ANALYSIS AND DESIGN OF A HYPERSONIC SCRAMJET ENGINE WITH A STARTING MACH NUMBER OF 4.00 by KRISTEN NICOLE ROBERTS Presented to the Faculty of the Graduate School of The University of Texas at Arlington in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE IN AEROSPACE ENGINEERING THE UNIVERSITY OF TEXAS AT ARLINGTON August 2008 Copyright © by Kristen Nicole Roberts 2008 All Rights Reserved ii ACKNOWLEDGEMENTS I wish to first thank my research advisor, Dr. Donald Wilson, for his guidance throughout the duration of this project. He provided a wealth of expertise from a diverse background of research, application of theory, and technical hands-on experience in addition to providing me encouragement throughout my research and my time at UTA. Additionally, I would like to thank Dr. Wilson, Dr. Roger Goolsby, Dr. Bernd Chudoba, and the Department of Mechanical and Aerospace Engineering for the financial support provided to me, as it was a great help towards the cost of my studies. I would like to thank Dr. Frank Lu for serving on my committee, as well as providing reference books, industry contacts, and technical expertise towards the completion of this project. I wish to thank Dr. Kent Lawrence for serving on my committee and for being an excellent professor to serve as a Graduate Teaching Assistant to for many semesters. His interest in my research and encouragement of its completion is much appreciated. I want to thank Dr. Bob Mullins of Bell Helicopter for his advice and insight in the planning stages of this project. I would also like to thank Dr. Bernd Chudoba for teaching me about conceptual design, his support and guidance in the AIAA conference papers I authored, and for the experience I gained in working on the contract work in the Aerospace Vehicle Design lab at UTA. Additionally, I would like to thank Paul iii Czysz for adding to my education through his wealth of experience and insight in hypersonic vehicle design. I wish to thank Bryan and Brad Mixon for all the laughs, technical help and advice, and the many sci-fi Fridays. I would like to thank Philip Panicker and the other members of the Aerodynamics Research Center for providing resources and contacts as necessary. I want to thank the fellow students with whom I worked in the AVD Lab, Dr. Xiao Huang, Gary Coleman, Amit Oza, and Nauman Mhaskar, for helping to make my time at UTA more enjoyable. I would like to also thank Mr. Rick Wild and the other engineers at the FAA in OKC as well as Mr. Russ Davoren for their support and encouragement during my Bachelor’s and Master’s degrees. I must gratefully acknowledge the constant support, love, and encouragement my family has provided to me, without which I would not be the person I am today. My mom is a constant source of inspiration and warmth, helping me to keep perspective; my dad set the foundation for the engineering spirit in me that seeks to constantly learn and the work ethic to make it happen; my brother has been a readily available no- nonsense source for advice and support. My late grandma Betty Reasoner and my grandpa Calvin Reasoner, my aunt and uncle Vicki and Steve Andrews, and my uncle Scott Kordis have been constant supporters of my work in many ways. And, lastly, to not acknowledge my lifelong friends would be to ignore my second family. I wish to thank Janell, Courtney, MaxAnne, Erin, Jandy, Charlotte, Andrea, Carissa, Melissa, Lacy, and Jennifer for their friendship, encouragement, iv advice, love, and support. Also, thank you to Jennifer and Sarah for the roundtable discussions and your friendship! And a special thanks to my dog Wilbur Wright, for staying up all those long nights with me! July 18, 2008 v ABSTRACT ANALYSIS AND DESIGN OF A HYPERSONIC SCRAMJET ENGINE WITH A STARTING MACH NUMBER OF 4.00 Kristen Nicole Roberts, MS The University of Texas at Arlington, 2008 Supervising Professor: Dr. Donald Wilson When pressures and temperatures become so high in supersonic flight that it is no longer efficient to slow the oncoming flow to subsonic speeds for combustion, a scramjet (supersonic combustion ramjet) is used in place of a ramjet. Currently, the transition to supersonic combustion generally occurs at a freestream Mach number around 5.0 to 6.0. This research details analysis completed towards extending scramjet operability to lower Mach numbers, while maintaining performance at higher Mach numbers within the same flowpath as detailed in the Air Force solicitation AF073-058. The specific goal is to determine whether the scramjet starting Mach number can be lowered to Mach 3.50 and, if not, what the constraints are that prohibit it and what the lowest possible starting Mach number for a scramjet is with today’s technology. This analysis has produced many significant