Post on 06-Jul-2020
transcript
www.nasa.gov
Aircra&'Engine'Noise'Research'and'Tes3ng'at'the'NASA'Glenn'Research'Center'
Dave'Ellio;'NASA'Glenn'Research'Center,'Acous3cs'Branch'David.M.Ellio;@nasa.gov'
March'25,'2015'
https://ntrs.nasa.gov/search.jsp?R=20160014700 2020-07-31T07:20:36+00:00Z
www.nasa.gov
NASA'Glenn'Research'Center'
• 1941'IAircra&'Engine'Research'Laboratory'under'Na3onal'Advisory'Commi;ee'for'Aeronau3cs'(NACA)'
• 1958'I''Renamed'Lewis'Research'Center'and'incorporated'into'NASA'
• 1999'–'Renamed'John'H.'Glenn'Research'Center'• Center'of'Excellence'in'Turbomachinery'• Diversified'into'certain'areas'of'space'research/
management'e.g.'microgravity,'electric'propulsion,'space'power'and'communica3ons'
• Main'facility'adjacent'to'Cleveland'Hopkins'Interna3onal'Airport,'second'facility'Plum'Brook'near'Sandusky'
www.nasa.gov
Glenn Core Work Areas
3
www.nasa.gov
Acous3cs'Branch'within'NASA'Glenn'Organiza3on'
4
Office of the Director (A) Director
Deputy Director (A) Associate Director (A) James M. Free
Dr. Janet L. Kavandi Janet L. Watkins
NASA Safety Center (N)
Alan H. Phillips
Office of the Chief Financial Officer (B)
Laurence A. Sivic
Office of the Chief Counsel (G)
J. William Sikora
Plum Brook Station (H)
David L. Stringer
Office of Diversity and Equal Opportunity (E)
Lynda D. Glover
Facilities, Test and Manufacturing Directorate (F)
Thomas W. Hartline
Aeronautics Directorate (K)
Therese M. Griebel
`
Office of the Chief Information Officer (V)
Sean M. Gallagher
Center Operations Directorate (C)
Robyn N. Gordon
Office of Technology Incubation and Innovation (T)
Dr. John M. Sankovic
Research and Engineering
Directorate (L)
Dr. Rickey J. Shyne
Space Flight Systems
Directorate (M)
Bryan K. Smith
Safety and Mission Assurance
Directorate (Q)
Anita D. Liang
Office of Human Capital Management (J)
Lori O. Pietravoia
Associate Director for Strategy (A)
Dr. Howard D. Ross
PS–01242–0414 ver. 03 /13/ 2015
www.nasa.gov
For more information on Glenn’s Organizational Structure please visit: http://www.grc.nasa.gov/WWW/OHR/Orglist/
Glenn Research Center at Lewis Field
Encl
osur
e 1
Research and Engineering Directorate (L)
Communications and Intelligent
Systems Division (LC)
Power Division (LE)Materials and
Structures Division (LM)
Systems Engineering and
Architecture Division (LS)
Propulsion Division (LT)
Management Support and
Integration Office (LB)
Chief Engineer Office (LA)
Research and Engineering Directorate
www.nasa.gov
For more information on Glenn’s Organizational Structure please visit: http://www.grc.nasa.gov/WWW/OHR/Orglist/
Glenn Research Center at Lewis Field 6
Propulsion Division (LT)
Turbomachinery and Turboelectric Systems
Branch (LTE)
Inlets and Nozzles Branch(LTN)
Icing Branch (LTI)
Acoustics Branch (LTV) Electric Propulsion Systems Branch (LTS)
Propulsion Systems Analysis Branch (LTA)
Chemical and Thermal Propulsion Systems
Branch (LTR)
Combustion Physics and Reacting Systems Branch
(LTX)
Engine Combustion Branch (LTC)
Fluid Physics and Transport Processes
Branch (LTZ)
Thermal Systems Branch (LTT)
Fluid and Cryogenic Systems Branch (LTF)
Encl
osur
e 2Propulsion*Division*
www.nasa.gov
NASA'Aeronau3cs'Programs'
• Most'acous3c'research/tes3ng'done'under'NASA'agency'programs/projects'with'milestones'
• Some'Example'Programs/Projects'– Previous'
• Late'1990’s/Early'2000’s'I''Advanced'Subsonic'Technology'(AST)'and'Quiet'Aircra&'Technology'(QAT)'
– Recent'• Fundamental'Aeronau3cs'Program'I'Subsonic'Fixed'Wing'Project'–'longer'
range'technology'• Environmentally'Responsible'Avia3on'Program'–near'term'technology'• Advanced'Air'Vehicles'Program'–'Advanced'Air'Transport'Technology'I'present''h;p://www.aeronau3cs.nasa.gov/programs.htm'
www.nasa.gov
* Projected benefits once technologies are matured and implemented by industry. Benefits vary by vehicle size. N+1 and N+3 values are referenced to a 737-800 with CFM56-7B engines; N+2 values are referenced to a 777-200 with GE90 engines.
