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National Aeronautics and Space AdministrationNational Aeronautics and Space Administration
Recent Combustion Control Test Results
John DeLaat NASA Glenn Research Center at Lewis Field, Cleveland, OH
[email protected], 216-433-3744
Acknowledgements:George Kopasakis, Joseph Saus, Clarence Chang,
D P Ch li W D V kDan Paxson, Changlie Wey, Dan Vrnak CE5 Test Cell Staff
NASA Management SupportNASA Aeronautics Program Support
Fundamental Aeronautics / SUP ProjectFundamental Aeronautics / SUP ProjectEnvironmentally Responsible Aviation Project
3rd NASA GRC Propulsion Control and Diagnostics Workshop
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3rd NASA GRC Propulsion Control and Diagnostics WorkshopFebruary 29, 2012
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National Aeronautics and Space Administration
Outline
• Active Combustion Control as an enabling technologyActive Combustion Control as an enabling technology to mitigate combustion instability
• Experimental Setup and ApproachExperimental Setup and Approach– Advanced, low-emissions combustor prototype
• Experimental Resultsp• Concluding Remarks and Future Directions
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National Aeronautics and Space Administration
Combustion Instability Control Strategyy gy
Objective: Suppress combustion thermo-acoustic instabilities when they occur
C b tC b ti
Closed-Loop Self-Excited System
Combustor Acoustics
CombustionProcess
Fuel air
Φ’
P’Natural feed-back processFuel-air
Mixturesystem
SensorControllerActuator
Artificial control process
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National Aeronautics and Space Administration
Active Combustion Instability Control Via Fuel Modulation
High-frequency fuel delivery system and models
•Acoustics•NL
•White Noise
•+•+•+
•Pressure fromC
•Instability Pressure
Advanced control methods
y
•Phase Shift•Controller
•Fuel •Valve
•Fuel lines, Injector•& Combustion •Flame
•+
Filt
•Fuel Modulation •Combustor PressureHigh-temperature sensors and electronics
•Filter
S d b k
Combustor Instrumentation (pressures, temp’s)
Physics-based instability models
Fuel InjectorEmissions Probe
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Realistic combustors, rigs for research
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Low Emissions Combustor Prototype with Observed Instability as installed in NASA CE5B Stand 1with Observed Instability, as installed in NASA CE5B-Stand 1
Range of Combustor Operating Conditions
2 1-element traversing probes65 – 250Inlet Pressure (psia)
5-element probe
dynamic pressure transducer, P4DynDn semi-infinite coil
approx. 100 –approx. 400Fuel Flow, lbm/hr
0.9 – 4.0Air Flow, lbm/s
400 – 1000Inlet Temperature, F
4DynDn,
d i t d P
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dynamic pressure transducer, P4DynUp, semi-infinite coil2 dynamic pressure transducers, P31,& P32
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Trend in Instability Amplitude vs. FARMultiple Test Conditions and RunsMultiple Test Conditions and Runs
1.2
psi
.
Run 905 - 135psia, 1000degF, 1.84pps, 10/90
Run 905 - 151psia, 1000degF, 2.05pps, 10/90
Run 905 - 151psia, 1000degF, 2.05pps, 20/80
1.2
psi
.
