EFFECTS OF TURBULENCE ON FIXED WING SMALL UNMANNED AERIAL SYSTEMS By ...

306 Pages·2013·27.66 MB·English

EFFECTS OF TURBULENCE ON FIXED WING SMALL UNMANNED AERIAL
SYSTEMS
By
MICHAEL J. SYTSMA
A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA
2013
c 2013 Michael J. Sytsma
(cid:13)
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To my wife Rosalyn and my family
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ACKNOWLEDGMENTS
I would first like to thank my wife for patience and support as I have performed
countless tests and analysis through the years. She always listened to my rants with
patience and love. I would like to extend great thanks to my family for their continued
support in my educational goals. I am indebted to the multitude colleagues who have
worked in and around the Research and Engineering Education Facility, as they have
been of great help throughout the years. I want to acknowledge Dr. Ukeiley for being my
advisor and helping me through this research, as well as the rest of my committee, Drs.
Peter Ifju, Rick Lind, Forrest Masters, and David Bloomquist. A great additional thanks
to the Air Force SEEK EAGLE Office and Air Force Research Laboratory for supporting
me through this research, both in time and technical expertise. A last grateful thanks to
the Air Force Office of Scientific Research for providing funding for me to perform this
research.
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TABLE OF CONTENTS
page
ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
CHAPTER
1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
1.1 Background of Turbulence Effects on Manned Aircraft . . . . . . . . . . . 22
1.2 Turbulence on Small Unmanned Aircraft . . . . . . . . . . . . . . . . . . . 31
1.3 Research Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
1.4 Research Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
1.5 Contributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
1.6 Dissertation Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
2 EXPERIMENTAL FACILITIES AND TECHNIQUES . . . . . . . . . . . . . . . . 36
2.1 Aerodynamic Characterization Facility . . . . . . . . . . . . . . . . . . . . 36
2.2 Turbulence Grids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
2.2.1 Static Turbulence Grid . . . . . . . . . . . . . . . . . . . . . . . . . 37
2.2.2 Active Turbulence Grid . . . . . . . . . . . . . . . . . . . . . . . . . 37
2.2.3 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
2.2.4 Computer Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
2.2.5 Forcing Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
2.3 Constant Temperature Anemometry . . . . . . . . . . . . . . . . . . . . . 44
2.4 Modal Testing and Structural Deconvolution Filtering . . . . . . . . . . . . 49
2.4.1 Structural Dynamics . . . . . . . . . . . . . . . . . . . . . . . . . . 49
2.4.2 Frequency Response Function Inverse Filtering Technique . . . . . 54
2.4.3 Limitations of Deconvolution Filter . . . . . . . . . . . . . . . . . . . 59
2.5 Particle Image Velocimetry . . . . . . . . . . . . . . . . . . . . . . . . . . 60
2.5.1 LaVision System Details . . . . . . . . . . . . . . . . . . . . . . . . 60
2.5.2 Basic PIV Technique . . . . . . . . . . . . . . . . . . . . . . . . . . 61
2.5.3 Stereo PIV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
2.5.4 Sources of Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
2.5.5 Quantification of Error . . . . . . . . . . . . . . . . . . . . . . . . . 68
3 CHARACTERIZATION OF WIND TUNNEL ENVIRONMENT . . . . . . . . . . 86
3.1 Baseline Wind Tunnel Testing . . . . . . . . . . . . . . . . . . . . . . . . . 86
3.2 CTA Data Sampling and Analysis . . . . . . . . . . . . . . . . . . . . . . . 86
3.3 Sampling Error Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
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3.4 Active Turbulence Grid Single Point Statistics . . . . . . . . . . . . . . . . 93
3.5 Active Turbulence Grid Transverse Survey . . . . . . . . . . . . . . . . . . 95
3.6 Active Turbulence Grid Multiple Point Measurements . . . . . . . . . . . . 97
3.7 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
4 LOW ORDER COMPUTATIONAL MODELING . . . . . . . . . . . . . . . . . . 114
4.1 Statistical Representations of Turbulence . . . . . . . . . . . . . . . . . . 114
4.2 Finite Impulse Response Filter Turbulence Synthesis . . . . . . . . . . . . 117