** ERA’s time-phased approach includes advancing “long-pole” technologies to TRL 6 by 2015. *** CO2 emission benefits depend on life-cycle CO2e per MJ for fuel and/or energy source used.
! To reduce the impact of aviation on the environment, NASA has adopted a set of aggressive noise, emissions, and fuel burn goals for future subsonic transport aircraft.
! The environmental goals are traceable to the U.S. National Aeronautics Research and Development Plan.
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U.S. Subsonic Transport Noise Goals'
8'
www.nasa.gov
777-200
A330-300
MD-90-30
MD-11
A320-214 747-400
A300-600R
767-300ER
757-200
MD-87 MD-82
B-747-300
A300B4-620
A310-222
MD-80
B-747-200
B-747-SP DC-10-40
B-747-200
A300
B-747-200
B-747-100
B-737-200 B-737-200
B-727-200
DC9-10
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 Noise Level
Relative to
Chapter 3 (EPNdB)
Chapter 2
Chapter 3
Chapter 4
B-737-300 B-737-800
B-737-900 A320-232
B-777-300
A340-541
A318-112
DC8-20
B-707-100
B-787
B-747-8F A380-841
B-737-900ER
A330-243
Chapter 14
1992 Small Twin Ave. Production
AST TRL 6 Goal
QAT TRL 4 Goal
N+1 TRL 4-6 Goal
N+2 TRL 4-6 Goal
1997 Small Twin Baseline
Subsonic Aircraft Noise Levels & Research Goals
9'
www.nasa.gov
Acoustics Branch Research Focus
Conduct'research'for'reduc3on'of'aircra&'propulsion'system'noise''
• Focus'on'engine'noise&reduc+on&technologies'that'maintain'acceptable'aerodynamic'performance'for'both'subsonic'and'supersonic'applica3ons.'
• Perform'diagnos+c'experimental'and'analy3cal'studies'to'understand'underlying'fundamental'physics'of'noise'genera3on'and'mi3ga3on.'
• Engine'noise'predic+on&codes'are'developed'and'validated'using'experimental'data'ranging'from'empirical'to'Computa3onal'Aeroacous3cs'(CAA)'tools'that'directly'compute'the'noise'genera3on'and'propaga3on.'
• Maintain'worldIclass'experimental'capability'in'the'9x15'Low'Speed'Wind'Tunnel,'AeroIAcous3c'Propulsion'Lab,'and'the'Acous3cal'Tes3ng'Lab.'Use'capability'for'concept'valida3on,'to'generate'benchmark'databases'for'code'development,'and'available'for'reimbursable'use.'
