Development of a Compact Liquid Fueled Pulsed Detonation Engine with Pre-detonator Philip K. Panicker Aerodynamic Research Center, University of Texas at Arlington, Arlington, Texas, 76019 Jiun-Ming (Jimmy) Li Institute of Aeronautics and Astronautics, National Cheng Kung University, Tainan, Taiwan, 701, Republic of China Frank K. Lu Donald R. Wilson ARC, MAE Department, UT Arlington, Arlington, Texas, 76019 Acknowledgements: This study is made possible by funding from Mechanical and Aerospace Engineering Department, UT Arlington and The National Science Council, Taiwan, ROC 1
Agenda Past PDE research at ARC Objectives of present PDE design Pre-detonator 30 Smooth Area Change Nozzle Main Combustor Fuel and Gas Injection Valves Liquid Fuel-Air Mixing Chamber Diagnostics Complete Apparatus Test Program Conclusion 2
Past Detonation and PDE studies at ARC Stanley, Steven Bradley, "Experimental Investigation of Factors Influencing the Evolution of a Detonation Wave," Master's Thesis, Department of Mechanical and Aerospace Engineering, The University of Texas at Arlington, Arlington, TX, 1995. Burge, Karl Ramon, "Pulse Detonation - Detonation Continuance in Fuel-Air Regions," Master Thesis, Department of Mechanical and Aerospace Engineering, The University of Texas at Arlington, Arlington, TX, 1995. Munipalli, R., Shankar, V., Wilson, D.R., Kim, H., Lu, F.K., and Hagseth P.E. "A pulse detonation based mulitmode engine concept,"aiaa Paper 2001 1786, 10th AIAA/NAL/NASDA/ISAS International Space Planes and Hypersonic Systems and Technologies Conference, Kyoto, Japan, April 24 27, 2001 Wilson, D.R., Lu, F.K., Kim, H., and Munipalli, R., "Analysis of a pulsed normal detonation wave engine concept," AIAA Paper 2001 1784, 10th AIAA/NAL/NASDA/ISAS International Space Planes and Hypersonic Systems and Technologies Conference, Kyoto, Japan, April 24 27, 2001 Meyers, J. M., "Performance Enhancements on a Pulsed Detonation Rocket," Master's Thesis, Department of Mechanical and Aerospace Engineering, The University of Texas at Arlington, Arlington, TX, 2002. Presently there are Computational and Experimental studies on Pulse Detonation Engines and Applications at the ARC. 3
2000-2003 2003 Propane + O 2 mixture 5 to 20 Hz detonation cycles Shchelkin spiral High energy arc ignition Rotary valve system CJ detonation achieved briefly at low frequencies but not at the higher frequencies. This was attributed to improper mixing at higher frequencies. Lu, F.K., Meyers, J.M. and Wilson, D.R., Experimental study of propanefueled pulsed detonation rocket, AIAA Paper 2003 6974, 12th AIAA International Space Planes and Hypersonic Systems and Technologies, December 15 18, 2003, Norfolk, Virginia 4
High Energy Arc Ignition to Initiate Detonation Requires bulky electrical circuit components. Transformers, capacitor banks are heavy and impractical for flight weight model. Power generation to initiate arcs will deplete engine s available power output. Most of the power is wasted electrically when arc current flows to ground. Ignition plugs sustain heavy damage and have reduced life. The Arc is a big source of Electro-Magnetic noise that will drown out signals from transducers. 5
2003-2004 2004 Motor driven. (Motor is source of EMI and vibrations.) Belts slip and valves lose synchronicity. Need a sensor (magnetic pick up or optical transducer) to sense valve position. Very difficult to time ignition. Rotary valves leak and higher pressures are not possible. Therefore, stoichiometric mix or proper equivalence ratio not possible. Propane + Oxygen Higher frequency not possible. 6
2004-2005 2005 Propane + Oxygen Rotary Valve Automotive Ignition with Tungsten rod spark plugs Tested various Shchelkin spiral lengths, pitch, blockage ratio. Blockage Ratio of 50 to 55% most effective for DDT. Without water cooling, tube deforms, pre-ignition. Run time 10 seconds to 1 minute. Spirals break up in high pressure + temperature environment. 7
Late 2005 Propane + Oxygen 8
2006: Application of PDE for Electric Power Generation 9
Objectives of the New PDE Design Build a PDE platform to perform various structured studies Gaseous and Liquid Fuels, variable equivalence ratio, fill rates, etc. Long Duration Run Times (30 min. to 1 hour) High cycle frequency (0 to 100 Hz) Modular design, configurable easily for different test cases Low energy ignition Electrical solenoid valve injection Fully controllable via computer and monitor in real time 07 10
Compact Liquid Fueled PDE with Pre-detonator 07 11
Pre-detonator Fuel-Air mixtures have high DDT run up distance and initiation energy. Pre-detonator can shorten the run up distance and provide the energy required to drive the pressure wave to detonation. Thus, a low energy ignition source is sufficient. If spirals and DDT enhancing obstacles can be avoided, thrust is not lost due to drag. Small quantities of highly detonable mixtures are used to generate DDT within the main combustor. Smaller sized pre-detonators require less O 2 and fuel, as opposed to pre-detonator and main combustor having same area of cross-section. section. In hybrid PDE-Compressor Compressor-Turbine engines, the pre-detonator can get the engine started from full stop. Once the engine builds up speed, the pre-detonator may be cut off. 07 12