Run 905 - 135psia, 1000degF, 1.84pps, 10/90
Run 905 - 151psia, 1000degF, 2.05pps, 10/90
Run 905 - 151psia, 1000degF, 2.05pps, 20/80
0.8
1
nsta
bilit
y Fr
eq.,
p
Run 901 - 166psia, 1000degF, 2.26pps, 10/90
Run 906 - 166psia, 1000degF, 2.26pps, 10/90
Run 901 - 192psia, 950degF, 2.66pps, 10/90
Run 906 - 192psia, 950degF, 2.66pps, 10/90
Run 901 - 250psia, 1000degF, 3.4pps, 10/90
Run 905 250psia 1000degF 3 4pps 10/90
Suspect Data Point0.8
1
nsta
bilit
y Fr
eq.,
p
Run 901 - 166psia, 1000degF, 2.26pps, 10/90
Run 906 - 166psia, 1000degF, 2.26pps, 10/90
Run 901 - 192psia, 950degF, 2.66pps, 10/90
Run 906 - 192psia, 950degF, 2.66pps, 10/90
Run 901 - 250psia, 1000degF, 3.4pps, 10/90
Run 905 250psia 1000degF 3 4pps 10/90
Suspect Data Point
0.6
re A
mpl
itude
at I
n Run 905 - 250psia, 1000degF, 3.4pps, 10/90
Run 901 - 250psia, 1000degF, 3.4pps, 20/80
Run 905 - 250psia, 1000degF, 3.4pps, 20/80
0.6
re A
mpl
itude
at I
n Run 905 - 250psia, 1000degF, 3.4pps, 10/90
Run 901 - 250psia, 1000degF, 3.4pps, 20/80
Run 905 - 250psia, 1000degF, 3.4pps, 20/80
0.4
mbu
stor
Pre
ssur
0.4
mbu
stor
Pre
ssur
0
0.2Co
0
0.2Co
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0.0220 0.0240 0.0260 0.0280 0.0300 0.0320 0.0340 0.0360
Fuel/Air Ratio0.0220 0.0240 0.0260 0.0280 0.0300 0.0320 0.0340 0.0360
Fuel/Air Ratio
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Experimental Program Research Objectives
A. Replicate previously observed combustion instability behavior of the low-emissions combustor prototype;
B. Demonstrate combustion instability control and extend the combustor operating range into previously unstable regions;
C Determine if combustion instability control can be accomplishedC. Determine if combustion instability control can be accomplished using the dynamic pressure at P3 for feedback;
D. Determine if combustion instability control can be accomplished through modulation of the pilot fuel flow; and
E. Obtain dynamic characterization data for construction of a closed-loop version of the NASA Sectored 1-D combustor simulation as a pbenchmark problem.
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National Aeronautics and Space Administration
A. Comparison of Combustion Instability Behavior vs. Prior TestingPrior Testing
0.8 2
Instability peak at 620 Hz
0.6
0.7
e, p
si 1
1.5
psi
0.4
0.5
stor
Pre
ssur
e
0
0.5
psi
usto
r Pre
ssur
e, p
psi
0 1
0.2
0.3
Com
bus
-1
-0.5Com
bu
101 102 1030
0.1
Frequency, Hz1 1.01 1.02 1.03 1.04
-1.5
-1
Time, sec
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Combustor Pressure Amplitude Spectra Combustor Pressure Time History
P3=166psia, T3=1000degF, FAR=0.037, combustor ∆P/P=3%
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B. Demonstration of Combustion Instability Control
Low Emissions Combustor Prototype with Observed Instability as installed in NASA CE5B-Stand 1
Pressure Sensors
Combustor
Fuel Actuator (other side)
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B. Demonstration of Combustion Instability ControlCombustor Dynamic Pressure Response to Open-Loop Fuel Modulation of the Main injector
500 Hz 800 Hz
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B. Demonstration of Combustion Instability ControlClosed-Loop Self-Excited System
Fuel Valve
Combustor AcousticsFlame
Fuel-airMixture system
Natural feedback process
Phase ShiftController Filter
Sensed Combustor Pressure
Fuel Valve Command
ASPAC Algorithm
Adaptive Sliding PhasorAveraged Control (ASPAC)
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B. Demonstration of Combustion Instability Control
0.8
0.9
1.5
2
Adaptive Sliding Phasor Averaged Control (ASPAC) able to suppress combustion instability
Uncontrolled
0 3
0.4
0.5
0.6
0.7
mbu
stor
Pre
ssur
e, p
si
-0.5
0
0.5
1
psi
101 102 1030
0.1
0.2
0.3
Com
b
Frequency, Hz1 1.01 1.02 1.03 1.04
-2
-1.5
-1
Time, sec
Controlled94% d ti i k t0.6
0.7
0.8
0.9
re, p
si 1
1.5
2
94% reduction in peak at instability frequency
60% reduction in RMSEstimated ±8% of mean fuel
flow0.2
0.3
0.4
0.5
0.6
Com
bustor
Pre
ssur
-1
-0.5
0
0.5
psi
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101 102 1030
0.1
Frequency, Hz1 1.01 1.02 1.03 1.04
-2
-1.5
Time, sec
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B. Demonstration of Combustion Instability Control
Adaptive Sliding Phasor Averaged Control (ASPAC) able to prevent instability growth