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Cross'Sec3onal'Drawing'of'Turbofan'Model'used'in'Wind'Tunnel'Tes3ng'
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LTV/ Acoustics Branch '
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Noise Diagnostics • Concept Investigation
• Engine Noise Source Identification
Noise Prediction • Model Development
• Simulations
Noise Reduction • Concept Development
• Testing & Evaluation
GTF Fan
Honeywell Engine Test
Fan Noise Prediction
Jet Flow & Noise Simulation
Jet Flow PIV Data
Jet Flow Prediction
Swept Stator for Fan Noise Reduction
Nozzle Chevrons for Jet Noise Reduction Trailing Edge Blowing for Fan Noise Reduction
Jet Flow Turbulence via PIV
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Noise'Reduc3on'
Over-the-Rotor metal foam acoustic treatment fan case
Acoustically treated soft vanes Propulsor
Exhaust Systems
Actuator'Off'
M'1.3'Jet'
Actuator'On'
Active control of jet
Model hardware
Passive 3-D nozzle concepts
Source Noise, Attenuation, Cancellation
www.nasa.gov 14'
Diagnos3cs'
In a cooperative effort with NAVAIR, phased array measurements were obtained for an F404 engine with a modified nozzle that included chevrons
Tip vortex
Particle Image Velocimetry (PIV)
CMFI Pylon
Array Peak Level
No Pylon
Array Peak Level
Flush Kevlar Acoustic Cover
Pressure Sensitive Paint
Phased Arrays, PSP, PIV, HW/HF, Rotating Rake, FF Microphone
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Predic3on'
FEGV Wake Interaction, RANS Based
Empirical (ANOPP), RANS Based, Non-Linear High Order
Open Rotor RANS
Strouhal Number
Pola
r Ang
le fr
om In
let (
°)
TCON C0 Z1
10-1 100
60
80
100
120
140
160
Strouhal Number
Pola
r Ang
le fr
om In
let (
°)
TCON C0 Z4
10-1 100
60
80
100
120
140
160
Strouhal Number
Pola
r Ang
le fr
om In
let (
°)
TCON C0 Z9
10-1 100
60
80
100
120
140
160
Strouhal NumberPo
lar A
ngle
from
Inle
t ( °
)
TCON C90 Z1
10-1 100
60
80
100
120
140
160
Strouhal Number
Pola
r Ang
le fr
om In
let (
°)
TCON C90 Z4
10-1 100
60
80
100
120
140
160
Strouhal Number
Pola
r Ang
le fr
om In
let (
°)
TCON C90 Z9
10-1 100
60
80
100
120
140
160
Model ΔSPL: Ma = 1.329, Tsr = 1.76, Mfj = 0.1
-3
-2
-1
0
1
2
3
Strouhal Number
Pola
r Ang
le fr
om In
let (
°)
TCON C0 Z1
10-1 100
60
80
100
120
140
160
Strouhal Number
Pola
r Ang
le fr
om In
let (
°)
TCON C0 Z4
10-1 100
60
80
100
120
140
160
Strouhal Number
Pola
r Ang
le fr
om In
let (
°)
TCON C0 Z9
10-1 100
60
80
100
120
140
160
Strouhal Number
Pola
r Ang
le fr
om In
let (
°)
TCON C90 Z1
10-1 100
60
80
100
120
140
160
Strouhal Number
Pola
r Ang
le fr
om In
let (
°)
TCON C90 Z4
10-1 100
60
80
100
120
140
160
Strouhal Number
Pola
r Ang
le fr
om In
let (
°)
TCON C90 Z9
10-1 100
60
80
100
120
140
160
ΔSPL: Ma = 1.33, Tsr = 1.76, Mfj = 0.25
-3
-2
-1
0
1
2
3
Twin Jet Effect: Sample, ΔSPL dPSD = (PSD Modeled) – (PSD Measured) Fine Turbo, Open Rotor RANS
Broadband Aeroacoustic Stator Simulation (BASS) Code, ANCF simulation, high order, high accuracy
www.nasa.gov
Distribu3on'by'Technical'Focus''
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Facili+es&and&Advanced&Tes+ng&Techniques&for&
Database&Genera+on&and&Concept&Evalua+on&for&
Exhaust&Systems,&Fan&Systems,&Open&Rotors,&and&
small&engines.&
Aero-acoustic Propulsion Lab
Acoustical Testing Lab (ATL)
9x15/8x6 Wind Tunnel
Small Hot Jet Acoustic Rig (SHJAR)
Advanced Noise Control Fan
(ANCF)
Nozzle Acoustic Test Rig (NATR)
17'
L
CW-17 Free Jet Facility
www.nasa.gov
Advanced'Noise'Control'Fan'Design,'test,'and'evalua3on'for'technical'riskImi3ga3on'of'most'of'the'innova3ve'fan'noise'reduc3on'technologies'developed'by'NASA'over'the'past'20'years.''
