Development of liquid-fuel initiator for liquid-fuel PDE Tomoaki YATSUFUSA, Masahiro OHIRA, Shin ichi YAMAMOTO, Takuma ENDO and Shiro TAKI Hiroshima University Higashi-Hiroshima Japan 42nd Aerospace Science Meeting & Exhibit 5-8 January 2004 Reno, Nevada
Motivation Usage of Initiator in liquid-fuel-air PDE is one of the effective solution of detonation initiation. In addition, utilization of liquid fuel for the initiator as same fuel used in the main combustor is also beneficial. The effects of the conditions of liquid-fueloxygen mixture in the initiator to the detonation initiation of liquid-fuel-air mixture were investigated by using the liquid-fuel PDE at Hiroshima University.
Outline Motivation Outline Selection of liquid fuel Liquid-fuel PDE at Hiroshima University Experimental Conditions and Operation Experimental Results Discussion Conclusion
Objective Outline Selection of liquid fuel Liquid-fuel PDE at Hiroshima University Experimental Conditions and Operation Experimental Results Discussion Conclusion
White Gasoline White gasoline was chosen as the fuel for PDE Properties of white gasoline (Produced by Coleman) C n H 2n+2 (n=6-9) Composition Naphthene Aromatic Hydrocarbon Density 690 kg/m 3 Boiling temperature 333-413 K Firing temperature 243 K Ignition temperature 545 K 83% 12% 5% Evaporability (Boiling temperature) The requirements => as low as for Automotive Gasoline PDE (Evaporability and Detonability) Detonability (Ignition are temperature) satisfied => as low as Kerosene
Calculated detonation properties of normal octane at stoichiometric mixing n-oct. -O 2 n-oct. -Air Initial Condition To=298K, Po=0.1MPa Propagation velocity m/s 2344 1780 Pressure at CJ state MPa 3.83 1.76 Neumann spike MPa 7.84 3.37
Objective Outline Selection of liquid fuel Liquid-fuel PDE at Hiroshima University Experimental Conditions and Operation Experimental Results Discussion Conclusion
Liquid-fuel PDE at Hiroshima University Initiator Fuel Injector Igniter Rotary Valve 30 O2 Ion Probe Air 30 100 Fuel Injector (SMD<20µm) 35 2250 Main Combustor
Configuration of PDE and Air Tank Compressed Air Tank Liquid-Fuel PDE
(SMD<20µm) Fuel Injector Initiator V=100ml L=140mm O2 Injector 50 Igniter x4 140-570 Ii1 50 V=400ml L=570mm 50-440 30 Ii2 Ion probe
Whole View of Liquid-fuel PDE O 2, N 2, Air Bombs Air Tank Initiator Main Combustor
Objective Outline Selection of liquid fuel Liquid-fuel PDE at Hiroshima University Experimental Conditions and Operation Experimental Results Discussion Conclusion
Operation time chart Ignition IGN Initiator F-O IS IE Main Fuel MS ME Main Air 0 22 51 73 0 100 ms Rotary valve open
Operation time chart Ignition IGN Initiator F-O IS IE Main Fuel MS ME Main Air 0 22 51 73 0 100 ms Fuel-Air Introduction
Operation time chart Ignition IGN Initiator F-O IS IE Main Fuel MS ME Main Air 0 22 51 73 0 100 ms Fuel-Air Introduction
Operation time chart Ignition IGN Initiator F-O IS IE Main Fuel MS ME Main Air 0 22 51 73 0 100 ms Fuel-O 2 Injection
Operation time chart Ignition IGN Initiator F-O IS IE Main Fuel MS ME Main Air 0 22 51 73 0 100 ms Fuel-O 2 Injection
Operation time chart Ignition IGN Initiator F-O IS IE Main Fuel MS ME Main Air 0 22 51 73 0 100 ms Ignition
Operation time chart Ignition IGN Initiator F-O IS IE Main Fuel MS ME Main Air 0 22 51 73 0 100 ms Explosion
Operation Time Chart and Experimental Conditions Ignition IGN Initiator F-O IS IE Main Fuel MS ME Main Air 0 22 51 73 0 100 ms Initiator Initiator volume 100-400ml Injected mixture White gasoline and O 2 (φ=1.5) Injected volume of O 2 240-711ml/cycle Injection timing IS: 28-63ms, IE: 83ms Main combustor Supplied air volume 9.4L/cycle Injected mass of fuel 0.87g/cycle (φ=1.5) Fuel injection timing MS: 8ms, ME: 78ms Ignition timing IGN: 86ms
