Practical Design Guidelines for Fugitive Gas Detection from Unmanned Aerial Vehicles

211 Pages·2017·10.66 MB·English

University of Colorado, Boulder
CU Scholar
Aerospace Engineering Sciences Graduate Theses &
Aerospace Engineering Sciences
Dissertations
Spring 1-1-2017
Practical Design Guidelines for Fugitive Gas
Detection from Unmanned Aerial Vehicles
William D. Tandy Jr.
University of Colorado at Boulder, [email protected]
Follow this and additional works at:https://scholar.colorado.edu/asen_gradetds
Part of theRemote Sensing Commons
Recommended Citation
Tandy, William D. Jr., "Practical Design Guidelines for Fugitive Gas Detection from Unmanned Aerial Vehicles" (2017).Aerospace
Engineering Sciences Graduate Theses & Dissertations. 191.
https://scholar.colorado.edu/asen_gradetds/191
This Dissertation is brought to you for free and open access by Aerospace Engineering Sciences at CU Scholar. It has been accepted for inclusion in
Aerospace Engineering Sciences Graduate Theses & Dissertations by an authorized administrator of CU Scholar. For more information, please contact
[email protected].
Practical Design Guidelines for Fugitive
Gas Detection from Unmanned Aerial
Vehicles

by
William D. Tandy Jr.
B.S., University of Texas at Austin, 2004
M.S., University of Texas at Austin, 2006

A thesis submitted to the
Faculty of the Graduate School of the
University of Colorado in partial fulfillment
of the requirement for the degree of
Doctor of Science
Department of Aerospace Engineering
2017
This thesis entitled:

Practical Design Guidelines for Fugitive Gas Detection from Unmanned Aerial Vehicles

written by William David Tandy Jr.
has been approved for the Department of Aerospace Engineering

William Emery

Jarett Bartholomew

Date

The final copy of this thesis has been examined by the signatories, and we
find that both the content and the form meet acceptable presentation standards
of scholarly work in the above mentioned discipline.
Tandy Jr., William (Ph.D., Aerospace Engineering)
Practical Design Guidelines for Fugitive Gas Detection from Unmanned Aerial Vehicles
Thesis directed by Professor William J. Emery
Abstract
Simulation, design, and analysis are combined in this effort to realize a UAV-scale instrument for fugitive
gas detection. The contributing material to the industry begins by extending and correlating an integrated
Gaussian plume model useful for instrument predictions and trade studies, regardless of the instrument
type or molecule of interest. A variety of generally applicable plots are produced from this foundation,
including receiver operator curves for leak rate detectability vs. wind speed, beam diameter vs. leak rate
detectability, and plots for required scan densities. The atmospheric and instrument parameter trade
studies are followed by hardware-specific analyses applicable to differential absorption lidar (DIAL)
instruments. A synopsis of the lessons learned from hands-on experiences in the lab further define the
design space for DIAL sensors. The dissertation culminates in the detailed design and analysis of two
DIAL instrument concepts. The conclusion is that a DIAL instrument capable of reliably detecting a 50
SCFH plume in winds speeds up to 7 mph is on the threshold of being achievable on a quadcopter
platform. Of special note is that the effort was funded by a Pipeline and Hazardous Materials Safety
Administration grant and performed in collaboration with Ball Aerospace & Technologies.

iii
Dedication

If you think you might even tangentially be someone I have leaned on while pursuing this dream, I
promise you that you were even more important than you realize. Thank you.

iv
Acknowledgments
Funding for this dissertation comes from the Pipeline and Hazardous Materials Safety Administration
Award DTPH5615HCAP11, Proposal 0415.07.0998B - Small-Scale DIAL for Methane Detection.