1992&–&2014&:&&LowNTRL&research&performed&on&ANCF&enabled&the&advancement&of&
mul+ple&noise&reduc+on&and&measurement&technologies.&
Inves&ga&ng)transferring)the)ANCF)to)a)university)to)jointly)operate)the)ANCF)to)maintain)research)capability,)and)provide)relevant)STEM)opportuni&es,)in)the)area)of)fan)acous&cs.))
Highly'flexible,'fundamental'test'bed.''Mul3ple'configura3ons,'including'rotor'alone.'4Ifoot'diameter'ducted'fan'Low'speed:'(variable)'''''~1800'rpm,'V3p'~375'&/sec,'Mduct'~'0.15'
Used'to'provide'aeroIacous3c'database'and'to'evaluate'noise'reduc3on'technologies'
Data'acquired'by'externally'clocking'data'system'from'rig'tachometer'signal'
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The'ANCF'has'been'used'in'over'6'internal,'8'external'programs'(2'reimbursable),'2'NRAs,'3'SBIRs,'and'2'Aero'Acous3c'Research'Consor3um'programs.'These'were'integrated'in'GRC’s'noise'reduc3on'program'milestones.'It'is'the'only'complete'aeroIacous3c'data/geometry'set'publically'available. 'Over'100'papers'wri;en'based'on'ANCF'data.'(~4'I6'per'AIAA'AeroIAcous3cs'Conference)'
www.nasa.gov
DGEN380&Turbofan&Engine'
The'DGEN'engine'is'the'world’s'smallest'turbofan:'it'is'intended'for'4I5'seat'twinIengine'Personal'Light'Jets'flying'under'25,000&'and'250kts.'The'DGEN'
engine'is'manufactured'by'Price'Induc3on.'
14”'
52”'
The'characteris3cs'of'the'DGEN380'enable'it'to'be'an'excellent'representa3on'of'modern'turbofan'engines.'
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www.nasa.gov
Aircra&'Engine'Noise'Sources''
• Fan'noise'– Consists'of'broadband'and'tonal'– Broadband'primarily'random'and'generated'by'rotor'alone''– Tonal'(Blade'Passage'Frequency'and'harmonics)'generated'by'
rotor'wakes'impinging'on'stator'vanes,'correlated'to'sha&'orders'or'engine'RPM'
• Jet'noise'– Due'to'mixing'of'high'temperature'high'velocity'streams'with'
lower'velocity'lower'temperature'streams'• Core'noise'
– Produced'by'the'combus3on'process,'compressor'and'turbine'noise'
www.nasa.gov
Experimental'Fan'Noise'Tes3ng'
• 9x15'Low'Speed'Wind'Tunnel'Facility'• Models''
– Turbofan'– Counter'Rota3ng'Open'Rotor'
• Data'Acquisi3on'• Data'Analysis'• Noise'Reduc3on'Technologies'
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www.nasa.gov
Power&Spectrum&Density&from&0&to&5&kHz&of&the&Counter&Rota+ng&Open&Rotor&Historical&Baseline&
Blades&at&6450&corrected&RPM&with&takeoff&pitch&angle&and&141°rees&rela+ve&to&the&rear&rotor&&
pitch&change&axis.&Blade&Passage&and&Interac+on&Tones&are&labeled.''
www.nasa.gov
9x15'LSWT'acous3c'measurement'techniques'Objec3ve:'Examine'acous3c'measurement'techniques'to'improve'data'accuracy/increase'acquisi3on'efficiency.'