Objective Outline Selection of liquid fuel Liquid-fuel PDE at Hiroshima University Experimental Conditions and Operation Experimental Results Discussion Conclusion
Velocity measurement Oxygen Section 1-2 Section 3-4 385 150 300 150 Air Im1 Im2 Im3 Im4 385 535 835 985mm 2250 V D >1200m/s at section 3-4 : Initiation was succeeded
Effects of initiator volume and injected volume in detonation initiation Initiator volume [m l] 400 300 190 130 100 Initiated Critical Not Initiated 288 351 413 476 538 601 663 726 789 Injected Injected oxygen volume of into oxygen initiator [ml] [ml]
Effects of initiator volume and overflowed volume on detonation initiation (Overflowed volume) = (Volume of injected oxygen) (Initiator volume)
Effects of initiator volume and overflowed volume on detonation initiation Success rate 1.0 0.8 0.6 0.4 0.2 0.0 Initiator Volum eml 100 130 190 300 400 0 200 400 600 Overflowed volum e from initiator [m l] (Overflowed volume) = (Volume of injected oxygen) (Initiator volume)
Velocity at the section 1-2 (385-535mm) Velocity (1-2) [m /s ] 3000 2500 2000 1500 1000 50 0 0 Initiator Volume De t 130m l No de 130m l De t 400m l No de 400m l 100 200 300 400 500 Overflo we d volu m e from i niti ator [ml ] (Overflowed volume) = (Volume of injected oxygen) (Initiator volume) l l l l
Velocity at the section 3-4 (835-985mm) Velocity (3-4) [m /s ] 2500 2000 1500 1000 50 0 0 Initiator Volume De t 130m l No de 130m l De t 400m l No de 400m l 100 200 300 400 500 Overflo we d volu m e from i niti ator [ml ] (Overflowed volume) = (Volume of injected oxygen) (Initiator volume) l l l l
Flame propagation velocity in the initiator Velocity at initiator [m /s ] 3000 2500 2000 1500 1000 100 200 300 400 500 Overflowed volum e from initiator [m l] Initiator Volume Det 130ml No det 130ml Det 400ml No det 400ml (Overflowed volume) = (Volume of injected oxygen) (Initiator volume)
Effects of the overflowed volume Fuel Oxygen Igniter Air Fuel Detonation becomes weak at the sudden expansion part because of the rapid expansion of detonation front.
Effects of the overflowed volume w/o Overflowed Overflowed Fuel Fuel Igniter Igniter Oxygen Oxygen Air Fuel Air Fuel Detonation can not propagate at the sudden expansion section. Detonation is not decayed because of the overflowed volume. Thus, detonation can propagate to the fuel-air mixture
Conclusion (1) Determining factor of detonation initiation was the overflowed volume of liquid-fueloxygen mixture from the initiator to nearby the initiator exit. The PDE at Hiroshima University needs the overflowed volume of about 400ml to initiate the detonation of liquid-fuel-air mixture.
Conclusion (2) If overflowed volume of liquid-fuel-oxygen mixture from the initiator is large enough, detonation can propagate with minimum decay from the initiator to the main combustor. Accordingly, this is assumed to be the reason why the overflowed volume from the initiator is the determining factor to initiate the less detonable mixture in the main combustor.
Detonation Properties of White Gasoline Detonation properties are strongly affected by heat release and acoustic velocity of mixture. The difference of heat release in each composite of white gasoline is not so large. The properties can be estimated by that of a composite, such as octane.
Pressure History at Thrust Wall Overpressure [MPa] 12.0 10.0 8.0 6.0 4.0 2.0 0.0 No Det 130ml Det 400ml No Det 130ml 0.8 0.9 1.0 1.1 1.2 Time from ignition [ms] No Det 400ml Overflowed Volume: Det => 400ml, No Det => 200ml