v
Table of Contents

Chapter 1: Introduction ................................................................................................................................. 1
1.1 Motivation ........................................................................................................................................... 1
1.2 Methane Overview .............................................................................................................................. 9
1.3 A Brief History of Gas Detection ..................................................................................................... 11
1.3.1 In Situ Devices ........................................................................................................................... 11
1.3.2 Lasers and Methane Sensing ...................................................................................................... 13
1.4 Dissertation Focus and Outline ......................................................................................................... 15
1.5 PHMSA Grant and Ball Collaboration ............................................................................................. 17
Chapter 2: Technical Foundations .............................................................................................................. 19
2.1 DIAL Technical Details .................................................................................................................... 19
2.2 UAV Platforms ................................................................................................................................. 22
2.2.1 Fixed-Wing UAVs ..................................................................................................................... 22
2.2.2 Quad-Copter UAVs.................................................................................................................... 24
2.3 Choosing a Laser Wavelength .......................................................................................................... 25
2.4 Pulsed vs. Continuous Wave ............................................................................................................. 28
2.5 Laser Technology .............................................................................................................................. 30
Chapter 3: Gaussian Plume Simulations ..................................................................................................... 31
3.1 The Gaussian Plume Model .............................................................................................................. 31
3.2 Extending the Gaussian plume model ............................................................................................... 33
3.3 Model Correlation with Field Measurement ..................................................................................... 35
vi
Chapter 4: Analysis Trade Studies .............................................................................................................. 42
4.1 Signal to Noise Ratio Calculation ..................................................................................................... 42
4.2 Choosing a Beam Diameter .............................................................................................................. 46
4.3 Impact of Error on Plume Area ......................................................................................................... 51
4.4 Quality of Measurement Sets ............................................................................................................ 53
4.5 Scan Pattern Considerations.............................................................................................................. 57
4.6 Influence of Beam Angle on Effective Beam Diameter ................................................................... 60
4.7 Speckle Considerations ..................................................................................................................... 62
Chapter 5: Wavelength-Based Reflectivity Variations ............................................................................... 69
5.1 Introduction ....................................................................................................................................... 69
5.2 Data ................................................................................................................................................... 72
5.3 Methodology ..................................................................................................................................... 76
5.4 Analysis Results ................................................................................................................................ 79
5.5 Example Applications ....................................................................................................................... 90
5.6 Summary ........................................................................................................................................... 93
5.7 Application to Methane at 1.645 µm ................................................................................................ 94
Chapter 6: Hardware Planning and Considerations .................................................................................... 97
6.1 Two Instrument Concepts ................................................................................................................. 98
6.2 Spectral Separation: Volume Bragg Grating..................................................................................... 99
6.3 Single Mode vs. Multimode Fiber .................................................................................................. 101
6.4 Beam Pickoff .................................................................................................................................. 104
vii
6.5 Minimizing Optic Count ................................................................................................................. 110
6.6 Beam Steering ................................................................................................................................. 110
6.7 Detectors ......................................................................................................................................... 114
6.8 Signal Measurement Via Integration .............................................................................................. 120
6.9 Analog to Digital Conversion, FPGA, and Storage ........................................................................ 127
6.10 Lessons Learned from Ball Hardware .......................................................................................... 128
Chapter 7: Baseline Design and Calculation ............................................................................................. 130
7.1 Goals and Requirements ................................................................................................................. 130
7.2 Design Process ................................................................................................................................ 130
Chapter 8: Final Hardware Design............................................................................................................ 133
8.1 Design Concept 1: Quad-Copter “Traditional” Instrument ............................................................ 133
8.2 Design Concept 2: Fixed-Wing “Traditional” Instrument with Scanning ...................................... 141
8.3 Design Concept 3: VBG Filtering ................................................................................................... 142
8.4 SNR Analysis .................................................................................................................................. 157
8.5 Leak Detection Performance ........................................................................................................... 161
8.6 Approximate Cost and Weight ........................................................................................................ 164
Chapter 9: Summary, Conclusions, and Next Steps ................................................................................. 168
9.1 Summary ......................................................................................................................................... 168
9.2 Conclusions ..................................................................................................................................... 173
9.3 Next Steps ....................................................................................................................................... 174
Bibliography ............................................................................................................................................. 176
viii
Appendix A: Cost and Weight Tables ...................................................................................................... 184

ix