Aerodynamics and Design for Ultra-Low Reynolds Number Flight

More documents

Recommendations

Info

Chapter 7 168 Figure of Merit 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 Suggested Upper Performance Limit from Basic Rotor Theory 0.0 34000 38000 42000 46000 50000 54000 RPM FIGURE 7.7 Figure of merit for the four-blade 2.5cm diameter rotor. The potential benefits of improved performance on the power required for hover can be demonstrated by utilizing Eqn.7.8. Improving the measured performance from M=0.39 to M=0.6 at a vehicle mass of 17.1g would represent a decrease in the thrust specific power from 15.1W/N to 9.8W/N. Once translated through the system efficiency of 15%, this represents a 35% drop, or almost six Watts, in the system power required. It is clear that improving upon the measured aerodynamic performance of these rotors would partially mitigate the system efficiency issues and move further toward achieving powered flight at the smallest physical scales. Rapid Analysis Method Aluminum Rotor, Experiment OVERFLOW-D
Chapter 8 Conclusions and Recommendations Achieving powered flight at ultra-low Reynolds numbers and true micro-aircraft scales requires a greater understanding of aerodynamics in a flow regime that, until now, has only been minimally explored. The goals of this research have been to broadly explore the aerodynamics of this environment and then to use the insight gained to analyze, design, manufacture, and test micro-rotors of an unprecedented small physical scale. In the culmination of this effort, micro-rotorcraft have been proposed and developed that represent both the current state-of-the art and what lies just beyond it. 8.1 Summary of Results and Contributions in the Area of Two-Dimensional Aerodynamics Airfoils in this regime face unique operating conditions and the two-dimensional computational study represents the first comprehensive and quantitative exploration of the airfoil design space at ultra-low Reynolds numbers. Under these conditions, the flow is dominated by viscous effects and the growth of thick boundary layers causes significant modifications to the effective geometry of the section. This effective loss of camber is exacerbated by the fact that flow separation occurs at low angles of attack. However, the onset of separation does not have to have the same catastrophic 169
Page 1 and 2:
AERODYNAMICS AND DESIGN FOR ULTRA-L
Page 3:
I certify that I have read this dis
Page 7 and 8:
Abstract Growing interest in micro-
Page 9 and 10:
Nomenclature A Rotor disk area B Nu
Page 11 and 12:
τ Shear stress ω, Ω Rotor angul
Page 13 and 14:
Contents Acknowledgments...........
Page 15 and 16:
Chapter 5..........................
Page 17 and 18:
List of Tables 3.1 Effect of Airfoi
Page 19 and 20:
List of Figures 2.1 Comparison of I
Page 21 and 22:
5.6 Small test fixture in the large
Page 23 and 24:
6.38 Predicted spanwise thrust dist
Page 25 and 26:
Chapter 1 Introduction 1.1 Looking
Page 27 and 28:
Chapter 1 wind-tunnel facilities an
Page 29 and 30:
1.3 Summary of Contributions Chapte
Page 31 and 32:
Chapter 2 Two-Dimensional Computati
Page 33 and 34:
Chapter 2 The artificial compressib
Page 35 and 36:
Chapter 2 The control volume method
Page 37 and 38:
2.2.4 Comparison with Experiment Th
Page 39 and 40:
Chapter 2 to diverge if significant
Page 41 and 42:
2.4 Flow Field Assumptions The INS2
Page 43 and 44:
Chapter 2 The results of these time
Page 45 and 46:
Chapter 3 Analysis and Design of Ai
Page 47 and 48:
Chapter 3 adverse gradient in the p
Page 49 and 50:
The canonical pressure coefficient
Page 51 and 52:
Chapter 3 reaches α=5.0 and a lift
Page 53 and 54:
��
Page 55 and 56:
Cl 0.50 0.40 0.30 0.20 0.10 0.00 -0
Page 57 and 58:
Re=6000 result due to Reynolds numb
Page 59 and 60:
FIGURE 3.10 NACA 0002 and NACA 0008
Page 61 and 62:
