Combustion Dynamics and Control for Ultra Low … · Combustion Dynamics and Control for Ultra Low Emissions infor Ultra Low Emissions in Aircraft Gas-Turbine Engines John DeLaat

Combustion Dynamics and Control for Ultra Low Emissions in Aircraft Gas-Turbine Engines

Future aircraft engines must provide ultra-low emissions and high efficiency at low cost while maintaining the reliability and operability of present day engines. The demands for increased performance and decreased emissions have resulted in advanced combustor designs that are critically dependent on efficient fuel/air mixing and lean operation. However, all combustors, but most notably lean-burning low-emissions combustors, are susceptible to combustion instabilities. These instabilities are typically caused by the interaction of the fluctuating heat release of the combustion process with naturally occurring acoustic resonances. These interactions can produce large pressure oscillations within the combustor and can reduce component life and potentially lead to premature mechanical failures.

Active Combustion Control which consists of feedback-based control of the fuel-air mixing process can provide an approach to achieving acceptable combustor dynamic behavior while minimizing emissions, and thus can provide flexibility during the combustor design process. The NASA Glenn Active Combustion Control Technology activity aims to demonstrate active control in a realistic environment relevant to aircraft engines by providing experiments tied to aircraft gas turbine combustors. The intent is to allow the technology maturity of active combustion control to advance to eventual demonstration in an engine environment. Work at NASA Glenn has shown that active combustion control, utilizing advanced algorithms working through high frequency fuel actuation, can effectively suppress instabilities in a combustor which emulates the instabilities found in an aircraft gas turbine engine. Current efforts are aimed at extending these active control technologies to advanced ultra-low-emissions combustors such as those employing multi-point lean direct injection.

https://ntrs.nasa.gov/search.jsp?R=20110014458 2018-06-06T00:17:20+00:00Z

Combustion Dynamics and Control for Ultra Low Emissions infor Ultra Low Emissions in

Aircraft Gas-Turbine Engines

John DeLaatControls and Dynamics Branch

NASA Gl R h C t t L i Fi ld Cl l d OHNASA Glenn Research Center at Lewis Field, Cleveland, OHPh: (216) 433-3744, email: [email protected]

Graduate Seminar Series, The Ohio State UniversityMay 9, 2011

at Lewis FieldGlenn Research Center

Outline

• NASA’s Active Combustion Control interests

• Motivation: Ultra-low emissions, lean-burning, Multi-point Lean Direct Injection combustors – More susceptible to instability

• Possible approaches for dealing with combustor• Possible approaches for dealing with combustor thermo-acoustic instabilities

• Active Combustion Control as an enabling gtechnology

• Approach and outcomes of instability control i texperiments

• Future plans


Effect of Fuel Injection Schemes on NOx Emission

80

20

40

6080

MSV 9 inj, 60 oswMSV 9 inj, 45 oswMPIM-25 injMPIM-36 inj

T3=810K, P3=2760 kPa, ΔP/P=4%MP-LDI

/kg-

fuel

68

10

20N

Ox,

g-N

Ox/

2

4 Range of LPP data(Lean-Premixed-Prevaporized)

EIN

0.4

0.60.8

1Gaseous (LP)

Lean-Premixed

Flame Temperature, K

1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 24000.2

Courtesy of Bob Tacina


p ,

Conventional Combustion:Single-Point Rich Front End Injection

Φ~1

Dilutionzone

hot warm


Lean-Burning, Ultra-Low-Emissions Combustion:Multi-Point Lean Direct Injection

uniformlywarm

1. Energetic quick-mixing before auto ignition at high power condition

2. Lean and uniform front end makes less CO and NOx initially

3. Less CO initially, shorter combustor needed

4. Shorter combustor, shorter residence time, less additional NOx


Lean-Burning, Ultra-Low-Emissions Combustors Are More Susceptible to Thermoacoustic Instabilities

1. Higher performance fuel injectors => more turbulence

2. No dilution air => reduced flame holding

3. Reduced film cooling => reduced damping

4. More uniform temperature distribution => acoustically homogeneous

5 Shorter combustor => higher frequency instabilities

at Lewis FieldGlenn Research Center6

5. Shorter combustor > higher frequency instabilities

How do we deal with combustor instabilities?

