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

jdelaat@nasa.gov, 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

www.nasa.gov

3rd NASA GRC Propulsion Control and Diagnostics WorkshopFebruary 29, 2012

www.nasa.gov

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

www.nasa.gov

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

www.nasa.gov

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

www.nasa.gov

Realistic combustors, rigs for research

National Aeronautics and Space Administration

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

www.nasa.gov

dynamic pressure transducer, P4DynUp, semi-infinite coil2 dynamic pressure transducers, P31,& P32

National Aeronautics and Space Administration

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

www.nasa.gov

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

National Aeronautics and Space Administration

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.

www.nasa.gov

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

www.nasa.gov

Combustor Pressure Amplitude Spectra Combustor Pressure Time History

P3=166psia, T3=1000degF, FAR=0.037, combustor ∆P/P=3%

National Aeronautics and Space Administration

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)

www.nasa.gov

National Aeronautics and Space Administration

B. Demonstration of Combustion Instability ControlCombustor Dynamic Pressure Response to Open-Loop Fuel Modulation of the Main injector

500 Hz 800 Hz

www.nasa.gov

National Aeronautics and Space Administration

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)

www.nasa.gov

National Aeronautics and Space Administration

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

www.nasa.gov

101 102 1030

0.1

Frequency, Hz1 1.01 1.02 1.03 1.04

-2

-1.5

Time, sec

National Aeronautics and Space Administration

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

www.nasa.gov

0 5 10 15 20 25 30 35 40-2

Time, sec0 5 10 15 20 25 30 35 40

0.03

Time, sec

National Aeronautics and Space Administration

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

www.nasa.gov

101 102 1030

Frequency, Hz1 1.01 1.02 1.03 1.04

-2

Time, sec

National Aeronautics and Space Administration

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

www.nasa.gov

101 102 1030

Frequency, Hz0 0.01 0.02 0.03 0.04

-1.5

Time, sec

National Aeronautics and Space Administration

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

www.nasa.gov

National Aeronautics and Space Administration

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

National Aeronautics and Space Administration

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

www.nasa.gov

National Aeronautics and Space Administration

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

www.nasa.gov

increasingly advanced lean-burn combustors.