C l C l 0.8 0.7 0.6 0.5 0.4 0.3 0.2
Page 63 and 64:
Chapter 3 The maximum L/D for all n
Page 65 and 66:
3.5 Effect of Leading Edge Shape an
Page 67 and 68:
C l 0.60 0.50 0.40 0.30 0.20 0.10 0
Page 69 and 70:
Chapter 3 prominent droop near the
Page 71 and 72:
Chapter 3 Small improvements in lif
Page 73 and 74:
Chapter 4 Hybrid Method for Rotor D
Page 75 and 76:
Q/r D L Chapter 4 FIGURE 4.1 Typica
Page 77 and 78:
4.2.3 Elimination of Trigonometric
Page 79 and 80:
Chapter 4 applications of interest
Page 81 and 82:
4.2.7 The Distinction Between the A
Page 83 and 84:
Chapter 4 Two input parameters dete
Page 85 and 86:
Chapter 4 simplification, particula
Page 87 and 88:
4.3.3 Conservation of Angular Momen
Page 89 and 90:
Chapter 4 moves downstream is less
Page 91 and 92:
Chapter 4 of the pitch angle at the
Page 93 and 94:
FIGURE 4.6 Converged wake streamlin
Page 95 and 96:
Chapter 4 idealized models. The met
Page 97 and 98:
��
Page 99 and 100:
Chapter 5 Overview of Experimental
Page 101 and 102:
1. Substrate Preparation 2. Polymer
Page 103 and 104:
Chapter 5 surface finish and aids i
Page 105 and 106:
FIGURE 5.5 Small test fixture in th
Page 107 and 108:
Chapter 5 The direct influence of t
Page 109 and 110:
FIGURE 5.9 Large test fixture in th
Page 111 and 112:
5.4.1 Motor Power Supply All tests
Page 113 and 114:
Chapter 5 or roughly (+/-) 25% of t
Page 115 and 116:
Chapter 5 newly forming blade tip v
Page 117 and 118:
FIGURE 5.14 Near-body grid geometry
Page 119 and 120:
Chapter 6 Design Examples and Compa
Page 121 and 122:
Chapter 6 capable of speeds up to 1
Page 123 and 124:
FIGURE 6.2 The Astro Flight Firefly
Page 125 and 126:
t/c 0.5 0.4 0.3 0.2 0.1 0.0 FIGURE
Page 127 and 128:
c/R 0.0 0.2 0.4 0.6 0.8 1.0 r/R Cha
Page 129 and 130:
FIGURE 6.10 Carbon-fiber two-blade
Page 131 and 132:
Power Req. (W) 3.5 3.0 2.5 2.0 1.5
Page 133 and 134:
Chapter 6 TABLE 6.1 Comparison of p
Page 135 and 136:
Electro-mechanical Efficiency 0.20
Page 137 and 138:
these variations and possible solut
Page 139 and 140:
upper and lower surface corners of
Page 141 and 142: Chapter 6 The Sample-1 rotor exhibi
Page 143 and 144: The static deformations described i
Page 145 and 146: Q( r) This problem is solved as a l
Page 147 and 148: Structural Analyses Chapter 6 The m
Page 149 and 150: Aero-Structural Twist (deg.) 0.00 -
Page 151 and 152: Thrust (g) 5 4 3 2 1 0 10000 20000
Page 153 and 154: Thrust (g) 4.5 4.0 3.5 3.0 2.5 2.0
Page 155 and 156: Torque per unit span (g cm) 0.75 0.
Page 157 and 158: Thrust per unit span (g) 3.5 3.0 2.
Page 159 and 160: V total / ωr 1.0 0.9 0.8 Classical
Page 161 and 162: Torque per unit span (g cm) 0.75 0.
Page 163 and 164: Chapter 6 Recall that this rotor wa
Page 165 and 166: Incidence (deg.) 30 25 20 15 10 5 0
Page 167 and 168: Thrust (g) 9 8 7 6 5 4 3 2 38000 40
Page 169 and 170: x/R 0.4 0.2 0.0 -0.2 Chapter 6 FIGU
Page 171 and 172: Cl 0.64 0.62 0.60 0.58 0.0 0.2 0.4
Page 173 and 174: C f 0.125 0.100 0.075 0.050 0.025 0
Page 175 and 176: Chapter 7 Micro-Rotorcraft Prototyp
Page 177 and 178: This vehicle does not currently inc
Page 179 and 180: FIGURE 7.2 The 65g prototype electr
Page 181 and 182: 7.4 The 150g Prototype Chapter 7 Th
Page 183 and 184: At hover, with a mass of 153g, the
Page 185 and 186: Using the 150g prototype as an exam
Page 187 and 188: Chapter 7 Basic rotor theory has be
Page 189 and 190: most of the blade. These values are
Page 191: Chapter 7 For large scale helicopte
Page 195 and 196: the significant performance gains a
Page 197 and 198: Chapter 8 are also opportunities to
Page 199 and 200: Chapter 8 formation flight, and man
Page 201 and 202: References [1] Spedding, G.R., Liss
Page 203 and 204: [28] Lamb, Sir Horace, Hydrodynamic
show all

Aerodynamics and Design for Ultra-Low Reynolds Number Flight

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?