1. Smart design2. Modulate air to get out-of-phase cancellation3. Fuel-modulation to get out-of-phase cancellation

Method 1 is preferred, but we’re not sure it’s enough

Method 2 requires lots of actuation power input and bulk

Method 2 also may induce diffuser flow separation due to flow perturbation.

Method 3 requires the least actuation power and bulkMethod 3 requires the least actuation power and bulk and produces the most energy change


Synergistic Technologies to Enable Ultra-Low Emissions CombustionUltra Low Emissions Combustion

Manufacturing

Fuel

Fuel Injection

D i

MaterialsProcesses

Ultra-Low

Emissions

Dynamics

and

Flameholding

Active

Combustion

Control

Combustion

Fuel Actuators

Methods

Facilities for

Realistic

T t C diti

Feedback

Sensors

Fuel Actuators

Combustor

and

Fuel System

Test Conditions


Dynamics

Combustion Instability

Combustor Combustion

Closed-Loop Self-Excited System

AcousticsProcess

Natural feed-back processFuel-air

Φ’P’

Natural feed back processMixture system


Combustion Instability Control Strategy

Objective: Suppress combustion thermo-acoustic instabilities when they occur

Combustor Combustion

Closed-Loop Self-Excited System

AcousticsProcess

Natural feed-back processFuel-air

Φ’P’

Natural feed back processMixture system

Artificial control process

SensorControllerActuator


Why is instability control so difficult?signal

Phase inversionsignalinversion-responsesum

Ti d l & h hiftTime delay & phase shift

Low signal-to-noise ratio – What frequency? What phase?

∆t

Low signal to noise ratio What frequency? What phase?


Our Technical Challenges

Control methods required to:• Control methods required to: – identify instability– suppress instability in presence of large time delay,

substantial noisesubstantial noise

• Combustor dynamics largely unmodeled

• Liquid fuel – introduces additional unmodeled dynamics including time delay (atomization, vaporization, …)

• Actuation system – enough bandwidth and authority not just• Actuation system – enough bandwidth and authority, not just valve (also feedline, injection, …)

• Experimental testbed for actuation, feedline dynamics required

• Simplified models needed for control design evaluation


Active Combustion Instability Control Via Fuel Modulation

High-frequency fuel delivery system and modelssystem and models

•Acoustics•NL

•White Noise •Instability Pressure

Advanced control methods

High-temperature sensors and electronics

•Phase Shift•Controller

•Fuel •Valve

•Fuel lines, Injector•& Combustion •Flame

•+•+•+

•Pressure from•Fuel Modulation •Combustor Pressure

sensors and electronics

Ph i b d i t bilit d l

Controller

•Filter

S d b k

Combustor Instrumentation (pressures, temp’s)

Physics-based instability models

Fuel InjectorEmissions Probe

Realistic combustors, rigs for research


Team Members - from Multiple Disciplines

• Controls and Dynamics Branch• Controls and Dynamics Branch– Dan Paxson: Dynamic Models– George Kopasakis: Control Methods– Joe Saus: Actuators

C b ti B h• Combustion Branch– Clarence Chang: Combustion Science

• Sensors and Electronics Branch– Robert Okojie: Harsh Environments Pressure Sensorsj

• Engineering Directorate– Dan Vrnak: Control Software

• Supersonics ProjectDan Bulzan Supersonics (and Subsonics) Combustion API– Dan Bulzan – Supersonics (and Subsonics) Combustion API

• Other NASA Participants– Materials, Combustion and Flow Diagnostics, Experimental Staff,…

• NRA Participants– Georgia Tech, Penn State, Virginia Tech – Other NRA's associated with Combustion Science


