Aircraft Engine Noise Research and Testing at the NASA Glenn Research Center

Aircra&'Engine'Noise'Research'and'Tes3ng'at'the'

NASA'Glenn'Research'Center '

Dave'Ellio;'

NASA'Glenn'Research'Center,'Acous3cs'Branch'

March'25,'2015'

David.M.Ellio;@nasa.gov '

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

www.nasa.gov

Acous3cs'Branch'within'NASA'Glenn'Organiza3on'

Office of the Director (A) Director James M. Free Deputy Director (A) Associate Director (A) NASA Safety Center (N) Associate Director for Strategy (A) Dr. Janet L. Kavandi Janet L. Watkins Alan H. Phillips Dr. Howard D. Ross Aeronautics Safety and Mission Facilities, Test and Center Operations Research and Space Flight Directorate (K) Assurance Manufacturing Directorate (C) Engineering Systems Directorate (Q) Directorate (F) Directorate (L) Directorate (M) Therese M. Griebel Robyn N. Gordon Anita D. Liang Thomas W. Hartline Dr. Rickey J. Shyne Bryan K. Smith ` Office of Technology Office of the Plum Brook Office of Diversity and Office of the Chief Office of Human Office of the Chief Incubation and Chief Counsel (G) Station (H) Equal Opportunity (E) Information Officer (V) Capital Management (J) Financial Officer (B) Innovation (T) Laurence A. Sivic J. William Sikora David L. Stringer Lynda D. Glover Sean M. Gallagher Dr. John M. Sankovic Lori O. Pietravoia PS–01242–0414 www.nasa.gov ver. 03 /13/ 2015

Enclosure 1 Research and Engineering Directorate

Research and Engineering Directorate (L) Management Support and Chief Engineer Integration Office Office (LA) (LB) Communications Systems Materials and and Intelligent Engineering and Propulsion Division Power Division (LE) Structures Division Systems Division Architecture Division (LT) (LM) (LC) (LS) For more information on Glenn’s Organizational Structure please visit: http://www.grc.nasa.gov/WWW/OHR/Orglist / Glenn Research Center at Lewis Field www.nasa.gov

Propulsion*Division*

Enclosure 2 Propulsion Division (LT) Chemical and Thermal Propulsion Systems Icing Branch (LTI) Propulsion Systems Analysis Branch (LTA) Branch ( LTR ) Turbomachinery and Electric Propulsion Acoustics Branch (LTV) Turboelectric Systems Systems Branch ( LTS ) Branch (LTE) Combustion Physics and Inlets and Nozzles Branch Thermal Systems Branch Reacting Systems Branch (LTT) (LTN) (LTX) Fluid Physics and Engine Combustion Fluid and Cryogenic Transport Processes Branch (LTC) Systems Branch ( LTF ) Branch (LTZ) For more information on Glenn’s Organizational Structure please visit: http://www.grc.nasa.gov/WWW/OHR/Orglist / Glenn Research Center at Lewis Field 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

U.S. Subsonic Transport Noise Goals '

! 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.

-52 * 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.

*** CO emission benefits depend on life-cycle CO per MJ for fuel and/or energy source used.

2 2e www.nasa.gov 8'

Subsonic Aircraft Noise Levels & Research Goals

10.0 B-707-100 DC8-20 Chapter 2 B-737-200 B-737-200 DC9-10 B-727-200 B-727-100 B-747-100 B-747-200 Chapter 3 A300B4-620 0.0 B-747-200 B-727-100 B-747-300 DC-10-40 Average B-747-SP MD-82 B-747-200 Noise A300-600R MD-80 MD-87 Chapter 4 1992 Small Twin Ave. Production A300 Level MD-11 A330-300 757-200 A310-222 B-737-800 B-737-300 B-737-900 Relative 1997 Small Twin Baseline Chapter 14 A320-214 A320-232 767-300ER B-777-300 to 747-400 A318-112 B-737-900ER 777-200 Chapter 3 MD-90-30 A340-541 (EPNdB) B-787 A330-243 -10.0 B-747-8F A380-841 AST TRL 6 Goal N+1 TRL 4-6 QAT TRL 4 Goal Goal N+2 TRL 4-6 Goal -20.0 1960 1970 1980 1990 2000 2010 2020 www.nasa.gov 9' Year of Certification