Why Propane? Propane is friendly coz we are from Texas, ya all all Already tested in prior studies, plenty of data available Major component of Natural gas Easy availability of propane in various containers. Viable as a fuel for commercial hybrid PDEs Cell sizes very similar to many liquid fuels, such as JP-10, with air. www.usepropane.com Copyright 2005 by the Propane Education & Research Council. www.buckandryan.co.uk www.propane-generators.com/ 07 13
Pre-detonator (contd.) Propane + Oxygen Low energy ignition Redundant spark plug Tangential gas injection Flanged Shchelkin spiral Can be run as a stand alone detonation tube, with the addition of an existing combustion chamber with pressure transducer ports 07 14
Pre-detonator (contd. 2) d c = 13λ for area abrupt area change d c = 26λ for D/D CJ 1.3 over-driven detonations 1 d c = 8.3 mm for propane/oxygen mixture 2 DDT was achieved in distances ranging from 5 to 25 cm for 1 in. diameter tube using propane-oxygen mixtures with varying equivalence ratio (1.6 to 0.85) 3 1 in. i.d. (25.4( mm/1.7 mm 15), length = 10 in. [1] Desbordes, D., Lannoy, A., Effects of a Negative Step of Fuel Concentration on Critical Diameter of Diffraction of a Detonation, Progress in Astronautics and Aeronautics, Vol. 133, 1991, pp. 170-186. [2] Schultz, E., Detonation Diffraction through an abrupt area expansion, PHD Thesis, California Institute of Technology, 2000. [3] Li, J., Lai, W.H., Chung, K., Tube Diameter Effect on Deflagration to Detonation Transition of Propane-Oxygen Mixtures, Shock Waves, Vol. 16, No. 2, December 2006, pp. 109-117. 07 15
Main Combustor Designed to be a stand alone detonation tube with the addition of an igniter The end flange allows extension of length or addition of other devices, e.g. a turbine. 07 16
Main Combustor Inlet Block (contd.) 07 17
Solenoid Valves Solenoid Valves and Electronic Fuel Injectors (1) 12 Vdc, 8A peak, 2A hold. Fast acting (2ms reaction time). Up to 35Hz tested successfully. 50Hz max. Easy and precise control possible using TTL signals from a remote computer. Max pressure 550 kpa (90psig) AFS-Gs60-05-5c series Fuel Valves Alternate Fuel Systems (2004) Inc. Calgary, Canada 07 18
Solenoid Valves and Electronic Fuel Injectors (2) Gasoline Direct Injectors Pressure rating of 14 MPa (2000 psi) Particle size of about 50 μm. DENSO CORPORATION Japan 07 19
Denso Driver Circuit 07 20
Denso Injector Water Test Water at 10 MPa. Measurement of Sauter s Mean Diameter (SMD) using Malvern Insitec Ensemble Particle Concentration and Size (EPCS) meter 07 21
Digital (TTL) Control of Valves and Ignition: Control Duty Cycle and Frequency Volts 50% Purge Air Valve Cycle Volts 40% Fuel, Oxygen Valves Cycle Volts 5% Ignition Control Cycle Time (s) 07 22
Liquid Fuel-Air Mixing Chamber 07 23
Liquid Fuel-Air Mixing Chamber (contd.) 07 24
Liquid Fuel Pump 07 25
Ignition System 150 mj max energy per spark Inductive Ignition System A transistor control circuit built in house enables the interfacing of the ignition system to the DAQ PC and allows ignition to be controlled remotely. 07 26
Schematic of the complete PDE Diagnostics. Dynamic pressure transducers (PCB 111A24 model, 1000 psi maximum, 450 khz resonant frequency) with water cooling adapters (064A01 recessed sensor and 064B02 flush sensor models) Load cells: piezo-electric PCB 201B03 (500 lbf) and 201B05 (5000 lbf) Photo-diode based optical sensors National Instruments DAQ consisting of a 1042Q chassis with two 8 channel 2.5 MS/s S-series PXI-6133 cards. The DAQ is connected to a remote PC via fiber optic cable which ensures smooth, EMI free signal transmission. PXI-6624 8 channel counter installed in the DAQ chassis that provides 8 configurable counters, enabling up to 8 devices to be precisely timed using the DAQ. LabVIEW is used to build all user interfaces. 07 27
Optical Sensor Hamamatsu photodiodes part number 1226-18BU), 1.1 mm square window sensitive to light between 190 and 1000 nm wavelengths 07 28
New PDE smell 07 29
Test Program Test frequency is set: 0 to 100 Hz Propane and Oxygen are injected simultaneously: varying equivalence ratio, fill volume Liquid fuel is mixed with air and injected: varying equivalence ratio, fill volume Ignition spark is fired, blow down Followed by purge Diagnostics can only be done for short periods, as long duration tests can damage sensors. Longer duration tests > 2 minutes, will be done with no PTs and only externally located sensors. Liquid Fuels: Jet A, Kerosene, JP-10, JP-4,etc. Also: propane-oxygen+ oxygen+ propane-air air 07 30
Future Studies PDE with liquid fuel + air test 1 minute to 30 minute duration Effect of interface location and area change on detonation wave 07 31
Conclusion A PDE platform capable of using liquid fuel with air, using a pre-detonator has been built. Cycle frequency, Equivalence ratios and Fill Rates can be controlled via solenoid valve timing and control of feed line pressure. Has integrated water cooling, expecting Long Duration Run Times (30 min. to 1 hour) High cycle frequency possible (0 to 100 Hz) Modular design, configurable easily for different test cases, addition of tube extensions, turbine, etc. Low energy ignition Can be fully controlled and monitored in real time via computer. 07 32