Control Strategies to Deal with Combustion Instability

• Objective– Perturb the fuel with the right amplitude and at the right phase to

cancel the instabilityy

• Challenges– Control action delay, noise, unknown disturbancesy, ,

• Approach– Use reduced-order models for developmentp– Use simplified physics-based model for validation before test

• Control methods– Empirical: Adaptive phase shifting based on achieved cancellation– Model-based: Set the proper phase for cancellation based on a

model of the predicted instability and disturbances


Adaptive phase shifting control:“Adaptive Sliding Phasor Averaged Control” – G. Kopasakis

P f

Pressure from Fuel modulation

Overall combustor pressure

AcousticsNL

Pressure from instability

Boundary of effective stability region

White Noise

++

Pressure from

Instability Pressure

Boundary of restricted control region

Fuel Valve

Fuel lines, Injector& Combustion Flame

++

Pressure fromFuel Modulation Combustor Pressure

Phase ShiftController


Filter

Motivation for Combustion Instability Simulation

• Successful active control design requires accurate modeling andsimulation.

–The essential physical phenomena should be correctly captured• (e.g. self-excitation).

–Characterization and control design necessitate rapid simulationCharacterization and control design necessitate rapid simulation• (i.e. relative simplicity).

–Simulation must lend itself to implementing a variety of sensing andactuation strategiesactuation strategies.

• The developed simulation method must achieve these goals forcombustor configurations:combustor configurations:

– in which the potential instabilities propagate axially

– that contain abrupt changes in cross sectional area


Combustion Dynamics Modeling

Detailed, physics-based dynamicSimplified Quasi-1DReduced-order oscillator Detailed, physics based dynamic models

Fundamental understanding of combustor dynamics to aid passive,

active instability suppression

Simplified Quasi 1D dynamic models

Allow physics-based control method validation

Reduced order oscillator models

Run fast to allow parametric studies in support of control

system development

vt: -130 -115 -100 -85 -70 -55 -40 -25 -10 5 20 35 50

10−4

10−2

100

i**2

/hz.

)

ComputedMeasuredCombustor

AcousticsCombustion

Process

−10

10−8

10−6

10−4

Pow

er D

ensi

ty (

psi*

*AcousticsProcess

Penn State Injector Response Model Plot

Results from NASA Sectored-1D Model of LPP C b t Ri

0 500 1000 1500 200010

−10

Frequency (hz.)


LPP Combustor Rig

Combustion Instability Simulation Features

• Time-accurate

• Physics-based, Sectored 1-D, Reacting

• Computationally efficient area transitions

Sector 3

Sector 1

p y

• Upstream and Downstream boundary conditions modeled to match rig

Sector 2

Sector 1

Injector Region

• One-Dimensional

• Perfect Gas

Within Each Sector: Combustor Region


Perfect Gas

Low Emissions Combustor Instability Model Development

Perforated platePerforated plate

CE5B-STAND 1 SIMULATION LAYOUT

airflow

Blockage ratio = 0.83

P0' = 1.01

T0' = 1.00

P4DynDn

Blockage ratio = 0.885airflow


P0' = 1.01

T0' = 1.00

'u' = 0.005

P4DynDn


P4DynUpFuel

0

28.4 in. 35.7 in.

Water spray

P4DynUpFuel

0

28.4 in. 35.7 in.

Water spray


1.34 in.1.34 in.

Combustion Instability Simulation Results Match Experimental Results for Multiple Operating Conditions

•1.0

•1.2

•1.4lit

y F

requ

ency

(ps

i) •Exp.-P3=250 psia, T3=1000degF

•Sim.-P3=250 psia, T3=1000degF

•Exp.-P3=166 psia, 1000degF

•Sim.-P3=166 psia, 1000degF

F t d li t d•0.4

•0.6

•0.8

ynD

n A

mpl

itude

at

Inst

abi

Frequency trend replicated

•0.0

•0.2

•0.024 •0.025 •0.026 •0.027 •0.028 •0.029 •0.03 •0.031 •0.032

•f/a Ratio

•P4D

y

Amplitude trend replicated


Fuel Delivery System Dynamic Response

PrimaryPrimaryFuel

SecondaryFuel

Stroboscopic Image of Dynamic Fuel Injection (courtesy UTRC)