4.3 Unsteady 2-D Vortex Lattice Method . . . . . . . . . . . . . . . . . . . . . 120
4.3.1 Basic Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
4.3.2 Turbulence Boundary Conditions . . . . . . . . . . . . . . . . . . . 122
4.4 2-D Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
4.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
5 EXPERIMENTAL LOAD RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . 137
5.1 Desired Reynolds Numbers and Turbulence Data . . . . . . . . . . . . . . 138
5.2 Mean Loads Uncertainty Treatments . . . . . . . . . . . . . . . . . . . . . 139
5.2.1 Typical Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
5.2.2 Modification to Standard Error Treatment . . . . . . . . . . . . . . . 141
5.3 Mean Loads in Baseline Flow . . . . . . . . . . . . . . . . . . . . . . . . . 143
5.4 Mean Loads in the Presence of Turbulence . . . . . . . . . . . . . . . . . 146
5.5 Unsteady Loads in the Presence of Turbulence . . . . . . . . . . . . . . . 149
5.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
6 EXPERIMENTAL FLOW RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . 168
6.1 Chordwise Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
6.1.1 Case A Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
6.1.2 Case B Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
6.1.3 Case C Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
6.1.4 Case D Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
6.1.5 Shear Layer Scaling Analysis and Similarity Solution . . . . . . . . 174
6.1.5.1 Order of magnitude and simplified shear equation . . . . 174
6.1.5.2 Similarity solution . . . . . . . . . . . . . . . . . . . . . . 179
6.1.5.3 Comparison of analytical solution to PIV data . . . . . . . 180
6.2 Downstream Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
6.2.1 Case A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
6.2.2 Case B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
6.2.3 Case C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
6.2.4 Case D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
6.2.5 Fitting Vortex Models to Data . . . . . . . . . . . . . . . . . . . . . 184
6.3 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
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7 SUMMARY AND FUTURE WORK . . . . . . . . . . . . . . . . . . . . . . . . . 207
7.1 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
7.2 Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
APPENDIX
A ACTIVE TURBULENCE GRID CHARACTERIZATION . . . . . . . . . . . . . . 212
B TIME VARYING LOADS IN THE PRESENCE OF TURBULENCE . . . . . . . . 244
C SIMILARITY SCALING RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . 277
REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292
BIOGRAPHICAL SKETCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306
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LIST OF TABLES
Table page
1-1 Summary of adverse turbulence effects on aircraft . . . . . . . . . . . . . . . . 22
2-1 Frequency response function models . . . . . . . . . . . . . . . . . . . . . . . 52
4-1 Spectra function forms of Dryden and Von-Karman turbulence models . . . . . 115
4-2 Transfer function forms of Dryden and Von-Karman turbulence models . . . . 118
5-1 Model Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
5-2 ATG turbulence statistics at speeds to yield Reynolds numbers at X = 12.5 . . 138
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5-3 Standard deviations of load in various situations . . . . . . . . . . . . . . . . . 140
6-1 Chosen α for different . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
A
6-2 Table of relevant tip vortex properties . . . . . . . . . . . . . . . . . . . . . . . . 186
A-1 ATG turbulence statistics with wind tunnel throttle at 14.5% and at X = 5 . . . 212
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A-2 ATG turbulence statistics with wind tunnel throttle at 14.5% and at X = 10 . . . 213
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A-3 ATG turbulence statistics with wind tunnel throttle at 14.5% and at X = 12.5 . 214
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A-4 ATG turbulence statistics with wind tunnel throttle at 14.5% and at X = 15 . . 215
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A-5 ATG turbulence statistics with wind tunnel throttle at 14.5% and at X = 20 . . 216
