Technologies for Turbofan Noise Reduction · with an adequate margin of safety". The phrase "health and welfare" is defined as "complete physical, mental and social well-being and

Technologies for TurbofanNoise Reduction

Dennis HuffNASA Glenn Research Center

Cleveland, OhioU.S.A.

Special thanks to Edmane Envia, James Bridges and Mike Jones

presented at10th AIAA/CEAS Aeroacoustics Conference

Manchester, United KingdomMay 11, 2004

777-200

A330-300

MD-90-30

MD-11

A320-200

747-400

A300-600R

767-300ERA310-300757-200

MD-87MD-82

B-747-300A300B4-620

A310-222

MD-80

B-747-200

B-747-SPDC-10-40

B-747-200

A300

B-747-200

B-747-100

B-737-200B-737-200

B-727-200DC9-10

B-727-100

B-727-100

-20.0

-10.0

0.0

10.0

1960 1970 1980 1990 2000 2010 2020

Year of Certification

Average NoiseLevel Relativeto Stage 3(EPNdB)

HistoryJT3D, JT8D, JT9D,CF6,CFM56

CurrentJT8D-200,PW2000,PW4000,V2500,GE90,PW6000

Future Goals

Stage 2

Stage 3

Stage 4

Advanced Subsonic Technology (AST) Noise Reduction Program Goal of 5 dB

Averagein Service

New Technology Enables AircraftTo Meet Future Requirements

Quiet Aircraft Technology (QAT) Program Goal (additional 5 dB)

Fleet Noise Reduction,

EPNdB

According to a document from the U.S. Environmental Protection Agency (EPA) published in the 1970’s, 55 LDN is the outdoor noise exposure level "requisite to protect the public health and welfare with an adequate margin of safety". The phrase "health and welfare" is defined as "complete physical, mental and social well-being and not merely the absence of disease and infirmity".

0

5

10

15

20

25

30

35

40

45

50

IAD DFW BOS CVG LAX MCO SFO ORD PIT DTW MSP ATL EWR JFK SEA LGA ZRH

Aircraft Fleet Noise Reduction Needed For55 LDN Noise Contours Within Airport Boundaries

Analysis by Don Garber, NASA Langley, using NoiseMap

(PW8000)

Pratt & Whitney’s PW8000 Turbofan Engine(Conceptual)

FanStator

Compressor

Combustor

Turbine

Exhaust

Inlet

Engine Noise Reduction Technologies

Higher Bypass Ratio Swept/Leaned StatorsScarf Inlets

Ac t ive Vane s Ins t a lle d o n t he NASA,Glenn Ac t ive no is e Cont ro l Fan

Roto r Blade

Stator Vane

Active Noise ControlNoise PredictionChevron Nozzles

Forward-Swept Fans

OUTLINE

• Source Diagnostics Tests

• Fan Noise

• Jet Noise

• Static Engine Tests & Flight Validation

• Future Directions

Far-field Acoustics

Flow Diagnostics

Small Hot Jet Acoustic Rig (SHJAR)

Bridges & Wernet (AIAA Paper 2003-3130)Bridges & Wernet (AIAA Paper 2003-3130)

Koch, Bridges, Brown & Khavaran(INCE NOISE-CON 2003)

Koch, Bridges, Brown & Khavaran(INCE NOISE-CON 2003)

• Provide reliable data base for experimental and analytical comparisons• Cover wide range of subsonic and supersonic conditions (Tanna data)

0.5

1.0

1.5

2.0

2.5

3.0

3.50.0 0.5 1.0 1.5 2.0 2.5 3.0

Vjet /C amb

2T2C PIV

PArray

FF acoustics

M=2

M=1

MWE

Ts/Tamb

Jet Noise Baseline Data For CFD/CAA Validation

• Objective: Turbulent flow statistics 0

3

0 1 2Vjet/Camb

U/Uj

V/Uj

TKE/Uj2

v2/u2

L11/Dj

L11/ L12

τ1Uj /Dj

τ2/τ1

Ts/Tamb

Jet Noise Baseline Data For CFD/CAA Validation

Bridges & Wernet (AIAA Paper 2002-2484)Bridges & Wernet (AIAA Paper 2002-2484)