Fuel Injection (courtesy UTRC)

High-Bandwidth Fuel Actuator Characterization Testing

Accumulator

P

Dynamic PressureTransducers

TestValve

P

Pump

PressurizedAir Volume

Valve, Feed-system Characterization Rig at NASA GRC


Steady-State Operational Data

High-Bandwidth Fuel Actuator

GaTech high-response fuel valve in characterization rig in CE7A

Frequency Response Dynamic Characterization Data

0.2

0

0.05

0.1

0.15

DP23

a/in

put, p

si/v

olt

360

-900

-720

-540

-360

-180

0

180

Pha

se, de

g

0ft-1V

1ft-1V

2ft-1V


-1080

0 500 1000 1500 2000 2500

Frequency, Hz

High-Bandwidth Fuel Actuator

300Hz 600Hz

Combustor Pressure Response to Fuel Modulation

1.5

olt

s

RefAcmd

Max=1.45 @ 600.59Hz, PSD RMS=1.3

Run 208, 020529 , Point 65

1

2

olt

s

Time RMS=1.06, Mean=0

1.5

olt

s

RefAcmd

Max=1.49 @ 300.29Hz, PSD RMS=1.3

Run 208, 020529 , Point 62

1

2

olt

s


0

0.5

1

Am

pli

tud

e, v

o

-2

-1

0

1

Am

pli

tud

e, v

o

0

0.5

1

Am

pli

tud

e, v

o

-2

-1

0

1

Am

pli

tud

e, v

o

0.2

0.3

0.4

itu

de,

psi

pla1c1

Max=0.25 @ 600.59Hz, PSD RMS=1.16

0

2

4

itu

de,

psi


0.4

0.6

0.8

itu

de,

psi

pla1c1

Max=0.55 @ 300.29Hz, PSD RMS=1.24

0

2

4

itu

de,

psi


0 500 10000

0.1

Am

pli

Frequency, Hz0 0.01 0.02 0.03 0.04

-4

-2

Am

pli

Time, sec0 500 1000

0

0.2

Am

pli

Frequency, Hz0 0.01 0.02 0.03 0.04

-4

-2

Am

pli

Time, sec


High Temperature Dynamic Pressure Sensors and Electronics

Newly developed 800oC sealing glass demonstrated on a dummy sensor and AlN package header.

Modified MEMS-DCA package to support 800˚C pressure sensor operation.

•30µm 1

2

V)

Output1 hour6519 hours

-2

-1

0

0 0 0 5 1 0

Sig

nal (

V

Input

6519 hours

T=500 °C

Diff amp test waveforms showing <5% change despite 6500 hrs at

500 °C

0.0 0.5 1.0Time (msec)

Differential amplifier circuit using two SiC transistors.

Design of SiC amplifier for dynamic pressure sensor.

at Lewis FieldGlenn Research Center 26

500 C. g dynamic pressure sensor.

Combustion Instability Control Test Implementation

• Control methodsSensed Combustor Pressure

• Control methods implemented in real-time computer

dS• Rig operated at nominal

engine temperature and pressure

dSpace Controls

Computer

pressure

Fuel ValveCommanded Fuel FlowFuel Supply


Active Combustion Instability Control Demonstrated Experimentally for Conventional Combustor

•8

•10

•12•pla1c1, Run 423 and 425, 040527 - 040603

Large amplitude, low-frequency instability suppressed by 90%

•4

•6

•Am

plitu

de, p

si

•100 •200 •300 •400 •500 •600 •700 •800•0

•2

•Frequency, Hz

0 4

Liquid-fueled combustor rig emulates engine observed instability behavior at engine pressures, temperatures, flows

•0.2

•0.25

•0.3

•0.35

•0.4

mpl

itude

, psi

•Open-loop•Adaptive Phase-Shift Control

High-frequency, low-amplitude instability is identified, while still small, and suppressed almost to the noise floor

