3/9/2007 10:48 AM 3/9/2007 10:48 AM 1 1 /27 /27 Experimental Investigations on DDT Experimental Investigations on DDT Enhancements by Shchelkin Spirals in a PDE Enhancements by Shchelkin Spirals in a PDE Philip Panicker Philip Panicker Graduate Research Associate, ARC, MAE, UT Arlington Graduate Research Associate, ARC, MAE, UT Arlington Co authors: Co authors: Dr. Daniel T. H. New, Dr. Daniel T. H. New, Lecturer, Mechanical Engineering, University of Liverpool, Liver Lecturer, Mechanical Engineering, University of Liverpool, Liver pool, UK pool, UK Dr. Frank K. Lu, Dr. Frank K. Lu, Professor, MAE, UT Arlington Professor, MAE, UT Arlington Dr. H. M. Tsai, Dr. H. M. Tsai, Principal Research Scientist, Principal Research Scientist, Temasek Laboratories, National University of Singapore Temasek Laboratories, National University of Singapore
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Experimental Investigations on DDT Experimental Investigations on DDT Enhancements by Shchelkin Spirals in a PDEEnhancements by Shchelkin Spirals in a PDE
Philip PanickerPhilip PanickerGraduate Research Associate, ARC, MAE, UT ArlingtonGraduate Research Associate, ARC, MAE, UT Arlington
Co authors: Co authors: Dr. Daniel T. H. New, Dr. Daniel T. H. New, Lecturer, Mechanical Engineering, University of Liverpool, LiverLecturer, Mechanical Engineering, University of Liverpool, Liverpool, UKpool, UK
Dr. Frank K. Lu, Dr. Frank K. Lu, Professor, MAE, UT ArlingtonProfessor, MAE, UT Arlington
Dr. H. M. Tsai, Dr. H. M. Tsai, Principal Research Scientist,Principal Research Scientist,Temasek Laboratories, National University of SingaporeTemasek Laboratories, National University of Singapore
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AgendaAgenda
IntroductionIntroductionReview of a few current and past PDE researchReview of a few current and past PDE researchExperimental MethodsExperimental MethodsResults of TestsResults of Tests
Effects of Shchelkin spiral blockage ratioEffects of Shchelkin spiral blockage ratioEffects of Schelkin spiral lengthEffects of Schelkin spiral lengthOperational IssuesOperational Issues
Video Clips of TestsVideo Clips of TestsA brief look at present workA brief look at present workConclusionConclusionQuestions from AudienceQuestions from Audience
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Air Breathing EnginesAir Breathing Engines
Mode of CombustionMode of Combustion
Deflagration / Deflagration / Subsonic Subsonic
CombustionCombustion
Supersonic Supersonic CombustionCombustion
Unsteady or Unsteady or Intermittent Intermittent CombustionCombustione.g. Pulse e.g. Pulse
e.g. Turbojets, e.g. Turbojets, Ramjets, RocketsRamjets, Rockets
Unsteady or Unsteady or Intermittent Intermittent CombustionCombustion
e.g. Pulse Jetse.g. Pulse Jets
Pulse Detonation Pulse Detonation RocketsRockets
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Deflagration vs. DetonationDeflagration vs. Detonation
DeflagrationDeflagrationDeflagration
1 to 10 m/sLow Speed Combustion
1 to 10 1 to 10 m/sm/sLow Speed Low Speed CombustionCombustion
Can be modeled asConstant Pressure
Process
Can be modeled asCan be modeled asConstant Pressure Constant Pressure
ProcessProcess
Decrease in Density, Slight Decrease in
Pressure
Decrease in Density, Decrease in Density, Slight Decrease in Slight Decrease in
PressurePressure
DetonationDetonationDetonation
1000s of m/sSupersonic Combustion
1000s of 1000s of m/sm/sSupersonic Supersonic CombustionCombustion
Modeled as Constant VolumeProcess
Shock wave followed by a thin Flame Front
Modeled as Modeled as Constant VolumeConstant VolumeProcessProcess
Shock waveShock wave followed by a thin followed by a thin Flame FrontFlame Front
Increase in Pressure, Density.Shock Wave compresses gas
Increase in Pressure, Density.Increase in Pressure, Density.Shock Wave compresses gasShock Wave compresses gas
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Advantages of Detonation over DeflagrationAdvantages of Detonation over Deflagration
The Humphrey cycleThe Humphrey cycle’’s Constant Volume heat addition process is more s Constant Volume heat addition process is more efficient than the Constant Pressure Brayton cycle.efficient than the Constant Pressure Brayton cycle.Rapid Energy ConversionRapid Energy ConversionCompact and Efficient Physical Systems.Compact and Efficient Physical Systems.Higher Exergy EfficienciesHigher Exergy Efficiencies
••Kailasanath, K., Kailasanath, K., Applications of Detonations to Propulsion: A ReviewApplications of Detonations to Propulsion: A Review, AIAA, AIAA--1999919999--10671067--366[1]366[1]
••Kailasanath, K., Kailasanath, K., Recent Developments in the Research on Pulse Detonation EnginesRecent Developments in the Research on Pulse Detonation Engines, AIAA 2002, AIAA 2002--04700470
••Bellini, R., Lu, F.K., Bellini, R., Lu, F.K., Exergy Analysis of a Hybrid Pulse Detonation Power DeviceExergy Analysis of a Hybrid Pulse Detonation Power Device, Energy, Energy--The International The International Journal, Submitted for review 2005Journal, Submitted for review 2005
1. DDT by means of High Energy Ignition Sources1. DDT by means of High Energy Ignition Sources
P1
DDT by Arc discharge, lasers or small DDT by Arc discharge, lasers or small amounts of explosives.amounts of explosives.
