Iowa State University Capstones, Theses and Graduate Theses and Dissertations Dissertations 2020 Microwave enhancement of energetic materials combustion through gas-phase flame interactions Stuart James Barkley Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/etd Recommended Citation Barkley, Stuart James, "Microwave enhancement of energetic materials combustion through gas-phase flame interactions" (2020). Graduate Theses and Dissertations. 18277. https://lib.dr.iastate.edu/etd/18277 This Thesis is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Microwave enhancement of energetic materials combustion through gas-phase flame interactions by Stuart James Barkley A dissertation submitted to the graduate faculty in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Major: Mechanical Engineering Program of Study Committee: Travis R Sippel, Major Professor James B Michael Shankar Subramaniam Theodore J Heindel Jiming Song The student author, whose presentation of the scholarship herein was approved by the program of study committee, is solely responsible for the content of this dissertation. The Graduate College will ensure this dissertation is globally accessible and will not permit alterations after a degree is conferred. Iowa State University Ames, Iowa 2020 Copyright © Stuart James Barkley, 2020. All rights reserved. ii DEDICATION This dissertation is dedicated to my family, my friends, but most importantly my cats: Pabst, Stella, Bob, and Franklin iii TABLE OF CONTENTS Page LIST OF FIGURES .........................................................................................................................v LIST OF TABLES ....................................................................................................................... viii NOMENCLATURE ...................................................................................................................... ix ACKNOWLEDGMENTS ...............................................................................................................x ABSTRACT ................................................................................................................................. xi CHAPTER 1. INTRODUCTION .....................................................................................................1 1.1. Motivation ....................................................................................................................... 1 1.1.1. Solid Propellants ................................................................................................ 2 1.1.2. Pyrotechnics....................................................................................................... 3 1.1.3. A New Approach: Microwave Control of Energetic Materials ......................... 4 1.2. Literature Review ............................................................................................................ 6 1.2.1. Gas-Phase Microwave Plasma Enhancement .................................................... 6 1.2.2. Condensed-Phase Microwave Enhancement ..................................................... 7 1.2.3. Alkali Enhancement of Electron Populations .................................................... 8 1.3. Objectives ........................................................................................................................ 9 1.4. Document Organization ................................................................................................ 10 1.5. References ..................................................................................................................... 11 CHAPTER 2. EXPERIMENTAL METHODS ..............................................................................15 2.1. Microwave Cavities ...................................................................................................... 15 2.1.1. Single Mode Cavity ......................................................................................... 15 2.1.2. Multimode Cavity ............................................................................................ 19 2.2. Combustion Diagnostics ............................................................................................... 20 2.2.1. High-Speed Imaging ........................................................................................ 20 2.2.2. Two-Color Pyrometer Imaging ....................................................................... 20 2.2.3. Emission Spectroscopy .................................................................................... 24 2.2.4. Flame Emission Chromaticity ......................................................................... 26 2.2.5. Volumetric Gray Body Temperature Measurements ....................................... 27 2.2.6. Sodium Two-line Temperature Measurement ................................................. 28 2.3. Manufacture of Energetic Material Experimental Articles ........................................... 30 2.4. Chemical Equilibrium Calculations .............................................................................. 33 2.5. References ..................................................................................................................... 33 CHAPTER 3. MICROWAVE PLASMA ENHANCEMENT OF MULTIPHASE FLAME: ON- DEMAND CONTROL OF SOLID PROPELLANT BURNING RATES ....................................35 3.1. Abstract ......................................................................................................................... 35 3.2. Specific Aims ................................................................................................................ 35 3.3. Results and Discussion .................................................................................................. 36 iv 3.3.1. Equilibrium Chemical Calculations ................................................................. 36 3.3.2. Propellant Formulation Design ........................................................................ 39 3.3.3. Microwave Effects on Flame Structure and Plasma Formation ...................... 39 3.3.4. Microwave Effects on Flame Structure and Plasma Formation ...................... 43 3.3.5. Microwave Energy Partitioning and Burning Rate Enhancement ................... 46 3.4. Conclusion .................................................................................................................... 50 3.5. References ..................................................................................................................... 51 CHAPTER 4. MICROWAVE-ASSISTED MODULATION OF LIGHT EMISSION INTENSITY IN ALKALI-PYROTECHNIC PLUMES ...............................................................52 4.1. Abstract ......................................................................................................................... 52 4.2. Specific Aims ................................................................................................................ 52 4.3. Results and Discussion .................................................................................................. 53 4.3.1. Equilibrium Chemical Calculation .................................................................. 53 4.3.2. Microwave Effects on Flame Structure ........................................................... 54 4.3.3. VIS/NIR Spectral Emission Enhancement ...................................................... 56 4.3.4. Microwave Effects on Luminosity and Chromaticity ..................................... 60 4.3.5. IR Emission Enhancement............................................................................... 62 4.4. Conclusion .................................................................................................................... 63 4.5. References ..................................................................................................................... 64 CHAPTER 5. MICROWAVE SWITCHING OF A MAGNESIUM/TEFLON PYROTECHNIC FLAME COLOR, INTENSITY, AND TEMPERATURE ............................................................66 5.1. Abstract ......................................................................................................................... 66 5.2. Specific Aims ................................................................................................................ 67 5.3. Results and Discussion .................................................................................................. 67 5.3.1. Chemical Equilibrium Calculations ................................................................. 67 5.3.2. Spectral Emission Enhancement ..................................................................... 70 5.3.3. Microwave Effects on Flame Structure ........................................................... 72 5.3.4. Chromaticity and Luminosity Effects.............................................................. 73 5.3.5. Flame Temperature Measurements ................................................................. 76 5.3.6. Microwave Light Emission Enhancement Mechanism ................................... 80 5.4. Conclusions ..................................................................................................................