•0 •100 •200 •300 •400 •500 •600 •700 •800 •900 •1000•0

•0.05

•0.1

•0.15

•Am

•Frequency Hz


suppressed almost to the noise floor. Frequency, Hz

Low-Emissions Combustor Prototype with Observed Instability

R f C b t O ti C diti•Range of Combustor Operating Conditions

•0.9 – 4.0•Air Flow, lbm/s

•400 – 1000•Inlet Temperature, F

•65 – 250•Inlet Pressure (psia)

•approx. 100 –approx. 400

•Fuel Flow, lbm/hr


Low-Emissions Combustor PrototypeInstability Amplitude Observed to Increase

with Increasing Fuel/Air Ratio

Increasing FAR0.1

Max=0.1 @ 525Hz5

Time RMS=0.59, Mean=-0.52

Page 1/1Run 901

with Increasing Fuel/Air Ratio

sure

0.025

0

0.05psi

-5

0psi

0.2Max=0.12 @ 525Hz

5Time RMS=0.58, Mean=-0.32

bust

or P

ress

0.0252

0

0.1psi

-5

0psi

1 5Time RMS=1.08, Mean=-0.14

Com

0.0281

0

0.5psi

Max=0.63 @ 536Hz

-5

0psi

2 5 Time RMS=1.52, Mean=-0.29

0.029

101

102

103

0

1psi

Frequency Hz

Max=1.05 @ 540Hz

0 0.01 0.02 0.03 0.04-5

0psi

Time, sec


Frequency, Hz ,

Trend in Instability Amplitude vs. FARfor Multiple Test Runs

1 21 2

1

1.2

req

., p

si

.

Run 905 - 135psia, 1000degF, 1.84pps, 10/90

Run 905 - 151psia, 1000degF, 2.05pps, 10/90

Run 905 - 151psia, 1000degF, 2.05pps, 20/80

Run 901 - 166psia, 1000degF, 2.26pps, 10/90

Run 906 - 166psia, 1000degF, 2.26pps, 10/90

1

1.2

req

., p

si

.

Run 905 - 135psia, 1000degF, 1.84pps, 10/90

Run 905 - 151psia, 1000degF, 2.05pps, 10/90

Run 905 - 151psia, 1000degF, 2.05pps, 20/80

Run 901 - 166psia, 1000degF, 2.26pps, 10/90

Run 906 - 166psia, 1000degF, 2.26pps, 10/90

0.8

e at

Inst

abili

ty F

r p , g , pp ,

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

Run 901 - 250psia, 1000degF, 3.4pps, 20/80

Suspect Data Point0.8

e at

Inst

abili

ty F

r p , g , pp ,

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

Run 901 - 250psia, 1000degF, 3.4pps, 20/80

Suspect Data Point

0.6

essu

re A

mp

litu

de

Run 905 - 250psia, 1000degF, 3.4pps, 20/80

0.6

essu

re A

mp

litu

de

Run 905 - 250psia, 1000degF, 3.4pps, 20/80

0.2

0.4

Co

mb

ust

or

Pre

0.2

0.4

Co

mb

ust

or

Pre

0

0.0220 0.0240 0.0260 0.0280 0.0300 0.0320 0.0340 0.0360

0

0.0220 0.0240 0.0260 0.0280 0.0300 0.0320 0.0340 0.0360


Fuel/Air RatioFuel/Air Ratio

Trend in Instability Frequency vs. FARfor Multiple Test Runs

570R 905 135 i 1000d F 1 84 10/90

560

Run 905 - 135psia, 1000degF, 1.84pps, 10/90

Run 905 - 151psia, 1000degF, 2.05pps, 10/90

Run 905 - 151psia, 1000degF, 2.05pps, 20/80

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

540

550

ity

Fre

qu

en

cy

, H

z

Run 901 - 250psia, 1000degF, 3.4pps, 10/90

Run 905 - 250psia, 1000degF, 3.4pps, 10/90

Run 901 - 250psia, 1000degF, 3.4pps, 20/80

Run 905 - 250psia, 1000degF, 3.4pps, 20/80

530

540

Pre

ssu

re In

sta

bil

i

520

Co

mb

us

tor

500

510

0.0220 0.0240 0.0260 0.0280 0.0300 0.0320 0.0340 0.0360


Fuel/Air Ratio

Low-Emissions Combustor Prototype with Observed Instability as installed in CE5B-Stand 1