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.'

www.nasa.gov

Cross'Sec3onal'Drawing'of'Turbofan'Model'used'in'

Wind'Tunnel'Tes3ng'

www.nasa.gov

LTV/ Acoustics Branch

Jet Flow Turbulence via PIV

'

Honeywell Engine Test

Noise Diagnostics

• Concept Investigation • Engine Noise Source Identification GTF Fan Jet Flow & Noise Simulation

Noise Prediction

Jet Flow Prediction • Model Development • Simulations Jet Flow PIV Data Fan Noise Prediction

Noise Reduction

• Concept Development • Testing & Evaluation Swept Stator for Fan Noise Reduction Nozzle Chevrons for Jet Noise Reduction Trailing Edge Blowing for Fan Noise Reduction www.nasa.gov 12

Noise'Reduc3on '

Source Noise, Attenuation, Cancellation

Exhaust Systems

Acoustically Over-the-Rotor treated soft Model hardware metal foam

Propulsor

vanes acoustic treatment fan case Passive 3-D nozzle concepts Active control of jet M'1.3'Jet' Actuator'Off' Actuator'On' www.nasa.gov

Diagnos3cs '

Phased Arrays, PSP, PIV, HW/HF, CMFI No

Rotating Rake, FF Microphone

Pylon Pylon Array Array Peak Peak Level Level Flush Kevlar In a cooperative effort with NAVAIR, phased Acoustic Cover array measurements were obtained for an F404 engine with a modified nozzle that included chevrons Particle Image Velocimetry (PIV) Pressure Sensitive Paint Tip vortex www.nasa.gov 14'

Predic3on '

Δ Model SPL:

Empirical (ANOPP), RANS Based, Non-Linear High Order

TCON C0 Z1 160 160 Broadband 140 140 ) ) ° ° FEGV Wake Interaction, RANS Based Aeroacoustic 120 120 Stator Simulation 100 100 (BASS) Code, 80 80 ANCF Polar Angle from Inlet ( Polar Angle from Inlet ( 60 60 simulation, high order, high -1 0 -1 10 10 10 accuracy Strouhal Number dPSD = (PSD Modeled) – (PSD Measured) Fine Turbo, Open Rotor RANS Δ Twin Jet Effect: Sample, Δ SPL SPL: M = 1.33, T = 1.76, M = 0.25 a sr fj TCON C90 Z1 TCON C0 Z1 TCON C0 Z4 TCON C0 Z9 160 160 160 160 160 3

Open

140 140 140 ) ) ) ° ° ° 120 120 120 140 140 ) )

Rotor

° ° 100 100 100 80 80 80

RANS 120 120 Polar Angle from Inlet ( Polar Angle from Inlet ( Polar Angle from Inlet (

60 60 60 -1 0 -1 0 -1 0 10 10 10 10 10 10 Strouhal Number Strouhal Number Strouhal Number 100 100 TCON C90 Z1 TCON C90 Z4 TCON C90 Z9 160 160 160 140 140 140 ) ) ) -1 ° ° ° 80 80 120 120 120 100 100 100 Polar Angle from Inlet ( Polar Angle from Inlet ( -2 60 60 80 80 80 Polar Angle from Inlet ( Polar Angle from Inlet ( Polar Angle from Inlet ( 60 60 60 -3 -1 0 -1 -1 0 -1 0 -1 0 10 10 10 10 10 10 10 10 10 Strouhal Number Strouhal Number Strouhal Number Strouhal Number www.nasa.gov 15'

Distribu3on'by'Technical'Focus' '

www.nasa.gov Facili+es&and&Advanced&Tes+ng&Techniques&for& Database&Genera+on&and&Concept&Evalua+on&for& Aero-acoustic Propulsion Lab Exhaust&Systems,&Fan&Systems,&Open&Rotors,&and& small&engines.& 9x15/8x6 Wind Tunnel Acoustical Advanced Noise Testing Small Hot Jet Acoustic Rig Control Fan Lab (ATL) (SHJAR) (ANCF) CW-17 Free Jet Facility Nozzle Acoustic Test Rig (NATR) L www.nasa.gov 17'

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. & 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)' Highly'flexible,'fundamental'test'bed.'' Mul3ple'configura3ons,'including'rotor'alone.'