Fuel/air ratio Filtered Combustor Pressure
Controller off0
1
2
Time RMS=0.54, Mean=0
0.036
0.038
0.04
0.042
Time RMS=0, Mean=0.04
-2
-1
0.03
0.032
0.034
Controller on1
2
Time RMS=0.11, Mean=0
0.038
0.04
0.042
Time RMS=0, Mean=0.04
-2
-1
0
0 03
0.032
0.034
0.036
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0 5 10 15 20 25 30 35 40-2
Time, sec0 5 10 15 20 25 30 35 40
0.03
Time, sec
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C. Combustion Instability Control with P3 Dynamic Pressure as Feedback
P3' ≤ 1300ºF 0.6
0.8
1
2
(upstream of fuel injector)
0.2
0.4
P3Dy
nA_p
si
-1
0psi
0 -2
P4' ≥ 3000ºF(downstream of fuel injector)
0.6
0.8
Dn_p
si
1
2
i
0
0.2
0.4
P4Dy
nD
2
-1
0psi
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101 102 1030
Frequency, Hz1 1.01 1.02 1.03 1.04
-2
Time, sec
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C. Combustion Instability Control with P3 Dynamic Pressure as Feedback
0.4
0.5
re, p
si
0 5
1
1.5
Uncontrolled
0.1
0.2
0.3
Com
bust
or P
ress
ur
1
-0.5
0
0.5
psi
101
102
103
0
Frequency, Hz0 0.01 0.02 0.03 0.04
-1.5
-1
Time, sec
Controlled85% d ti i k t0.3
0.4
0.5
ssur
e, p
si
0.5
1
1.5
85% reduction in peak at instability frequency
50% reduction in RMS0.1
0.2
Com
bust
or P
res
-1
-0.5
0psi
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101 102 1030
Frequency, Hz0 0.01 0.02 0.03 0.04
-1.5
Time, sec
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D. Combustion Instability Control Using Pilot Fuel Injector Modulation
• Advantage: Pilot carries only 20% of total fuel flow– Smaller fuel actuator, not lean-burn part of flame
j
– Possible downside: Smaller actuator authority, different part of flame
• Experimental Results:– Negligible response to pilot fuel modulations in combustor
• Optimizations attempted with the high-frequency valve– Shorten fuel feed line
O ti i l Fl N b– Optimize valve average Flow Number– Vary fuel feed line diameter (volume)– Stiffen valve mounting– Optimize valve internal return spring force– ...
– Conclusion: High-frequency valve is oversized for pilot• Was developed for higher-flow operation
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E. Closed-Loop Combustor Data for Development of Combustion Control Simulations
Perforated platePerforated plate
Blockage ratio = 0.83
P0' = 1.01
P4DynDn
Bl k
Blockage ratio = 0.83
P0' = 1.01 'u' = 0.005
P4DynDn
Bl k
CE5B-STAND 1 SIMULATION LAYOUT
P4DynUpFuel
airflowT0' = 1.00
28.4 in. 35.7 in.
Blockage ratio = 0.885
P4DynUpFuel
airflowT0' = 1.00
28.4 in. 35.7 in.
Blockage ratio = 0.885
www.nasa.gov1.34 in.
Water spray
1.34 in.
Water spray
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E. Closed-Loop Combustor Data for Development of Combustion Control Simulations
Combustion Instability Simulation Results Match Previous Experimental Results for Multiple Operating Conditions
1.4
si)
Exp -P3=250 psia T3=1000degF
0.8
1.0
1.2
nsta
bilit
y Fr
eque
ncy
(ps Exp.-P3=250 psia, T3=1000degF
Sim.-P3=250 psia, T3=1000degF
Exp.-P3=166 psia, 1000degF
Sim.-P3=166 psia, 1000degF
Frequency trend replicated0.4
0.6
4Dyn
Dn
Ampl
itude
at I
n
Amplitude trend replicated
0.0
0.2
0.024 0.025 0.026 0.027 0.028 0.029 0.03 0.031 0.032f/a Ratio
P
Amplitude trend replicated
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Concluding Remarks
Active control of combustion instability has been demonstrated for an advanced low-emissions aircraft engine combustor prototype:• The ASPAC algorithm can suppress an already existing instabilityThe ASPAC algorithm can suppress an already existing instability • The controller can also prevent instability growth, enabling high-power operation • A pressure sensor at P3 was used as a control feedback sensor • Instability control was demonstrated with main stage fuel modulation.Instability control was demonstrated with main stage fuel modulation.
– Pilot fuel modulation was investigated, but was unsuccessful due to inadequate fuel modulation strength.
Future plans:• Development of fuel actuators sized for pilot injectors• Development of feedback sensors able to operate at engine temperaturesp p g p• Extend existing simulation of uncontrolled combustion instability to include the
controlled case. • Apply combustion instability control technologies via pilot fuel modulation to
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increasingly advanced lean-burn combustors.