National Aeronautics and Space Administration Low ... · National Aeronautics and Space Administration Low-Emissions Combustors Development and Testing Dr. Clarence T. Chang …

National Aeronautics and Space Administration

Low-Emissions Combustors Development and Testing

Dr. Clarence T. Chang

www.nasa.gov

NASA Glenn Research [email protected] borrowed from GE


Outline

• Aeroengine combustor designAeroengine combustor design process is tough (“optimum compromise”)

• What’s optimized• How to test/validate

The emissions challenge• The emissions challenge• The resulting dynamics challenge• Active Control as a response toActive Control as a response to

the dynamics challenge

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Balanced Combustor Design

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Viewgraph borrowed from GE


Some Typical Operating Parameters

Parameters Take-Off Cruise

PRO All 30 45 30PROverAll 30-45 30

P3 450-675 psia 150 psia

T3 1000 - 1300 °F 800 °F

T4 2400 - 3000 °F 1800 °F

OverAll 0.30 - 0.5 0.25

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How do we assess performance?

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NASA Glenn Combustor FacilitiesFlametube => Sector => Annular

Non-Facility Config.

Pres. range, psig

Max. airflow, lb/sec

Non-vitiated

heated air, ˚F

Max. exhaust temp., ˚F

CE–5B-1 Sector 60 to 275 2 to 12 500 to 1350 3200

CE–5B–2 Flametube 60 to 400 0.6 to 5 500 to 1350 3200

ASCR Leg 1 Sector / annular

50 to 900 3 to 50 500 to 1200 3400annular

ASCR Leg 2 Flametube 50 to 900 1 to 10 500 to 1200 3400

0 60 3 0

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CE-13C Flametube 0-60 0.8 1000 3550


CE5B Stand 1 Flametube / sector (1200 °F 450 psi 30 lbm/s air flow)CE5B Stand 1 Flametube / sector (1200 F, 450 psi, 30 lbm/s air flow)Newer – Dynamics testingNewest – Alternate Fuels

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ASCR Stand -1 60 atm Sector Testing Rig.1300 °F 900 psi 50 lbm/s airflow1300 F, 900 psi, 50 lbm/s airflow

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CE-13C LDI Injector Screening Rig Functional Layout (laying on its side)1000 °F, 60 psig, 0.8 lbm/s airflow, p g,

Variable-fueled Fuel in Quench

WaterModulating

valve

Variable-fueled Fuel in Quench

Water

Dynamic Pressure Sensors Water

invalve Water

in

HeatedAir in

Exhaustout

HeatedAir in

3-in ID WindowedTest section Nearly-chokedFlow3-in ID WindowedTest section Nearly-chokedFlow

ChokedOutletIsolatorEmissions

Sampling

for visualizationFuel injectorInstallationh d

Inlet isolatorConditionscreens

CatalyticReactor

ChokedOutletIsolatorEmissions

Sampling

for visualizationFuel injectorInstallationh d

Inlet isolatorConditionscreens

CatalyticReactor

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SamplingInstrumentationFlange

hardwareNot drawn to scale

SamplingInstrumentationFlange

hardwareNot drawn to scale


How does a combustor work?

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Legacy Combustor Features

1 Diffuser slows down

2 Fuel nozzle turbulence5. Primary dilution holes provides dilution

1. Diffuser slows down flow speed to reduce Rayleigh loss

2. Fuel-nozzle turbulence speeds up atomization by break up liquid into droplets3 Liner film-cooling

4. Swirling flow forms i l i

holes provides dilutionand vortex anchor

6. Secondary dilution holes add more air to bring T4 down

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3. Liner film cooling decouples thermal loadingfrom pressure casing

recirculation vortex to provide flame-holding

add more air to bring T4 down and shape T4 profile


Where Does Pollution Come From?

ModerateTemperature

High-Temp.Z

Rich CO, uHC Temperature

Dilution Zones- More NOx

Zones –NOx

,soot

FrozenChemistry

SOx &

Chemistry

SOx &aerosols

uHC near liner TurbineStatorS t d CO

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StatorSoot and COoxidation


And NASA Combustor Programs

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NOx Formation Concept and Avoidance Strategy

NOxNOxFormationRate(HighlyT t x Residence

ti =ObNOxious

outputTemperatureDependent)

x time output

Key to Low-NOx:1 A id hi h t t b i

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1. Avoid high temperature burning2. Keep the exposure time short


NOx Reduction Combustor Concepts

RQL** Partial-Pre-Mixed* LDIQ

Lean-burn

Rich-burn

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**McKinney, 2007*Dodds, 2008


Lean-burn Fuel Staging Enables Low NOx at Cruise

NOx flight cycle comparison (GE TAPS vs. traditional RQL combustor)

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Lean Direct Injection – Low NOx Concept

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Current LTO NOx Emissions

kN120

140

CAPE/4 Engine > 89.4 kN

/kN

100PW4090

PW4098

/ CAPE/4 Engine=26.7kNCAPE/6

F oo (N

Ox)