4Ifoot'diameter'ducted'fan' Low'speed:'(variable)'''' ' ~1800'rpm,' V '~375' & /sec,' M '~'0.15' 3p duct Used'to'provide'aeroIacous3c'database'and'to'evaluate' noise'reduc3on'technologies' Data'acquired'by'externally'clocking'data'system'from' rig'tachometer'signal' 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.)) 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.'

www.nasa.gov 19

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'

www.nasa.gov www.nasa.gov www.nasa.gov www.nasa.gov 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&degrees& 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:'' Linear'Array' 3' Mic 'Traverse' • Design'and'test'techniques'and'compare'with' Auto Spectra of Traversing Microphone vs Linear Array Cross Spectra at 90 degrees relative to Rear Rotor Pitch Axis for Historical Baseline at 100% Design Speed, M=0.2 present'acquisi3on'methods' 6 dB Plate Correction included for Linear Array 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' PSD, dB • Con3nuous'traverse'has'shown'excellent'comparison' with'discrete'traverse'and'has'ability'to'save'3me' 0 2000 4000 6000 8000 10000 Frequency, Hz www.nasa.gov

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'

'

www.nasa.gov www.nasa.gov

deciBels '

!

!

! ! = 10 ∗ !"# !

!" !"

!

!"#

!

! ! = 2 0 ∗ !"# ( ) !

!" !"

!

!"# ! !

! ! = 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

Fan'Noise'Reduc3on'Technologies '

• 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' 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' 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' ADP'Liner'Loca3ons' • 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' Max'Flow'Advanced'Casing'Treatment' www.nasa.gov

A&'Duct'Treated'Spli;er '

Objec3ve:'' • Reduce'a&'fan'noise' • Keep'performance'losses'to'minimum' Approach:' A&'' Spli;er' • 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' Black - Hard wall Nacelle • Spli;er'did'not'show'expected'noise' Red - Treated Nacelle (DDOF) Blue - Treated Nacelle with Treated Splitter reduc3on'possibly'due'to'tunnel' ' background'noise'or'moun3ng'method' • Sta3c'test'did'show'spli;er'provided' a;enua3on'at'design'frequency' SPL,' • Performance'loss'kept'to'1%'of'thrust'and' dB' was'primarily'due'to'skin'fric3on' • Added'technology'such'as'microIblowing' could'reduce'skin'fric3on' kHz' ADP Takeoff - 136 degrees

'

www.nasa.gov

Over'the'Rotor'–'So&'Vane'Concepts '

Conclusions'

Objec3ve:'

• OTR'treatment'not'effec3ve'in'reducing'noise' • Use'treatment'over'the'rotor'to'reduce' rotor'alone'noise' unlike'other'previous'tests'had'shown' • Reduce'rotor/stator'noise'at'source' • So&'Vanes'showed'PWL'reduc3ons'on'the' using'so&'vanes' order'of'1'dB'rela3ve'to'hard'vanes'for'certain'

sha&'speeds' Approach:'

• Design'and'Test'concepts'on'turbofan'' '''''model'in'9x15'LSWT' Over'the'Rotor'Treatment' So&'Vanes' 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)'

OASPL,'dB'

• 2%'blowing'rate'op3mum,'about'2db' OASPL'noise'reduc3on'rela3ve'to' baseline'across'spectrum'

%'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' 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' SDT'Fan'Model' www.nasa.gov

Rota3ng'Rake '

• 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.'' ) (dB) dB ( PWL PWL -40 -32 -24 -8 -16 Circumferential (n-order) Mode Mode 40 (m-order) Radial www.nasa.gov

Phased'Array'Measurements '

Used'to'locate'noise'sources,'relies'heavily'on'tailored'data''

processing'techniques,'e.g.' beamforming '

Experiment' Simula3on' www.nasa.gov

Ques3ons? '

www.nasa.gov 43'