Techniques'tested:'• Linear'Microphone'Array'• Mul3Imicrophone'traversing'probe'• Con3nuous'Traversing'Microphone'
Approach:''• Design'and'test'techniques'and'compare'with'
present'acquisi3on'methods'
Results/Conclusions'• Linear'array'compares'well'with'standard'traversing'
microphone'over'compressed'frequency'range'
• 3'headed'microphone'had'low'background'noise'level'rela3ve'to'single'mic'stand'while'allowing'two'addi3onal'azimuthal'angle'measurements'
• Con3nuous'traverse'has'shown'excellent'comparison'with'discrete'traverse'and'has'ability'to'save'3me'
Frequency, Hz
PSD,dB
0 2000 4000 6000 8000 10000
Auto Spectra of Traversing Microphone vs Linear Array Cross Spectra at 90 degreesrelative to Rear Rotor Pitch Axis for Historical Baseline at 100% Design Speed, M=0.26 dB Plate Correction included for Linear Array
!
27
Linear'Array' 3'Mic'Traverse'
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Acous3c'Data'Acquisi3on'
• Bruel'&'Kjaer''I ¼”'Microphones'with'nosecones'I Nexus'Signal'Condi3oning'Units'
• RC'Electronics'Datamax'for'acquisi3on'using'200'kHz'sample'rate'• One'traversing'microphone'for'capturing'model'direc3vity'
I Previously'fixed'stop'I Recently'converted'to'con3nuous'sweep'
I More'direc3vity'resolu3on'I Time'Savings'
• Fixed'Microphones'• Model'3ming'signals'(once'per'rev)'and'traverse'posi3on'recorded'• Facility'system'records'tunnel'ambient'and'model'condi3ons'
• Pressure,'Temp,'Humidity,'Mach'No.'• RPM,'Angle'of'A;ack'
'
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www.nasa.gov
deciBels'
30
!!!" = 20 ∗ !"#!"(!!!"#
)!
!!!" = 10 ∗ !"#!"!!!"#
!!
!!!"# = 2.0!10!!!
www.nasa.gov
Acous3c'Data'Analysis'• Data'taken'is'model'scale'–'frequency'scales'inversely'• Fast'Fourier'Transform''I'3me'to'frequency'domain'• Correc3ons'included'for'microphone'and'nosecone'calibra3ons'• 1'foot'lossless'–'results'o&en'projected'to'one'foot'distance'with'
atmospheric'a;enua3on'removed,'enables'comparison'of'data'taken'at'different'distances'
• Usually'in'Power'Spectral'Density'(dB/Hz)'I'allows'direct'comparison'of'data'taken'at'different'sampling'frequencies,'different'bandwidths'
• Overall'Sound'Pressure'Level'(OASPL)'–'Used'to'give'a'total'value'for'each'direc3vity'angle'measured'
• Overall'Sound'Power'Level'(OAPWL)'–'Gives'a'single'value'for'the'acous3c'power'by'integra3ng'OASPL'for'each'angle'over'the'en3re'direc3vity'surface'
• Effec3ve'Perceived'Noise'Level'(EPNL)'–'Common'NASA'and'industry'calcula3on'to'give'single'value'for'an'aircra&'condi3on'(e.g.'takeoff),''weights'frequency'bands'and'includes'a'3me'element'simula3ng'aircra&'flyover,'data'is'full'scale'and'usually'u3lizes'an'aircra&'configura3on'(medium'twin'engine'etc.)'
