THE DEVELOPMENT AND TESTING OF PULSED DETONATION ENGINE GROUND DEMONSTRATORS by PHILIP KOSHY PANICKER 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 DOCTOR OF PHILOSOPHY THE UNIVERSITY OF TEXAS AT ARLINGTON August 2008 Copyright © by Philip K. Panicker All Rights Reserved Psalm 53:1 (Please do not be one.) 2 Peter 3: 2-9 (Sign of the times.) Psalm 127:1 Except the LORD build the house, they labor in vain that build it: except the LORD keep the city, the watchman waketh but in vain. Mark 8:36, 37 For what shall it profit a man, if he shall gain the whole world, and lose his own soul? Or what shall a man give in exchange for his soul? Psalm 103:2-5 Bless the LORD, O my soul, and forget not all his benefits: Who forgiveth all thine iniquities; who healeth all thy diseases; Who redeemeth thy life from destruction; who crowneth thee with loving kindness and tender mercies; Who satisfieth thy mouth with good things; so that thy youth is renewed like the eagle's. Romans 10:13 For whosoever shall call upon the name of the Lord shall be saved. The Holy Bible, Authorized KJV ACKNOWLEDGEMENTS I would first like to thank Dr. Frank Lu for his long and continual support and encouragement throughout this educational endeavor. I am grateful for the freedom to pursue research in my own direction, mostly, and for the opportunity to work at the ARC. I also am thankful for the pep talks, the apt refocusing of my attention during wavering moments and for all the help with research. I am extremely indebted to Dr. Lu for his diligent editing and proofreading of my dissertation manuscript. I wish to thank Dr. Don Wilson, who helped me with my scholarships and assistantships and other aid during my study here. I am grateful to him for making it possible for me to travel to Canberra, Australia and Reno, NV, for the AIAA conferences. I am also very thankful for his advice on the research subjects and for reading and editing my dissertation. I want to thank Dr. George Emanuel for his advice and instructions during the brief time that he was on my committee. I would like to thank my committee members, Dr. Brian Dennis, Dr. Kamesh Subbarao and Dr. Albert Tong for their advice and feedback. I would like to thank Dr. J. Craig Dutton, who during his time here, encouraged me in my research work. I am also grateful to Dr. Wen S. Chan, who as graduate advisor, arranged for my teaching assistantships. In addition, I am obliged to Dr. S.M. You for granting me the opportunity to teach the MAE2381 class for two semesters. I would like to thank the administrative staff of the MAE department, including Louella Carpenter, Janet Gober, Sally Thompson, Barbara Sanderson and Donna Woodhead, for their timely management of all bureaucratic procedures and for all their help in maintaining the smooth flow of operations without a hitch. Connie Niece will always be remembered for her friendly words and for her help with travel arrangements. I would like to thank Rodney Duke, Engineering iv Technician at the ARC, who converted all the articles within my drawings and without into tangible material and for all other help in setting up our research apparatus. I wish to thank Jiun-Ming (Jimmy) Li, who was my research partner during his one-year stint here at UTA and ARC, during which time we drew up designs, performed experiments and wrote papers together. I want to thank Dr. Daniel T.S. New, who got me started on the research on PDEs and also took on the bigger role in writing papers of our research. I am also grateful to Kin Fong Chui and Kim Seng Lim, who joined us here for research on PDEs. I want to thank Naveen Kumar Reddy and Harsha Shivashankar, who were co-researchers on the early PDEs. I want to thank Rafaela Bellini, for her love, friendship and support for which I am truly indebted. I am grateful to her for wielding her great skills with MS Word for the formatting and typesetting of this manuscript and all other help she extended to me during my days writing this work. I am very grateful to Albert Ortiz, my colleague and co-researcher, for all his invaluable help and partnership in performing the experiments and setting up equipment and instruments, and analyzing data; and as co-GTA of MAE2381. I want to thank my other colleagues here at ARC, Eric Braun, Richard Mitchell, Adam Pierce and Prashaanth Ravindran, who helped with research work and in running the PDEs. Along with the other inhabitants of the ARC, they made life here interesting and fun. I want to thank my father P. Koshy Panicker, my mother Deenamma for their love, prayers and continued support for all my education. I also want to thank my brother, John, who supported me financially and spiritually