Fan Source Diagnostics Test (SDT)

Rotor & Stator Rotor-Alone

Acoustic Barrier Wall

Top View Schematic of NASA’s 9’ x 15’Low-Speed Wind Tunnel

q ApproachØ Comprehensive Aero-Acoustic Testing

Ø Advanced Diagnostics

Ø Source SeparationØ Inlet vs. exhaustØ stage vs. rotor-alone

Testbed: SDT Fan Rig

Inlet BL Surveys (HW)

Tip Flow Surveys (LDV)

Shock Location Surveys (LDV) Unsteady Pressure Surveys

Wake Surveys (LDV)2-Point Correlation Surveys (HW)

Duct Wall Pressure Surveys Rotating Rake Microphone Surveys

Turbulence Surveys (PIV)

Tested 2 Fans, 3 Outlet Guide Vanes and Rotor-Alone Configurations at Multiple Fan Tip Speeds

Nozzle Exit Surveys (LDV)

Fan Source Diagnostics Test Summary

Traversing Microphone Farfield Surveys

Rotor-Alone Fan Noise

Computation of Rotor Wake Turbulence NoiseNallasamy et. al (AIAA Paper 2002-2489)

LDV Measured Flow Field ResultsPodboy et. al (AIAA Paper 2002-2431)

Vane Unsteady Pressure Results Envia (AIAA Paper 2002-2430)

Wall Measured Circumferential Array Mode ResultsPremo & Joppa (AIAA Paper 2002-2429)

Tone Modal Structure ResultsHeidelberg (AIAA Paper 2002-2428)

Farfield Acoustic ResultsWoodward et. al (AIAA Paper 2002-2427)

Rotor Alone Aerodynamic Performance ResultsHughes et. al (AIAA Paper 2002-2426)

Fan Source Diagnostics Test - References

Power (dB)Mode: (m,n)Power (dB)Mode: (m,n)

Total

(-4,1)

(-4,0)

Cut-On Stator (1xBPF)

114 112

102 98

101 103

100 97

113 111

Cut-Off Stator (2xBPF)

Total

(-10,3)

(-10,2)

(-10,1)

(-10,0)

125 125

120 120

124 124

Exhaust Tone Levels: Prediction Data*Cut-Off Stator

q MethodologyØ Fan Wake Description: Steady RANSØ OGV Acoustic Response: Linearized Euler

Verdon et al. (NASA/CR-2001-210713)Verdon et al. (NASA/CR-2001-210713)

Cut-On Stator

* Data includes a recently discovered 3 dB correction

Fan Tone Noise Prediction (Frequency Domain)

Harmonic content of unsteady pressure (only 9 passages shown)

1xBPF 2xBPF 3xBPF

m =

-10

m =

-10

m =

+12

m =

-42

Cut

-off

Cut

-off

Re (p’)

+

-

Computational Aeroacoustics for Fan Noise Prediction (Time-Domain)

q MethodologyØ Time-Accurate, Non-linear & Inviscid SimulationØ Validated in 2D. Extension to 3D is Underway

Nallasamy et al. (AIAA Paper 2003-3134)Nallasamy et al. (AIAA Paper 2003-3134)

Fan Broadband Noise Prediction

Ø Fan Wake Turbulence Description: Steady RANS

Ø OGV Acoustic Response: Strip-wise lift response (2D cascade)Classical duct acoustics (3D)

Nallasamy et al. (AIAA Paper 2002-2489)Nallasamy et al. (AIAA Paper 2002-2489)q Methodology

Inlet and Exhaust PWL at Approach Condition (Stator Contribution Only)Data includes both coherent and broadband, theory only includes broadband

ü Accounts for realistic geometriesü Uses CFD to achieve higher quality acoustic predictionsü Couples with source codes like LINFLUX or TFaNS