www.nasa.gov
Major'Challenge:'Reducing'noise'without'adversely'affec3ng'engine'
performance'or'efficiency''
www.nasa.gov
• Cycle'Change'I'Higher'Bypass'Ra3o'– Increase'amount'of'weight'flow'through'the'bypass'duct'while'reducing'flow'
through'core'engine'– Results'in'larger'fan'diameter'– Larger'fan'has'lower'3p'speed'while'maintaining'thrust'(noise'is'a'func3on'of'fan'
3p'speed,'supersonic'3p'speed'produces'Mul3ple'Pure'Tones'due'to'shock'noise)'– Lower'fan'loading'and'3p'speed'should'reduce'noise'– A&'fan'dominant'noise'signature'
• Rotor/Stator''– Increased'spacing'–'reduces'wake'impact'on'stators'– Swept'Stators'–'larger'distance'between'rotor'and'stator'at'3p,'reduces'3p'vortex'
on'stators'– Leaned'Stators'–'Orients'stators'more'in'line'with'swirl,'wake'angle'of'impact'less'
severe'
Fan'Noise'Reduc3on'Technologies'
Radial'Stators' Swept'Stators'
www.nasa.gov
Fan'Noise'Reduc3on'Technologies'(Cont.)'
• Acous3c'Liners/Treatments'– Usually'used'on'inner'duct'of'nacelle,'also'inner'hub'loca3ons'– Other'loca3ons'inves3gated'such'as'a&'spli;er'– Over'the'Rotor'Treatment'– So&/Treated'Stator'Vanes'
• Fan'Trailing'Edge'Blowing'– Fills'in'wakes'produced'by'blades'lowering'fan'stator'interac3on'
34
www.nasa.gov
NASA/P&W'Fan'1'Liner'and'Fan'2'Test'Objec3ve:''
• Acous3c'performance'of'various'liner'designs'• Validate'noise'dependence'on'3p'speed'• Determine'noise'of'advanced'casing'treatment'
used'to'increase'stall'margin'Approach:'
• Test'combina3ons'of'bulk,'SDOF,'DDOF'liners'in'inlet,'mid,'and'a&'loca3ons'of'Pra;'ADP'Fan'1'
• Test'lower'3p'speed'Fan'2'while'keeping'pressure'ra3o'as'Fan'1'
Results:'• Full'DDOF'liner'set'showed'addi3onal'noise'
a;enua3on'compared'to'very'effec3ve'1995'Baseline'liner'
• Fan'2'showed'limit'of'reduced'3p'speed/higher'loading'due'to'increase'in'noise'rela3ve'to'Fan'1'
• Advanced'casing'treatment'showed'no'acous3c'penalty'while'increasing'stall'margin'
• Develop'acous3c''''''database'for'ultraIhigh'''''bypass'ra3o'turbofan''''''model'
35
!
Max'Flow'Advanced'Casing'Treatment'
ADP'Liner'Loca3ons'
www.nasa.gov
A&'Duct'Treated'Spli;er'Objec3ve:''
• Reduce'a&'fan'noise'• Keep'performance'losses'to'minimum'
Approach:'• Design'and'test'a&'acous3cally'treated'
spli;er'on'Pra;'ADP'model'in'9x15'LSWT'Results:'
• Trailing'edge'of'spli;er'must'be'kept'thin'to'eliminate'Strouhal'shedding'tones'
• Spli;er'tuned'to'17'kHz'model'scale'to'a;enuate'highest'annoyance'noise'
• Spli;er'did'not'show'expected'noise'reduc3on'possibly'due'to'tunnel'background'noise'or'moun3ng'method'
• Sta3c'test'did'show'spli;er'provided'a;enua3on'at'design'frequency'
• Performance'loss'kept'to'1%'of'thrust'and'was'primarily'due'to'skin'fric3on'
• Added'technology'such'as'microIblowing'could'reduce'skin'fric3on'
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Black - Hard wall Nacelle Red - Treated Nacelle (DDOF) Blue - Treated Nacelle with Treated Splitter '
ADP Takeoff - 136 degrees '
A&''Spli;er'
kHz'
SPL,'dB'
www.nasa.gov