insights into the current and required vi capabilities for both fuel and overall engine design in lowering the starting Mach number; these results are presented here. The analysis has shown that a scramjet with a starting Mach number of 3.50 is not currently possible with the fuels researched unless fuel additives or another addition to the system are used. However, a scramjet with a starting Mach number of 4.00 is possible with today’s existing technology. This paper has designed the engine flowpath for this case; its specifications and resulting performance are also detailed here. vii TABLE OF CONTENTS ACKNOWLEDGEMENTS....................................................................................... iii ABSTRACT .............................................................................................................. vi LIST OF ILLUSTRATIONS..................................................................................... xii LIST OF TABLES..................................................................................................... xvii LIST OF SYMBOLS AND ABBREVIATIONS...................................................... xxi Chapter 1. INTRODUCTION ....................................................................................... 1 1.1 Definition of a Scramjet Engine .............................................................. 1 1.2 Scramjet Engine Historical Timeline....................................................... 2 1.3 Applications for Scramjet Engines .......................................................... 6 1.4 Current Scramjet Engine Technology Challenges................................... 9 2. PROBLEM DESCRIPTION AND BACKGROUND .................................. 11 2.1 Problem Description and Scope of Current Work .................................. 11 2.2 Scramjets: Options for Lowering the Starting Mach Number................. 12 2.2.1. Variable Geometry.................................................................. 12 2.2.2. Hypersonic Dual-Combustor Ramjet (DCR).......................... 13 2.2.3. Manipulation of “Pure” Scramjet Engine Key Design Parameters .................................................................. 13 viii 2.3 Scramjet Reference Station Designations................................................ 14 2.4 Chapter Summary .................................................................................... 15 3. ANALYSIS OF KEY DESIGN PARAMETERS TO REDUCE SCRAMJET STARTING MACH NUMBER ............................................. 17 3.1 Theory and Equations ............................................................................. 19 3.1.1. Preliminary Calculation of Cycle Static Temperature Ratio T3/T 0 Necessary for Starting Mach Number of 3.50........................................................................ 19 3.1.2. Hypersonic Airbreathing Engine Performance Analysis Methods .................................................................... 20 3.1.3. Stream Thrust Analysis Method for Hypersonic Airbreathing Engine Performance Analysis ........................... 23 3.2 Analysis: Variation of Cycle Static Temperature Ratio .......................... 29 3.2.1. Influence: Impact on Lowering the Starting Scramjet Mach Number .......................................................... 29 3.2.2. Assessment: Feasibility of Mach 3.50 Starting Scramjet Today or in the Future.............................................. 31 3.2.3. Conclusion: Design Implications on a Lowered Starting Mach Number Scramjet .............................. 35 3.3 Analysis: Fuel Selection .......................................................................... 36 3.3.1. Influence: Impact on Lowering the Starting Scramjet Mach Number........................................................... 36 3.3.2. Assessment: Feasibility of Mach 3.50 Starting Scramjet Today or in the Future .............................................. 39 3.3.3. Conclusion: Design Implications on a Lowered Starting Mach Number Scramjet ............................................. 47 3.4 Analysis: Variation of Fuel-to-Air Ratio................................................. 49 ix 3.4.1. Influence: Impact on Lowering the Starting Scramjet Mach Number........................................................... 49 3.4.2. Assessment: Feasibility of Mach 3.50 Starting Scramjet Today or in the Future ................................ 50 3.4.3. Conclusion: Design Implications on a Lowered Starting Mach Number Scramjet .............................. 54 3.5 Chapter Summary and Conclusions......................................................... 58 4. DESIGN OF A SCRAMJET WITH STARTING MACH NUMBER OF 4.00 ........................................................................... 61 4.1