These methods are not practical and are These methods are not practical and are inefficient.inefficient.
The circuitry required for generating high The circuitry required for generating high voltage high amperage discharges are voltage high amperage discharges are heavy and bulky, and consume enormous heavy and bulky, and consume enormous amounts of energy.amounts of energy.
Deflagration to Detonation Transition (DDT)Deflagration to Detonation Transition (DDT)
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2. DDT by means of Flow Obstructions2. DDT by means of Flow Obstructions
P1
DDT is achieved by placing obstacles such as DDT is achieved by placing obstacles such as Shchelkin Spirals, grooves, dimples, etc., in Shchelkin Spirals, grooves, dimples, etc., in the flow path.the flow path.
This study used:This study used:
Shchelkin spiral, of different sizes.Shchelkin spiral, of different sizes.
Low energy automotive ignition spark.Low energy automotive ignition spark.
MultiMulti--cycle PDE rather than single shot cycle PDE rather than single shot experiments.experiments.
Stoichiometric Propane and OxygenStoichiometric Propane and Oxygen
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Past PDE Research at Past PDE Research at the ARCthe ARC
Experimental study of a pulse detonation rocket withSchelkin spiralF.K. Lu, J.M. Meyers, and D.R. Wilson, 2002
Propane+O2 mixture
5 to 20 Hz detonation cycles
Schelkin spiral
CJ detonation achieved briefly at low frequencies but not at the higher frequencies. This was attributed to improper mixing at higher frequencies.
Shchelkin SpiralShchelkin SpiralNamed after Russian Physicist Prof. K. I. Shchelkin, who proposed the spiral to bring about DDT in his 1965 book “Gas Dynamics of Combustion”.
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3. DDT in a 2 Stage PDE3. DDT in a 2 Stage PDE
2 Stage PDE
Liquid Fuel: JP-10, Hexane, Octane,Gasoline
Highly Detonable Mixture:H2+O2 or Propane+O2
Initiate detonation in a highly detonable mixture and then let tInitiate detonation in a highly detonable mixture and then let the detonation he detonation wave move into the larger combustion chamber holding fuel and aiwave move into the larger combustion chamber holding fuel and air mixture. r mixture.
The smaller detonation chamber is known as a preThe smaller detonation chamber is known as a pre--detonator.detonator.
2.3 304 34.7 5.4 1200 2350 15 3.4 No CJ detonation
3.2 304 46.2 3.6 1250 2350 55 12.4 No CJ detonation
3.5 304 49.8 3.6 2000 2350 100 22.5 No CJ detonation
4 304 55.6 3.1 2500 2350 120 27 PTs 2-3, 4-5
0 5940- base line
case 0 1200 2350 15 3.4 No CJ detonation
2.3 594 34.7 5.4 2500 2350 220 49.5 PTs 3-4
3.5 594 49.8 3.6 2500 2350 190 42.7 PTs 2-3, 4-5
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ConclusionsConclusionsEffect of BREffect of BR
Only the highest BR spiral showed sustained detonations.Only the highest BR spiral showed sustained detonations.The baseline case with no spiral showed an initial high pressureThe baseline case with no spiral showed an initial high pressure peak (~15 bars) followed by rapid decline in peak (~15 bars) followed by rapid decline in pressures. Similarly, the TOF velocities initially peak between pressures. Similarly, the TOF velocities initially peak between PT1 and PT2 at about 2500 PT1 and PT2 at about 2500 m/sm/s, but then shows a , but then shows a decreasing trend below CJ value.decreasing trend below CJ value.For the 55 % BR case, PT1 registers 15 bars and the successive PFor the 55 % BR case, PT1 registers 15 bars and the successive PTs show increasing or steady pressure levels, Ts show increasing or steady pressure levels, up to about 25 bars. TOF velocities also confirm a sustained detup to about 25 bars. TOF velocities also confirm a sustained detonation above CJ value.onation above CJ value.