Over'the'Rotor'–'So&'Vane'Concepts'Objec3ve:'• Use'treatment'over'the'rotor'to'reduce'
rotor'alone'noise'• Reduce'rotor/stator'noise'at'source'
using'so&'vanes'
Conclusions'• OTR'treatment'not'effec3ve'in'reducing'noise'
unlike'other'previous'tests'had'shown'• So&'Vanes'showed'PWL'reduc3ons'on'the'
order'of'1'dB'rela3ve'to'hard'vanes'for'certain'sha&'speeds'
Over'the'Rotor'Treatment' So&'Vanes'
Approach:'• Design'and'Test'concepts'on'turbofan'''''''model'in'9x15'LSWT'
37
www.nasa.gov
Fan'Trailing'Edge'Blowing'
Objec3ve:'Characterize'aero/acous3c'performance'of'Fan'Trailing'Edge'Blowing'at'moderate'TRL''Approach:'Design'and'test'representa3ve'fans'in'low'speed'test'rig'and'the'9x15'LSWT''Outcome:''• Tones'and'broadband'impacted'by'TEB;'
@'takeoff'II'2BPF,'I5dB;'3BPF,'I1dB;'4BPF'+.5'dB''
• Thrust'slightly'higher'for'TEB'(9x15)'• TEB'efficiency'94.4%'vs.'95.6%''baseline'
(9x15)'• 2%'blowing'rate'op3mum,'about'2db'
OASPL'noise'reduc3on'rela3ve'to'baseline'across'spectrum'
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OAS
PL,'dB'
%'speed'Fite,'Woodward,'Envia,'Sutliff,'Podboy,'Jeracki,'Heidelberg,'John'Gazzaniga'
www.nasa.gov
Open'Rotor'Test'Entry'
Objec3ve:'Reduce'counter'rota3ng'open'rotor'noise'using'advanced'blade'designs'Approach:'Test'blade'design'concepts'in'9x15'LSWT'on'open'rotor'drive'rig'Outcome:''• Test'of'Baseline'and'mul3ple'advanced'
blade'sets'• Angle'of'A;ack'effects'• Pylon'wake'noise'characteriza3on'• Data'used'for'system'studies'of'aircra&'
noise'comparison'versus'ducted'engines'• Obtained'large'database'of'open'rotor'
blade'acous3cs'for'pitch'angle,'angle'of'a;ack,'pylon'wake'
39
www.nasa.gov
Rotor'Alone'Nacelle'System'Objec&ve(• Iden3fy'and'characterize'isolated'rotor'noise'sources'Approach(• Develop'propulsor'simulator'that'eliminates'internal'
structures'and'isolates'rotor'within'nacelle'while'maintaining'opera3ng'characteris3cs'and'performance'
Outcome(• New'test'technique'successfully'developed'and'tested'• Fan'3p'clearance'held'to'0.005”'with'ac3ve'nacelle'
posi3oning'system;'fan'performance'maintained'• Isolated'rotor'noise'sources'iden3fied'and'characterized'
40
SDT'Fan'Model'
www.nasa.gov
Rota3ng'Rake'
108
64
204
0322416
8
0-8
-16
-24
-32
-40
125120115110105100
95
PWL (dB)
PWL (dB)
Circumferential Mode (m-order)Rad
ial Mo
de (n-
order)
95
100
105
110
115
120
125
41
• Extensive'fan'noise'database'for'a'variety'of'fans'covering'a'full'range'of'fan'pressure'ra3os'and'3p'speeds.'
• Includes'noise'data'from'research'fans,'prototype'fans,'and'produc3on'engines.''
• Only'combined'inIduct'and'farfield'noise'database'for'low'speed'fans.'
SIGNIFICANCE:(The(Rota3ng'Rake'is'a'oneIofIaIkind'measurement'system'that'provides'a'complete'map'of'turbofan'duct'modes'(magnitude'&'phase).''This'measurement'system'has'contributed'to'development'of'engine'noise'reduc3on'technology.''
www.nasa.gov
Phased'Array'Measurements'
42
Experiment'
Simula3on'
Used'to'locate'noise'sources,'relies'heavily'on'tailored'data''processing'techniques,'e.g.'beamforming'
www.nasa.gov 43'
Ques3ons?'