four plots reveal several interesting characteristics not emphasized in previous work by other investigators of low Reynolds number, high angle of attack flow. Both cases show that there are distinct frequencies associated with each, and both the lift and drag variations have fairly large amplitudes. The salient features are summarized in Table 3-7. These results indicate that the flow is dominated by the formation and shedding of the LEV. The LEV forms at the leading edge, stays attached to the top surface and grows as it convects downstream. During this phase, the airfoil has a high C L value, and then it drops as the vortex detaches from the surface, leading to the low C L phase of the cycle. The c d variation has a phase difference of approximately 180 o from the C L variation. From the summary results given in Table 3-7, several useful design guidelines can be drawn. For example, for Case D (Reynolds number = 5,100) the dominant frequency is f ~ 7.23 Hz. To investigate the relationship to the well known Karman vortex shedding from bluff bodies, the Strouhal number, defined as 91
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Planetary Exploration Using Biomime
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Table of Contents Table of Contents
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List of Tables List of Tables Table
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List of Figures List of Figures Fig
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List of Figures Figure 3-54: Pressu
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List of Figures Figure 3-138: Stere
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List of Figures Figure 4-24: Averag
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List of Contributors List of Contri
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Executive Summary Executive Summary
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Chapter 1.0 Introduction Chapter 1.
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Chapter 1.0 Introduction Figure 1-2
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Chapter 1.0 Introduction 1.1 Histor
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Chapter 1.0 Introduction 1.2 Origin
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Chapter 1.0 Introduction 1.3 Missio
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1.3.3.1 Surface Imaging The Entomop
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Chapter 2.0 Entomopter Configuratio
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Chapter 3.0 Vehicle Design 3.3 Wing
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Chapter 3.0 Vehicle Design 3.5 Fuel
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Chapter 4.0 Entomopter Flight Opera
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Chapter 5.0 Potential Payload Funct
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Chapter 6.0 Media Exposure 6.1 Intr
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Chapter 6.0 Media Exposure 6.3 Onli
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Chapter 6.0 Media Exposure 6.6 Spec
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Chapter 7.0 Conclusion Chapter 7.0
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Appendix A: Mars Atmosphere Data JP
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Appendix A: Mars Atmosphere Data Ge
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Appendix A: Mars Atmosphere Data Ge
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Appendix A: Mars Atmosphere Data Ma
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Appendix B: Sizing Results Appendix
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Appendix B: Sizing Results 30 Wing
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Appendix B: Sizing Results 16 Wing
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Appendix B: Sizing Results Length 0
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Appendix B: Sizing Results Lenght 0
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Appendix C: List of References Appe
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Appendix C: List of References 41.
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Phase II Final Report - NASA's Institute for Advanced Concepts

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