Fan Noise Duct PropagationCDUCT-LaRC Code

Scarf Inlets

Fan Noise Reduction

Ø Low Count Reduces Broadband Noise

Ø Sweep Minimizes BPF Tone Penalty

q Low-Count Swept OGV

blade internal passages

blowing air

q Trailing Edge BlowingØ Fill-In the Rotor Wake

Ø reduces tone noiseØ reduces broadband noise

Woodward et al. (AIAA Paper 2002-2427)Woodward et al. (AIAA Paper 2002-2427)Sutliff et al. (International J. of Aeroacoustics,

Vol. 1, No. 3, 2002)

Sutliff et al. (International J. of Aeroacoustics,Vol. 1, No. 3, 2002)

Virginia Polytechnic Institute Herschel-Quincke (HQ) TubesNASA Advanced Noise Control Fan (ANCF)

Fan Noise Reduction

Ac t ive Vane s Ins ta lle d on t he NASA,Gle nn Ac t ive no is e Cont ro l Fan

Roto r Blade

Stator Vane

NASA/BBN Active Noise Control Fan Test

Fan Noise Reduction

Jet Noise Reduction – Flight Tests

Chevron Benefit Comparison - Perceived Noise Level (PNL)

Model Scale Tests Learjet Flight Data

Model Scale Versus Flight Tests

Brown & Bridges (NASA TM 2003-212732)Brown & Bridges (NASA TM 2003-212732)

B = 22

&

B = 24

V = 28

Scarf Inlet

Active-Passive Liner Fan Blade # Change andLow Number/Cuton FEGV

Advanced PW Fan Case Treatment

Treatment

Treated Primary Nozzle

Pratt & Whitney PW4098 Engine Test

Variable Nozzle Chevron Nozzle Scarf Inlet

Honeywell Flight Demonstrationof Noise Reduction Concepts

1996 Wright Brothers Lectureship in Aeronauticsby Philip M. Condit, The Boeing Company, October 22, 1996

“Ultra-high-bypass-ratio engines [to] reduce fuel consumption,engine maintenance, and community noise. It might be possible to reduce community noise by 10 dB, thus making airplane noise a non-issue at airports.”

Propulsion System•Geared Fan Engines

Aerodynamics•Slotted Cruise Airfoil•Natural Laminar Flow

Flight Systems & Flight Deck•Fly-by-wire

Structure & Materials•Low Temperature Graphite Composite:

•Fuselage•Wing•Empennage

•Cast Aluminum Doors

2016 Subsonic Airplane

Dual-Fan Engine Concept On Blended Wing Body

Backup Charts

0

50

100

150

200

250

300

350

400

1960 1970 1980 1990 2000Year

Nu

mb

er o

f Res

tric

tio

ns

Number of Airports in Database: 591

Noise Restrictions Continue to Grow

Noise AbatementProcedures

Curfews

Charges

Levels

Source: David H. Reed, Manager of Noise Technology, Boeing Commercial Airplane, 1998

Engine Noise Reduction for Large Quad - Sideline Results From P&W Study

88.6

72

94.5

87

96.598.9

84.6

72

93.4

87

94.6

97.5

84.6

72

92.2

87

94.697.0

84.6

81

88

83

80

90.2

84.6

81

86.1

81.579.4

88.8

84.6

81

84.1

7879.35

87.3

65

70

75

80

85

90

95

100

105

Airframe Combustor Fan Exhaust Fan Inlet Jet **Engine Sum

EP

NdB

P&W '92 Tech. BPR=5+Source Red. BPR=5+Source+Nac.ADP Cycle Only ADP+Source ADP+Source+Nac.