Effect of Shchelkin spiral lengthEffect of Shchelkin spiral lengthWhen the spirals with smaller BRs are increased in length to 594When the spirals with smaller BRs are increased in length to 594 mm, detonation is found to occur, as seen from TOF mm, detonation is found to occur, as seen from TOF
velocities. velocities. The 35% BR case shows irregular pressure readings, with a peak aThe 35% BR case shows irregular pressure readings, with a peak at PT3 of about 40 bars. This corresponds with the t PT3 of about 40 bars. This corresponds with the
increase in TOF velocity which is higher than CJ only between PTincrease in TOF velocity which is higher than CJ only between PT2 and PT3. 2 and PT3. The 50% BR case shows a starting pressure reading of about 28 baThe 50% BR case shows a starting pressure reading of about 28 bars at PT1, with a rapid increase to 60 bars at PT2, rs at PT1, with a rapid increase to 60 bars at PT2,
after which it holds steady at about 25 bars. The TOF velocitiesafter which it holds steady at about 25 bars. The TOF velocities show detonations occurring between PT2 and PT3 show detonations occurring between PT2 and PT3 and also between PT4 and PT5. and also between PT4 and PT5.
Thus it may be concluded that shorter PDEs, which can run at higThus it may be concluded that shorter PDEs, which can run at higher frequencies due to their shorter her frequencies due to their shorter filling times, may use shorter Shchelkin spirals with higher BRsfilling times, may use shorter Shchelkin spirals with higher BRs to achieve detonations.to achieve detonations.
Longer PDEs, which have higher filling times and hence cannot ruLonger PDEs, which have higher filling times and hence cannot run at higher frequencies, can achieve n at higher frequencies, can achieve successful detonations using spirals with smaller BRs but with isuccessful detonations using spirals with smaller BRs but with increased lengths.ncreased lengths.
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Operational IssuesOperational IssuesMassive heating of the tube, leading to structural failure, shorMassive heating of the tube, leading to structural failure, shortened tened run times. On extended runs, the tube can be seen to enlarge andrun times. On extended runs, the tube can be seen to enlarge andwarp.warp.Destruction of Schelkin spiral. Effective spiral test time lastsDestruction of Schelkin spiral. Effective spiral test time lasts for only for only the first few seconds. the first few seconds. Heat affects the pressure transducer readings: Temperature driftHeat affects the pressure transducer readings: Temperature drift..PrePre--Ignition. When the tube gets hot, it continues to run with the Ignition. When the tube gets hot, it continues to run with the ignition cut off. This also results in improper filling of Tube ignition cut off. This also results in improper filling of Tube due to due to premature ignition. Results in irregular firing, loss of thrust premature ignition. Results in irregular firing, loss of thrust and and damage to equipment.damage to equipment.Ignition electrodes (Tungsten) wears away.Ignition electrodes (Tungsten) wears away.Ignition sparks cause tremendous amounts of EMI, which may Ignition sparks cause tremendous amounts of EMI, which may drown out the transducer signals. Therefore, reduce spark currendrown out the transducer signals. Therefore, reduce spark current t with appropriate resistors. Shield all cables and house DAQ in Ewith appropriate resistors. Shield all cables and house DAQ in EMI MI protected enclosure.protected enclosure.
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PDE Run videoPDE Run video BR = 46.2%; L = 304 mmBR = 46.2%; L = 304 mm
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Extremely high amounts of heat is generated. WaterExtremely high amounts of heat is generated. Water--cooling helps to cooling helps to extend the run time up to a minute.extend the run time up to a minute.
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Remains of the SS spiral after a test runRemains of the SS spiral after a test run
Electrodes experience Electrodes experience significant wear during the significant wear during the tests.tests.
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Questions??Questions??
References1. Kailasanath, K. “Recent developments in the research on pulse detonation engines,” AIAA Paper 2002-0470, 2002.2. Cooper M., Jackson, S., Austin, J., Wintenberger, E. and Shepherd, J.E. “Direct experimental impulse measurements for
detonations and deflagrations,” Journal of Propulsion and Power, Vol. 18, No. 5, pp. 1033-1041, 2002.3. Lee, S-Y, Watts, J., Saretto, S., Pal, S., Conrad, C., Woodward R. and Santoro R. “Deflagration to detonation transition
processes by turbulence-generating obstacles in pulse detonation engines,” Journal of Propulsion and Power, Vol. 20, No. 6, pp. 1026-1036, 2004.
4. Lu, F.K., Meyers J.M., and Wilson, D.R. “Experimental study of a pulse detonation rocket with Shchelkin spiral,” AIAA Paper 2003-6974, 2003.
5. Li, C., and Kailasanath, K. “A numerical study of reactive flows in pulsed detonation engines,” AIAA Paper 2001-3933, 2001.
6. He, X. and Karagozian, A.R. “Numerical simulation of pulse detonation engine phenomena,” Journal of Scientific Computing, 19(1-3):201-224, 2003.
7. Wintenberger, E., Austin, J.M., Cooper, M., Jackson, S. and Shepherd J.E. “An analytical model for the impulse of a single cycle pulse detonation engine,” AIAA Paper 2001-3811, 2001.