Pressure Sensor

Combustor

Fuel Actuator (other side)


Low-Emissions Combustor - Instability Control ResultsAdaptive Sliding Phasor Averaged Control (ASPAC) able to suppress combustion instability

Uncontrolled

Combustor Pressure Amplitude Spectra Combustor Pressure Time HistoryRun 1018, Date 101123, Variable P4DynDn_psi Page 1/1

0.4

0.6

0.8

1

045

Max=0.84 @ 626Hz

0.5

1

1.5

2

2.5

psi

Time RMS=1.61, Mean=0.33

Controlled0 4

0.6

0.8

1

044

Max=0.05 @ 629Hz

-1.5

-1

-0.5

0

0.5

psi


0

0.2

-1

-0.5

0

Adaptive Sliding Phasor Averaged Control (ASPAC) able to prevent combustion instability

0

0.2

0.4

-3.5

-3

-2.5

-2

101

102

103

0

Frequency, Hz

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.041

Time, sec

-1

0

1

2


0 032

0.034

0.036

0.038

0.04

0.042

Time RMS=0, Mean=0.04

Fuel/air ratio Filtered Combustor Pressure

Controller off

p g g ( ) p y

Controller on

-2

0

1

2


0.03

0.032

0.034

0.036

0.038

0.04

0.042

Time RMS=0, Mean=0.04


0 5 10 15 20 25 30 35 40-2

-1

Time, sec0 5 10 15 20 25 30 35 40

0.03

0.032

0.034

Time, sec

Use P3’ (1000ºF) rather than P4’ (3000ºF+) as feedback?

0.5

0.6

0.7

Max=0.2 @ 626Hz

3

3.5


Run 1015, Date 101109, Point 122 Page 1/1

P3’

0.1

0.2

0.3

0.4

P3D

ynA

_psi

1.5

2

2.5

psi

P3

(upstream of fuel injector)

0 1

3.5

0.3

0.4

0.5

0.6

4Dyn

Dn

_psi

Max=0.57 @ 626Hz

2

2.5

3

psi


P4’

(downstream of fuel injector)

1 2 30

0.1

0.2

P4

Frequency, Hz

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.041

1.5

Time, sec


y

Future Plans

Mature and demonstrate active combustion control technologies– High temperature sensors, high-frequency fuel actuators and feed system

models, combustion dynamics models, control methods– Utilize Fundamentals rig in CE13C (5 atm) and medium/high pressure testing

in CE5 (30 atm) and ASCR (60 atm)

• Future platform(s) - LDI Multi-point injection and/or Industry advanced conceptsFuture platform(s) - LDI Multi-point injection and/or Industry advanced concepts

– Instability control demonstration(s) – 2012+

• Other potential advanced technologies

– Control methods that exploit multipoint injection– Multidimensional models– Incorporate technologies from Fundamental Aeronautics NRA’s

H i b h i d l d t l• Harmonic, sub-harmonic models and control• Flame Transfer Function models• Dynamic stability margin management• Static instability (LBO) detection and control


Long Term Goal for Active Combustion Control

I f d t l d t di f th• Improve fundamental understanding of the combustor processes

in order to…

More effectively integrate multi point combustor• More effectively integrate multi-point combustor design, controls, sensor, and actuator technologies

to provide…

• An intelligent fuel/air management system with• An intelligent fuel/air management system with temporal and spatial fuel modulation for– Instability avoidance/suppression

• Thermoacoustics, blowout– Pattern factor control– Emissions minimization

blto enable… Combustors with extremely low emissions

throughout the engine operating envelope


References• Paxson, D.: “A Sectored-One-Dimensional Model for Simulating Combustion Instabilities in Premix Combustors,” presented at the 38th

Aerospace Sciences Meeting & Exhibit. AIAA-2000-0313, NASA TM-1999-209771, January 2000.