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A-6 ATG turbulence statistics with wind tunnel throttle at 28.5% and at X = 5 . . . 217
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A-7 ATG turbulence statistics with wind tunnel throttle at 28.5% and at X = 10 . . 218
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A-8 ATG turbulence statistics with wind tunnel throttle at 28.5% and at X = 12.5 . 219
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A-9 ATG turbulence statistics with wind tunnel throttle at 28.5% and at X = 15 . . 220
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A-10ATG turbulence statistics with wind tunnel throttle at 28.5% and at X = 20 . . 221
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A-11ATG turbulence statistics with wind tunnel throttle at 43.5% and at X = 5 . . . 222
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A-12ATG turbulence statistics with wind tunnel throttle at 43.5% and at X = 10 . . 223
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A-13ATG turbulence statistics with wind tunnel throttle at 43.5% and at X = 12.5 . 224
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A-14ATG turbulence statistics with wind tunnel throttle at 43.5% and at X = 15 . . 225
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A-15ATG turbulence statistics with wind tunnel throttle at 43.5% and at X = 20 . . 226
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A-16ATG turbulence statistics with wind tunnel throttle at 58% and at X = 5 . . . . 227
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A-17ATG turbulence statistics with wind tunnel throttle at 58% and at X = 10 . . . 228
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A-18ATG turbulence statistics with wind tunnel throttle at 58% and at X = 12.5 . . 229
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A-19ATG turbulence statistics with wind tunnel throttle at 58% and at X = 15 . . . 230
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A-20ATG turbulence statistics with wind tunnel throttle at 58% and at X = 20 . . . 231
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LIST OF FIGURES
Figure page
2-1 Diagram of Aerodynamic Characterization Facility at UF REEF . . . . . . . . . 70
2-2 ATG after a run with random angular displacements . . . . . . . . . . . . . . . 70
2-3 Diagram of ATG Control Connections . . . . . . . . . . . . . . . . . . . . . . . 71
2-4 X-wire probe in tunnel on rotary stage . . . . . . . . . . . . . . . . . . . . . . . 71
2-5 A sample normal calibration plot . . . . . . . . . . . . . . . . . . . . . . . . . . 72
2-6 X-wire probe geometry indicating geometry . . . . . . . . . . . . . . . . . . . . 72
2-7 Sample angle calibration plot . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
2-8 Forced Mass-Spring-Damper System . . . . . . . . . . . . . . . . . . . . . . . 73
2-9 Mass spring damper system FRF magnitude and phase . . . . . . . . . . . . . 74
2-10 PCB impulse hammer used in modal testing . . . . . . . . . . . . . . . . . . . . 75
2-11 Frequency response function of load cell . . . . . . . . . . . . . . . . . . . . . . 76
2-12 Final deconvolution filter frequency representation . . . . . . . . . . . . . . . . 77
2-13 Deconvolution filter FIR representation . . . . . . . . . . . . . . . . . . . . . . . 78
2-14 Filter correcting vibration from single impulse in different axes. . . . . . . . . . 79
2-15 Comparison of autospectra of hammer, unfiltered load and filtered load . . . . 80
2-16 Comparison of filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
2-17 Filter correcting vibration precession. . . . . . . . . . . . . . . . . . . . . . . . . 81
2-18 Filter correcting continuous forcing. . . . . . . . . . . . . . . . . . . . . . . . . . 82
2-19 Diagram indicating basic PIV procedure . . . . . . . . . . . . . . . . . . . . . . 83
2-20 Stereo PIV setup for chordwise measurements . . . . . . . . . . . . . . . . . . 83
2-21 PIV percentage deviation from U∞ for 500 averaged images in baseline flow . . 84
2-22 PIV percentage deviation from U∞ in turbulent flow . . . . . . . . . . . . . . . . 84
3-1 Baseline turbulence intensity downstream on tunnel centerline . . . . . . . . . 100
3-2 Variation of U∞ with rotational parameter λW . . . . . . . . . . . . . . . . . . . 100
3-3 Initial test autospectral density plot . . . . . . . . . . . . . . . . . . . . . . . . . 101
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