Engines as Pacemakers for Reduction of Noise and Emission

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DLR, Institut für Antriebstechnik, Abteilung Turbulenzforschung

Engines as Pacemakers for Reduction of Noise and Emission

Wolfgang NeiseDeutsches Zentrum für Luft- und Raumfahrt,

Institut für Antriebstechnik, Abteilung Turbulenzforschung BerlinFocusing Technology

Air Traffic – No.1 in Protecting Environment and ResourcesILA 2004 12th May 2004

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Growth of Worldwide Air Traffic

2000 2010 20201990

100

200

300

400

500

2

4

6

8

10

Source: ICAO / Airbus

5,7% / a

4,9% / a

1012

Pass

enge

r-km

Car

go 1

09t-k

m

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Growth of Worldwide Air Traffic

Number of transport aircraft more than doubled until 2020

30.000

20.000

10.000

2000 2020

13.700

31.800747 and biggerTwin-aisleSingle-aisleSmaller regional jets

Source: Boeing Forecast 2000

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Reduction in Specific Fuel Consumption Due to Aero Engine Design Improvement

0

2

4

6

8

10

12

1950 1960 1970 1980 1990

Comet

707-120 727-100

747-400DC 9-30

A320

737-300

737-200

A300747-200B 767

Year

Liter / 100 Seat km

Quelle: DLR/ERAA

2000

A340-300

A330-300777-200

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0

50

100

150

200

250

300

350

UHC [g/kN] CO [g/kN] NOx [g/kN] max. SN

Dp/

F oo [

g/kN

] bzw

. cha

r. SN JT3D-3B, 1962

JT8D-9, 1965CF6-50C2, 1973JT9D-7Q, 1977PW2037, 1983V2500-A1, 1988Trent 892, 1994

Triebwerkstyp

Emission Reduction Due to Aero Engine Design Improvement

Engine

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Reduction in Aircraft Noise Due to Aero Engine Design Improvement

Year of introduction into service1950 1960 1970 1980 1990 1995

707-100Comet 4

Caravelle

BAC-111

DC9-10

727-100 747-100

737-100

MD80 747-300 A320-100 A321

A340

A330

MD90-30BAC-146-200

737-500737-200

A310-300

L-1011

DC10-10

DC10-30

747-200

DC8-20

DC8-61

CV880-22

A300B2-101

707-300B

767-300

120

110

100

90

Soun

d le

vel,

EPN

dB

• Sideline noise level foraircraft / engine configuration

• Normalized for 100,000 lb thrust

Turbofan 2. generation

Turbojet

777-200

B-52

Turbofan 1. generation

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Noise Footprint at Take-Off

Airbus A 310 (140 t weight)

Boeing B737 (47 t weight)

80 dB(A) Contours

4000 m

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Sound Level and Number of Flights in Frankfurt

0

10

20

30

40

50

60

70

1988 1990 1992 1994 1996 1998 2000Year

300.000

340.000

380.000

420.000

460.000

Num

bero

f Fl

ight

s

Leq

(dB

)

Frankfurt Airport (according to DIN 45543)

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Traffic and NoiseMore than 50% of the German population complain about traffic noise

(Fed. Environmental Agency polls / 2002)

perce

ntage

of pu

pulat

ion

0

20

40

60

100

80

onlin

esta

ndar

d

some/mediumstrongly/extremely

In the EC, 25% of the population (100 Mill. people) suffer from noise

With traffic increasing, noise may bottleneck mobility and economic development

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Noise Footprints

Source: LH

A320 TGV

1000 m 2000 m 3000 m 4000 m

500 m

500 m

0 m

85

85

90

90

94 dB

0 m

85 dB(A)-contour at take-off Noise band at 250 km/h

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Number of Airports With Noise Restrictions(worldwide)

1990 1992 1994 1996 1998 2000

1000

800

600

400

Source: NASA Aero Blueprint 2002

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Schematic of an Aero Engine

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Targets of ACARE “Vision 2020” (Advisory Council for Aeronautics Research in Europe)

Vision Targets (relating to aircraft)• Reduce CO2 by 50%

(20% by engine improvement 25% by airframe improvement,5% by improved operation)

• Reduce NOx by 80%

• Reduce perceived noise by half(equiv. to 10 EPNdB reduction)

• Eliminate noise nuisance outside airport boundaries

• Affordability

Engine contributions to ACARE• Reduce SFC by 20%

increase thermal efficiency(high OPR, high TET)increase propulsive efficiency(high BPR, low FPR)

• Reduce NOx by 80%advanced combustor technology(lean, premixed)

• 6 dB engine noise reduction at each certification point (4 dB by means of aircraft performance and operation practice)

Lower jet speed (high BPR, low FPR)

• Affordability

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Fuel Burn Reduction Potential

Quelle: IEA 2002

Personentransport in OECD-Regionen

- Technology -

Source: IPCC

Present

Future

60%40%

40%60%

Power plant

Airframe

100 %

1960 today 2010* 2020*

-15 bis -20% -30 bis -50%

- 70%

* Technology available

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Conventional Combustor (AFRtotal ≈ 40)

17% air35% air 40% air

8% air

Rich primaryzone

T3 800Kp3 35barT4 1700K

Future combustor requirements50% reduction in NOx Increased turbine temperature

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Development Trends for Low Emission Combustors