• Cohen, J.M. et al: "Experimental Replication of an Aeroengine Combustion Instability," International Gas Turbine & Aeroengine Congress & Exhibition, Munich, Germany, ASME Paper 2000-GT-0093, May 2000.

• DeLaat, J.C.; Breisacher, K.J.; Saus, J.R.; Paxson, D.E.: “Active Combustion Control for Aircraft Gas Turbine Engines.” Presented at the 36th Joint Propulsion Conference and Exposition, Huntsville, Alabama, July 17-19, 2000. NASA TM 2000-210346, AIAA –2000-3500.

• Le, D.K.; DeLaat, J.C.; Chang, C.T.; Vrnak, D.R.: “Model-Based Self-Tuning Multiscale Method for Combustion Control.” Presented at the 41st Joint Propulsion Conference and Exhibit cosponsored by the AIAA, ASME, SAE, and ASEE, Tucson, Arizona, July 10-13, 2005. AIAA-2005-3593.

• Kopasakis, G.; DeLaat, J.; Chang, C.: “Validation of an Adaptive Combustion Instability Control Method for Gas-Turbine Engines,” 40th Joint Propulsion Conference and Exhibit, Ft. Lauderdale, FL, AIAA-2004-4028, NASA TM-2004-213198, October 2004.

• DeLaat, J.C.; Chang, C.T.: "Active Control of High Frequency Combustion Instability in Aircraft Gas-Turbine Engines," 16th International Symposium on Airbreathing Engines, Cleveland, OH, ISABE-2003-1054, NASA TM-2003-212611, September 2003.

• Cohen, J.M.; Proscia, W; and DeLaat, J.C.: “Characterization and Control of Aeroengine Combustion Instability: Pratt & Whitney and NASA Experience.” In “Combustion Instabilities in Gas Turbine Engines, Operational Experience, Fundamental Mechanisms, and Modeling”, AIAA Progress in Astronautics and Aeronautics series, Tim Lieuwen, Vigor Yang editors, Chapter 6, p. 113-145, October 2005.

• Okojie, R.S.; DeLaat, J.C.; Saus, J.R.: “SiC Pressure Sensor for Detection of Combustor Thermo-Acoustic Instabilities.” Presented at the 13th International Conference on Solid-State Sensors, Actuators and Microsystems, Seoul, Korea, June 5-9, 2005. Volume 1, p. 470-473.

• Kopasakis, G.; DeLaat, J.C.; Chang, C.T.: “Adaptive Instability Suppression Controls Method For Aircraft Gas Turbine Engine Combustors.” AIAA Journal of Propulsion and Power, Vol. 25, No. 3, May–June 2009, pp. 618-627.

• DeLaat, J.C.; Paxson, D.E.: “Characterization and Simulation of the Thermoacoustic Instability Behavior of an Advanced, Low Emissions Combustor Prototype.” Presented at the 44th Joint Propulsion Conference and Exhibit cosponsored by the AIAA, ASME, SAE, and ASEE, Hartford, Connecticut, July 21–23, 2008. AIAA-2008-4878, NASA/TM—2008-215291.

• Saus, J.R.; Chang, C.T.; DeLaat, J.C.; Vrnak, D.R.: “Design and Implementation of a Characterization Test Rig for Evaluating High Bandwidth Liquid Fuel Flow Modulators. Presented at the 45th Joint Propulsion Conference and Exhibit cosponsored by the AIAA, ASME, SAE, and ASEE, Denver, Colorado, Aug. 2-5, 2009. AIAA-2009-4886.


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Combustion Dynamics and Control for Ultra Low … · Combustion Dynamics and Control for Ultra Low Emissions infor Ultra Low Emissions in Aircraft Gas-Turbine Engines John DeLaat