Transcript Document

CONCEPTION OF MINICHANNEL AS
THE SOURCE OF SELF-IGNITION AT
HIGH SUPERSONIC SPEED
Goldfeld М.А., Starov А.V., Timofeev К.Yu.
Khristianovich Institute of Theoretical and Applied Mechanics
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Numerous scheme
of fuel injection and flame stabilization
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Fuel Injection at High Flight Mach Numbers
Consecutive fuel jets:
penetration increasing;
producing of stabilization zone;
mixing increasing;
drag decreasing
Wedge-shaped ramp injectors
Aero-ramp
Jacobsen L.S., Gallimore S.D., Schetz J.A., O’Brien W.F.:
Goss L.P., “Improved Aerodynamic-Ramp Injector in
Supersonic Flow”, AIAA Paper 2001-0518, January 2001
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AIMS of investigations:
 Development
of concept of the slotted channel (“heat generator”) for
ignition of hydrogen and stabilization of combustion under conditions of the
supersonic speeds of flow in the combustor (Mach numbers at entrance
M=4-6).
 Flow calculations in part of combustor with slotted channel for prediction
of flow parameters which favorable for hydrogen self-ignition.
 Definition of influence of Mach number on change of the flow structure in
the main channel, including two variants of slotted channel – with and
without critical section.
The subsequent experimental check of effectiveness of ignition of hydrogen
in the channel based on predicted distribution of temperature.
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Combustor model. Attached pipeline operating mode
Experimental
parameters at main
channel entrance
М=3.7, 4.9 and 5.8
P0=70 - 270bars
T0=1900 – 2600K
Scheme of combustor part with slotted channel
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Experimental and Calculation Investigations
Scheme of experimental channel
Computational area
Calculation parameters at inlet (1):
M=3.7 – static pressure P=1bar,
total temperature T0=1960K;
M=5.8 – P=0.34bar, T0=2050K
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Calculation Results
Flow Features in Slotted Channel
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Calculation Results
Static Temperature Increasing in Slotted Channel
M=5.8, without geometrical throat
1400
T, K
slotted channel
main flow
1200
1000
M=3.7, without geometrical throat
1400
T, K
slotted channel
800
600
main flow
1200
400
1000
200
800
0
0
600
0.05
400
0.15
0.2
0.25
0.3
x,0.35
m
M=5.8, with geometrical throat
1800
200
0.1
slotted channel
T, K
main flow
1500
0
0
0.05
0.1
0.15
0.2
0.25
0.3
x,0.35
m
1200
900
600
300
0
0
0.05
0.1
0.15
0.2
0.25
0.3
x,0.35
m
Distributions of static temperature along model channel
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Calculation Results
Static Pressure Distributions along Channel
M=5.8, without geometrical throat
1
P,
M=3.7, without geometrical throat
2.5
P,
0.8
slotted channel
0.4
slotted channel
2
main flow
0.6
main flow
bar
bar
0.2
1.5
0
0
0.05
0.1
0.15
0.2
0.25
0.3
x,0.35
m
1
M=5.8, with geometrical throat
3.5
P,
0.5
main flow
bar
slotted channel
3
0
0
0.05
0.1
0.15
0.2
0.25
0.3
x,0.35
m
2.5
2
1.5
1
0.5
0
0
0.05
0.1
0.15
0.2
0.25
0.3
x,0.35
m
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Experiment and Calculation Comparison at M=3.7
w/o geometrical throat
Schlieren and computational
visualization of density field
Schlieren
Calculation
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Experimental Results at M=3.7 w/o geometrical throat
Hydrogen flame in visible range
Phot/ P3 cold
bottom
top
2.5
Static pressure
distribution along
channel. Increasing at
combustion.
2
1.5
1
0.5
0
0
150
300
450
600
750
900
x, mm
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Experimental Results at M=3.7 with strut fuel injection.
Hydrogen flame in visible range
Phot/8Pcold
bottom
top
6
Static pressure
distribution along
channel. Increasing at
combustion.
4
2
0
0
150
300
450
600
750
900
x, mm
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Experimental Results at M=5.8.Two variant of process of ignition.
Without geometrical throat
With geometrical throat
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Experimental Results at M=4.9. Slotted channel modification.
Hydrogen flame in visible range
Phot/3.5
Pcold
bottom
3
top
2.5
Static pressure
distribution along
channel. Increasing at
combustion.
2
1.5
1
0.5
0
0
150
300
450
600
750
900
x, mm
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Conclusions
Numerical simulation of flow in the channel of the combustion chamber has shown that in the
slotted channel a deceleration of airflow and considerable increase of static temperature and
heat flux is observed.
Depending on internal geometry of the slotted channel (without or with a geometrical throat
at the exit section) is realized a supersonic or subsonic flow, accordingly. In both cases,
increase of temperature together with high level enough of static pressure in the channel leads
to hydrogen self-ignition in the slotted channel and to propagation of combustion into flow
core of the main channel that was confirmed by the experimental results.
The mechanism of combustion stabilization in these two cases was different.
In the first case, the hot flow of products of combustion from a nozzle of the slotted channel
extends into the main stream, and it leads to combustion propagation into the main channel
behind shock wave area.
In the second case, chocking of the slotted channel leads to emission of the combustion
products before an entrance. As a result, mass and heat transfer between the slotted and main
flow also intensifies and the further stabilization of combustion begins in the region of the
attached shock wave in recirculation area and behind the entrance of the slotted channel.
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