Engine Noise Reduction for a Large Quad AircraftResults From Pratt & Whitney Study

Approach Power

Engine Noise Reduction for Large Quad - Approach Results From P&W Study

98.1

76

99100

89

102.7

94.1

76

96.7

99.65

88.75

101.7

94.1

76

94.596.1

88.75

98.9

94.1

83

93 93

73

96.294.1

83

89.7 89.8

73

93.294.1

83

89.5

85.5

73

91.7

65

70

75

80

85

90

95

100

105

Airframe Combustor Fan Exhaust Fan Inlet Jet **Engine Sum

EP

NdB

P&W '92 Tech. BPR=5+Source Red. BPR=5+Source+Nac.ADP Cycle Only ADP+Source ADP+Source+Nac.

Engine Noise Reduction for a Large Quad AircraftResults From Pratt & Whitney Study

Sideline Power

Stage 31992 AST Baseline

1996 UHB Technology ( “Fan 1”)

2000 UHB Technology(“Fan 3”)

Fan Stage Pressure Ratio

Fan Tip Speed (fps)

Ave

rage

EPN

dBR

educ

tion

3

7

4

Evolution of Ultra High Bypass Turbofan Noise ReductionBased On NASA/P&W Advanced Ducted Propulsor Model Tests

Scaled to 130” Diameter Fan, Large Quad Airplane

1220 dB Goal

480 840

1.08 1.28

Increase Bypass Ratio

Improved LowNoise Design

“Fan 1”

“Fan 3”

Takeoff PowerApproach Power

1997 NASA/GE/P&W Separate Flow Nozzle Test

Flow Field Measurements

Jet Noise Reduction Research

Nozzles of the Future

12-Lobe MixerSplitter Nozzle

L L u u2 1 22

120 8 0 7/ . , / .= =

Isotropy:

Anisotropy:

L L u u2 1 22

121 1/ , /= =

MODIFIED “MGB” CODE, now called “MGBK”

Combines CFD solutions with modelingof noise sources to predict far-field acoustics• Small-scale turbulence noise • External mixing noise only• Accounts for both self and shear noise• Non-isotropic turbulence• Can be extended to a 3D geometry(assumes flow is locally axisymmetric)

Jet Noise Prediction

First Integrated Fan Noise Source and Propagation Prediction Code (1994)

Baseline Swept Stators Swept/Leaned Stators

Fan Noise Reduction Research1996 NASA/Allison Swept & Leaned Stator Test

Northrop Grumman HybridActive/Passive Liner Installedin the NASA ADP Fan Rig at theNASA LeRC 9’x15’ Wind Tunnel• Superior Performance Relative to Conventional

Uniform Passive Liners Over Extended Fan Speeds• 3 to 10 dB Attenuation Increase Over Uniform Passive Liners for ADP Fan over the Speed Range of 5200 to 6000 RPM

UniformPassive

Two SegmentPassive

Hybrid Active/Passive

Near Grazing Incidence Fan Noise; Modest Overall Attenuation.

Initial Segment Scatters Modes into Higher Order Radial Modes. Limited Bandwidth ofAttenuation SinceLiner is Efficient onlynear Design RPM.

Initial Active ControlSegment Compensatesfor Changing ParametersResulting from ModeMixture Variations withFan Speed. High Band-width of Attenuation.

Fan Noise Reduction Research1996 NASA/Northrop Grumman Active Noise Control Fan Test

(3-layers) series parallelsingle layer

L

Series elements(3 layers)

Parallel element(single layer)

Combined(series & parallel)

Best Performing Liner Configurations

Stator Vanes (28) 4 ft Fan (16 Blades)

ICD

Rotating Rake mode measurements

inlet & exit plane

Contro l Micropho ne sfore & aft s poo l se c tions (1 6 e ac h row, 9 6 t ot al)

NASA 4 8 " ANC FAN wit h BBN Act ive Vane s

PZT (THUNDER) Act uators 6 pe r vane, 4 Channels of Co ntrol

Fan Noise Reduction Research1998 NASA/BBN Active Noise Control Fan Test

Honeywell TFE731-60 Engine Test

TFE731-60 Engine withInflow Control Device (ICD)

Rotating Microphone

Scarfed Inlet

Chevron Nozzles

Variable Area Nozzle