NASA Environmental Workshop

John G. Meier

Vinod Nangia

August 12, 1999

21-10790

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V9485-2

Environmental Impact of Small Engines Becoming Critical• Turbofans for Regional and Business Aviation, APUs have significant

environmental impact

– Frequent takeoffs and landings

– Widespread access to airports

– APU ground operation

• Strong projected market growth, increased use

– Growth in air travel

– Transition from turboprop to turbofan (Regional)

– Fractional ownership

• Greatest technology challenges

– Size effects

– Thermodynamic cycle trends

– ETOPS requirements for APUs

Technologies for noise and emission reduction in small turbine engines are unique

B

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Regional and Business Jets and APUs Under New Environmental Scrutiny

• Regional and Business Aviation aircraft operate from airports in >3,500 U.S. communities

Small engine environmental impact is the same as large engines

Commercial Transports

Business Aviation

0

3

6

9

12

15

0 3 6 9 12 15Engine Pressure Ratio

NO

x E

mis

sio

n I

nd

ex (

GM

/KG

M F

uel

)

Equivalent ‘96 ICAO

• Ground operation of APUs creates NOx emission above the equivalent ‘96 ICAO levels

• Regional & General Aviation Account for 40% of All Takeoffs & Landings

B

0

5

10

15

20

25

30

35

40

1991 1993 1995 1997 1999 2001 2003 2005 2007

Historical Forecast

Calendar Year

Ta

keo

ffs

& L

an

din

gs

, M

illi

on

s

Commercial Transport

Military

Regional

General Aviation

Source: FAA Air Traffic Activity

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Regional Jet Fleet Market Growth

• Turbofans replacing turboprops for customer comfort and safety

– Higher Pressure Ratios and Thrust ( emissions)

– Thrust and Fleet size ( Noise)

Turbofan market growth drives increased noise and emissions

U.S. Regional Fleet ForecastAircraft (Units)

2,000

1,800

1,600

1,400

1,200

1,000

800

600

400

200

01987 1992 1997 2002 2007

Year

Historic Forecast

Turbofans

B

Turboprops

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Fractional Ownership Game Changes Business Jet Market • Smaller companies flying to

smaller airports - more takeoffs and landings

• U.S.-based business aviation accounts for 75% of the overall market

Fractional ownership dramatically increases takeoffs and landings

PilatusIAI

Gulfstream(USA)

Learjet(USA)

Dassault

1998 Sales of New Turbine-Powered Aircraftto Business Aircraft Operators by Manufacturer

Boeing(USA) Socata/

Aerospatiale

Raytheon(USA)

Canadair

Cessna(USA)

C

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Auxiliary Power Unit Dependence Increasing

• Future aircraft standard for twin engine use requires APUs

– Extended Twin Engine Operations (ETOPS)

– APU use in engine-out situation

– Increased operating altitudes required

• Lack of facilities at small airports require APU usage for Regional and Business Jets

Increased use of APUs is an added source for noise and emissionsC

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Local Airports Driving Environmental Standards for Turbofans and APUs

*

Stockholm

*

*

Denmark

Zurich

Federal regulation will evolve from local restrictions

Proprietary

1996 ICAO

Class VClass VI

• Aircraft landing fees based on emissions and noise

• APU operating time, restrictions underway

A

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Regional Jets, Business Aviation, and APUs Face Unique Design Challenges

• Size Effects:

– Higher % cooling air

– Tolerance stacks

– No space for multi-dome concepts

• APUs - large ignition and blowout range

– Cold soak engine to sub-zero temperatures

– High-altitude start

Relative size comparison of Boeing 777 Combustors

APU 14 FuelNozzle Tips

Main Engine60 Fuel Nozzle Tips

Not the actual combustor

Physical size forces novel solutions for emissions and noiseB

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Technology Directions

Improved operability and low emissions needed for compact combustor

Fuel Staging Technology

Individual AtomizerControl and Spray

Advanced FlameStabilization

Single-dome, staged

Alt

itu

de

Flight Speed

IgnitionEnvelope

ETOPS

Single-dome, not staged

A

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V9485-10

Smaller Aircraft Face Stricter Noise Rules

Noise abatement technology is critical to smaller engines

70

80

90

100

Approach Takeoff Sideline

EP

NL

Stage 3

Transport (Airbus 319)Business Jet (Falcon 2000)

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V9485-11

100

110

120

130

140

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

APU Year of Introduction Into Service

To

tal

No

ise

(In

let

and

Ex

ha

us

t)P

WL

re:

10

^(-

12)

Wat

ts [

dB

]

10dB

APU Core Technology

Commercial APU Data Trend Future Goals, Anticipated Requirements

European Markets Push For Low APU Noise

• Current APU Operations being restricted due to noise

• Aircraft Manufacturers demand 5-10 dB noise reduction

• APU noise reduction research must intensify to support market needs

Airport workers and community residents REQUIRE lower ramp noise

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Technology Directions

A system approach is needed to globally reduce engine noise

Advanced Fan Designs

Advanced Nozzle Designs

Advanced Suppression

Measurement Technology

Variable Engine Cycle

A