Conventional single annular combustor; burners with diffusion flames

Axially staged combustor; conventional burners with diffusion flames

Axially staged combustor; lean burners in main stage

Singe annular combustor; lean burners and internal pilot flames

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Future Combustor (AFRtotal ≈ 35)

Technology Goals:Lean combustion with wide operating rangeImproved cooling concepts

T3 880Kp3 50barT4 2000K

75% air 20% air5%air

Lean primaryzone

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Sound Sources on Transport Aircraft

Jet Fan

Landing gears

Flaps

SlatsEnginesHigh lift deveices

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Noise Sources in Aero Enginesof Transport Aircraft

Fan• Tones at various

frequencies• Broadband noise• „Buzz saw“-noise

Compressor• High frequency tones• Broadband noise

Combustor• Low frequency broadband noise

Turbine• High frequency tones• High frequency broadband

noise

Jet• Broadband

noise

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Jet Noise

Noise source external to engine.

Limited noise reductions achievable by► forced mixers for core and bypass flows► serrated nozzles (chevron nozzles),

2-4 dB reduction potential

Retrofit to existing engines possible

Substantial noise reductions only by► reducing jet speed► requires new ultra-high bypass ratio engines

.

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DLR/Lufthansa Chevron Nozzle (Tested on A319, 2001)

CFM56-5A5: Frequency-dependent noise reduction 0 – 2 dB

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Langsam laufender Getriebe-Fan - Nebenstromverhältnis ≥ 12 -Noise Reduction Technologies for Aero Engines

(EU FP5 Technology Platform SILENCE(R))

Design features of “Advanced Environmentally Friendly Engines”

Low noise fan and LP compressor Low emission combustor, Low noise LP turbine Low noise cycle (jet).

Low noise exhaust designs:Fan nozzle lip treatmentCore nozzle lip treatmentHigh frequency hot stream linerLow frequency hot stream liner

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Langsam laufender Getriebe-Fan - Nebenstromverhältnis ≥ 12 -Noise Reduction Technologies for Aero Engines

(EU FP5 Technology Platform SILENCE(R))

Low Noise Nacelle Concepts:

Novel inlet and fan duct passive liners Negatively scarfed inlet Treated inlet lip Treated fan duct splitter

Active Systems:

Inlet buzz-saw wall mounted systems Engine adaptive/active liners Active stator

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Langsam laufender Getriebe-Fan - Nebenstromverhältnis ≥ 12 -Low-Speed Geared Fan (BPR ≥ 12)

Average relative flow Mach number at blade tipsToday´s fans (BPR ~ 6): Marel ≈ 1,5 Geared fan (BPR ≥ 12): Marel < 1,0

Noise benefits• Strongly reduced jet noise due to lower jet speed

No buzz saw noiseReduced rotor-alone and rotor-stator-interaction noiseLow rotor blade number may allow cut-off design for BPF plus 2*BPFLow cabin noiseSteep take off possible (high altitudes shortly after take-off)

Demonstration with a model fan in EU Techn. Platform SILENCE(R)Design and acoustic testing by DLRResults for noise reduction potential available in 2004/2005

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DLR-Design for SILENCE(R) Geared UHBR-Fan

• BPR = 12 • Subsonic relative

inflow at take-off conditions

• 3D rotor blade design

• High specific flowto limit fan diameter

• Reduced fuelconsumption due to higher bypass ratio

• Higher propulsiveefficiency

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Active Noise Control for Aero-Engines

Experimental Rig at DLR Cologne

Loudspeakers / microphones

Sound

Anti-Sound

Principle

DLR-ATAG Turbo Turbotech II: Partners: DLR, EADS, MTU

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ANC: Frequency Spectra in Inlet Duct

Rotor-coherent spectrum (average over 62 microphone positions)

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Active Noise Control for Axial-Flow Machines by Blade Tip Flow Control (DFG Sfb 557: TP B4)

Goals

Replace conventional loudspeakers by light-weight aeroacoustic anti-sources

aeroacoustic sources are generated in the rotor plane by „disturbing“ the flow around the blade tips

Additional blade forces are set up that act as anti-sources and generate the required secondary sound field

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Generation of Aeroacoustic Sound SourcesAir Injection Using Wall Flush Mounted Nozzles

Different orifice shapes:

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Control of Higher-Order Mode Sound Field With Steady Air Injection

Steady air jetsZ/V = 18/16, 16 nozzles, n = 3000/min

0 1000 2000 3000 4000 500050

60

70

80

90

100

110

120

20.6

dB

MJets/MFan = 0.9% cµ = 0.0015

BPF

Outlet

Control off Control on

L W [d

B]

Frequency [Hz]

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Future Concept EngineQuiet, Efficient, Low Emission

Heat exchangerLow pressureturbine

High pressureturbine

Radial compressor

Axial compressor

Low noise fan Gear IntercoolerLow emission combustor

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Summary

Major improvements in reducing aircraft noise and emissions have been made over the last 50 years.Further efforts are necessary to reach the goals set by the ACARE „Vision 2020“ Reduction potentials available are sufficientAdequate research funding mandatoryLargest noise reduction potential for engine noise seen in UHBR engines to reduce jet noise down to an acceptable levelOther noise sources of aero engines need also to be reduced to meet the 10 dB reduction goalActive noise control concepts promising for tone noise reductionTo help solve the aircraft noise problem in the short run, development and validation of retrofit noise reduction methods also required

Documents

Engines as Pacemakers for Reduction of Noise and Emission