, g/

60

80

C CFM56 7B24

CFM56-7B26

CFM56-7B27

GE90-115BGE90-113B

GE90-110B1

GE90-94B

GE90-92BGE90-90B

GE90-85B

GE90-77BTrent 877

Trent 884

Trent 892

Trent 895

Trent 970-84PW4074

PW4077

PW4077DPW4084

PW4084D

PW4168 C

CAPE/2 / CA

GEnx -1B 55% below CAEP 6

RR Trent 1000 ~50% below CAEP 6 (Predicted)

PW 810 ~50% below CAEP 6

Dp/

F

40

CFM56-7B20CFM56-7B22 CFM56-7B24

PW4164

PW4168AE3007A1

AE3007A3

AE3007CAE3007C1

CFM56-5B2/3CFM56-5B3/3

CFM56-5B7/3

CFM56-5B8/3CFM56-5B9/3CFM56-7B18/3

CFM56-7B20/3 CFM56-7B22/3CFM56-7B24/3

CF34-10E7

CF34-10E6CF34-10E2A1CF34-8E6A1

CF34-8E6

CF6-80C2A5

CF6-80C2B1

CF6-80E1A4 PW 810 50% below CAEP 6 (Estimated)

NASA N+2

0

20NASA N+2

Borrowed from Coen, 2009 ICAO

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Engine Pressure Ratio

15 20 25 30 35 40 45 50 55 60


Effect of Fuel Injection Schemes on NOx Emission

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Why do we need combustor control?

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Issues that Affect Combustor Instability / Acoustics

Diffuserplenum fuel

injectorswirlvanes primary secondaryliner

fil

turbinestator

1. Well-defined acoustic b d diti

3. Recirculation 5. Multiple

vanesdilutionholes

dilutionholes

filmcooling

boundary conditions

2. Perturbations from fuel- 4. Liner film-cooling

vortex provides flame-holding

temperature zones

6. Φ’ interaction

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nozzle turbulenceg

provides damping with P’


Lean-Burning, Ultra-Low-Emissions Combustors A M S tibl t Th ti I t bilitiAre More Susceptible to Thermoacoustic Instabilities

1. Higher performance fuel injectors => more turbulence2. No dilution air => reduced flame holding3. Reduced film cooling => reduced damping4. More uniform temperature distribution => acoustically homogeneous

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p y g5. Shorter combustor => higher frequency instabilities


How do we deal with combustor instabilities?

1. Smart design2. Modulate air to get out-of-phase cancellation2. Modulate air to get out of phase cancellation3. Fuel-modulation to get out-of-phase cancellation

HoweverHowever…

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 toflow perturbation.flow perturbation.

Method 3 requires the least actuation power and bulk andproduces the most energy change.

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Combustion Instability Control Strategy

Objective: Suppress combustion thermo-acoustic instabilities when they occur

CombustorCombustion

Closed-Loop Self-Excited System

Combustor Acoustics

CombustionProcess

Natural feed-back processFuel-air

Φ’

P’Natural feed-back processMixture

system

A tifi i l t l

SensorControllerActuator

Artificial control process

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Why is instability control so difficult?

Phase inversionsignal

inversion-response

sum

Time delay & phase shift

Low signal to noise ratio What frequency? What phase?

Δt

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

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

Manufacturing

Fuel

Fuel InjectionD i

MaterialsProcesses

Ultra-Low Emissions

Dynamicsand

FlameholdingActive

Combustion Control

Combustion

F l A t t

Methods

Facilities for Realistic

T t C diti

FeedbackSensors

Fuel ActuatorsCombustor

andFuel System

Test Conditions

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Dynamics


Observations

• Small changes can affect major behavioral change• Combustor should not be considered oneCombustor should not be considered one

homogeneous medium

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References

1 A th H L f b G T bi C b ti 2 d Ed T l & F i 19991. Arthur H. Lefebvre, Gas Turbine Combustion, 2nd Ed., Taylor & Francis, 1999.2. Dodds, Will, Engine Technology Developments to Address Local Air Quality Concerns,

International Coordinating Council of Aerospace Industries Associations, 20083. Dodds, Will, Twin Annular Premixing Swirler (TAPS) Combustor, The Roaring 20th Aviation

N i & Ai Q lit S i 2005Noise & Air Quality Symposium, 20054. Dodds, Will, Engine and Aircraft Technologies to Reduce Emissions, UC Technology Transfer

Symposium “Dreams of Flight”, March 1, 20025. McKinney, R.G., Sepulveda, D., Sowa, W. and Cheung, A.K. (2007) The Pratt & Whitney

TALON X l e i i b t : e l ti e lt ith e l ti te h lTALON X low emissions combustor: revolutionary results with evolutionary technology. AIAA 2007-386, The 45th AIAA Aerospace Sciences Meeting, January 2007, Reno, Nevada.

6. Collier, F.S. (2009) Progress toward aviation's environmental goals and objectives – an LTO NOx perspective. ICAO/CAEP Workshop, London, UK, March 30, 2009.

7 Foust M J et al “Development of the GE Aviation Low Emissions TAPS Combustor for7. Foust, M.J, et al., “Development of the GE Aviation Low Emissions TAPS Combustor for Next Generation Aircraft Engines,” AIAA-2012-0936, Nashville, TN, January 9-12, 2012.

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National Aeronautics and Space Administration Low ... · National Aeronautics and Space Administration Low-Emissions Combustors Development and Testing Dr. Clarence T. Chang …

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