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Transcript of Accademic conference
Flame Holding in the Recirculation Zone of Ducted Rockets
―The Effects of Zirconium Particle Addition―
Aeroapace Engineering MajorGraduate School of Science and Technology
Kuwahara and Tanabe Laboratory
Young Researchers’ Session on Aerospace Technology
S3-18
★ Kenro Obuchi
Takuo Kuwahara
Mitsuaki Tanabe
1 . BackgroundRocket engines needs to carry fuel and oxidizer .
Ducted RocketsThe air-breathing engines suited for supersonic flight.
Oxidizer is the oxygen in atmosphere.
Higher specific impulse than that of Rockets.
Fundamental Structure of a Ducted Rocket
Gas-Generator
Gas FlowNozzle
SupersonicAir-Intakes
Primary Combustor
Convergent-Divergent Nozzle
SecondaryCombustor
1. Background
A Fuel Rich Propellant
Fundamental Structure of a Ducted Rocket
Supersonic Flight ( Mach2~5 )
Fuel-Rich Gas
Air Ram-Air Combustion Gas
1. Background
Recirculation Zone
Air-Fuel Mixture
Mixture Gas Temperature Tm
1. Background
Ram-AirTa
Air-Fuel MixtureTm
Fuel-Rich GasTg
Gas-GeneratorComposition
Flight altitude and speed
Depending on flight conditions, the air-fuel mixture temperature can falls instantaneously
below spontaneous ignition temperature.
gas mixture Residence Time t r
1. Background
Gas-Flow Speedin the Secondary Combustor
ug=100~200 m/s
The gas mixture can be exhausted before ignite
Residence Timetr 10 ms≒
Ignition Sources
Ignition sources are needed to ignite the air-fuel mixture forcibly and continuously.
1. Background
Ignitable minute particle Minute particles were mixed into the gas generator and those were injected into the recirculation zone.
It is important to ignite and combust the air-fuel mixturein the recirculation zone
Minute particles addition1.
Background
Tem
pera
ture
T
Length
Gas Generator Ram-Air
Recirculation Zone
Tg: Fuel-Rich Gas
Tm: Air-FuelMixture
Tb: Burned Gas
Tu: Unburned Gas
Tp: Burned Gas
Spontaneoustemperature
Requirement for ignition sourcesT
empe
ratu
re T
Residence time and Chemical Delay Time
Particles are exhausted before ignite
Chemical Delay Timeτc
1. Background
Tg
Tm
Tp
Recirculation Zone
τc
Requirement for ignition sourcesT
empe
ratu
re
Chemical Delay Time
τc
1. Background
Recirculation Zone
Tg
Particles can ignite!
★Tm
Tp
Residence time and Chemical Delay Time
2. Objective
・ To clarify the possibility of minute particles being ignition source of the gas mixture.
3. Experiment
To select the most suitable minute particle for the ignition source, their chemical delay time τc
was obtained experimentally.
Candidates for the ignition source Zirconium (Zr), Titanium (Ti), Magnesium (Mg),
Almunium (Al), Boron (B)
Apparatus for measuring the ignition Delay Time
3. Experiment 1
minigig
pigc
cpig
ig
Electronic Furnace
Result3. Experiment 1
0
0.1
0.2
0.3
0.4
0.5
800 900 1000 1100 1200
Temperature in the Furnace, K
Che
mic
al D
elay
Tim
e, s
Zr 20( μm)
Ti(20μm)B(2μm)
Mg 20( μm)
4. Theoretical Analysis
The relationship between temperature history of particles cooled by gas mixture and the chemical delay time in the recirculation zone
was obtained theoretically.
Calculation conditions
Flight speed Mach 2.0
Flight altiture 11 km
Compression method Dual Lump
Limp Angle 10 degree
Ram air temperature, Ta 360K
Ram air pressure, Pa 0.1 MPa
Gas generator AP/HTPB Propellant
AP(Ammonium perchlorate) 65 wt%
HTPB(Hydroxyl-terminated polybutadien)
35 wt%
Combustor pressure, Pg 0.22 MPa
Hot fuel-rich gas temperature, Tg 1050 K
Air-fuel ratio stoichiometric ratio
4. Theoretical Analysis
Air Fuel-Rich Gas
gas mixture Particles
Air-fuel ratiostoichiometric ratio
7.4
Result4. Theoretical Analysis
600
700
800
900
1000
1100
1200
0 0.02 0.04 0.06 0.08
Residence Time and Chemical Delay time, s
Tem
pera
ture
, K
B
Ti
Mg
Zr
Tm
Tp
τc
ignite!
★
5.Conclusion
・ Zr particle has the highest ignitability, and the most suitable particle for an ignition source.