in my education. I want to thank my sister, Anu Koshy and brother-in-law Binu John, for their love. I want to thank the Kuruvilla family for all their love, help and prayers during my life here in DFW. I want to thank all who helped me along the way and could not be included by name here in this short list. Above all, I want to thank my Lord and Savior Jesus Christ, who gave me life and blessed my life abundantly. May all glory be to God. July 23, 2008 v ABSTRACT THE DEVELOPMENT AND TESTING OF PULSED DETONATION ENGINE GROUND DEMONSTRATORS Philip K. Panicker, PhD. The University of Texas at Arlington, 2008 Supervising Professor: Frank K. Lu The successful implementation of a PDE running on fuel and air mixtures will require fast-acting fuel-air injection and mixing techniques, detonation initiation techniques such as DDT enhancing devices or a pre-detonator, an effective ignition system that can sustain repeated firing at high rates and a fast and capable, closed-loop control system. The control system requires high-speed transducers for real-time monitoring of the PDE and the detection of the detonation wave speed. It is widely accepted that the detonation properties predicted by C-J detonation relations are fairly accurate in comparison to experimental values. The post- detonation flow properties can also be expressed as a function of wave speed or Mach number. Therefore, the PDE control system can use C-J relations to predict the post-detonation flow properties based on measured initial conditions and compare the values with those obtained from using the wave speed. The controller can then vary the initial conditions within the vi combustor for the subsequent cycle, by modulating the frequency and duty cycle of the valves, to obtain optimum air and fuel flow rates, as well as modulate the energy and timing of the ignition to achieve the required detonation properties. Five different PDE ground demonstrators were designed, built and tested to study a number of the required sub-systems. This work presents a review of all the systems that were tested, along with suggestions for their improvement. The PDE setups, ranged from a compact PDE with a 19 mm (3/4 in.) i.d., to two 25 mm (1 in.) i.d. setups, to a 101 mm (4 in.) i.d. dual-stage PDE setup with a pre-detonator. Propane-oxygen mixtures were used in the smaller PDEs. In the dual-stage PDE, propane- oxygen was used in the pre-detonator, while propane-air mixtures were used in the main combustor. Both rotary valves and solenoid valve injectors were studied. The rotary valves setups were tested at 10 Hz, while the solenoid valves were tested at up to 30 Hz on a 25 mm i.d. PDE. The dual-stage PDE was run at both 1 Hz and 10 Hz using solenoid valves. The two types of valves have their drawbacks and advantages which are discussed, along with ways to enhance their functionality. Rotary valves with stepper motor drives are recommended to be used for air flow control, while an array of solenoid injectors may be used for liquid or gaseous fuel injection. Various DDT enhancing devices were tested, including Shchelkin spirals (with varying thicknesses, lengths and pitches), grooved sleeves and converging-diverging nozzles. The Shchelkin spirals are found to be the most effective of all, at blockage ratios in the region of 50 to 55 %. To improve the durability of Shchelkin spirals, it is recommended that they be grooved into the inside of tubes or inserted as replaceable sleeves. Orifice plates with high blockage ratios, in the region of 50 to 80 %, are also recommended due to their simple and rugged design. All these devices along with the PDE combustor will require a strong cooling system to prevent damage from the extreme detonation temperatures. High energy (HE) and low energy (LE) ignition systems were tested and compared along with various designs of igniters and automotive spark plugs. It is concluded that while HE ignition may help unsensitized fuel-air mixtures to achieve detonations faster than LE systems, the former have severe drawbacks. The HE igniters get damaged quickly, and require large and heavy power vii supplies. While the HE ignition is able to reduce ignition delay in a propane-oxygen pre- detonator, it did not show a significant improvement in bringing about DDT in the main combustor using propane-air mixtures. The compact pre-detonator design with a gradual area change transitioning to a larger combustor is found to be effective for detonation initiation, but the pre-detonator concept is recommended for high-speed applications only, since higher speeds requires more sensitive, easily detonable fuels that have short ignition delays and DDT run-up distances.