impact of air injection on jet noiseimpact of air
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Impact of Air Injection on Jet NoiseImpact of Air Injection on Jet Noise
Brenda Henderson and Tom NorumNASA Langley Research Center
Fall Acoustics Technical Working GroupDecember 4 – 5, 2007
Cleveland, OH
Objective
D t i i t f fl idi hDetermine impact of core fluidic chevrons on noise produced by dual stream jets
•Broadband shock noise - supersonic
Mi i i b i d i•Mixing noise – subsonic and supersonic
NATR
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Jet Noise Sources
Fine Grain Turbulence
Large Scale Turbulence (Mach Wave
Broadband
Shock Noise Mixing Noise
(Mach Wave Emission)
Screech
• Mixing noise• Mach wave radiation
Crackle• Shock associated noise
BroadbandBroadbandDiscrete
• STOVL noise/tones Mach WavesCourtesy of D. Papamoschou
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NASA Langley (LSAWT)
Low Speed Aeroacoustics Wind Tunnel
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Generation II Fluidic ChevronsAir Supply
Pylon
Slotted core no le
Fan Nozzle
Slotted core nozzle
Fluidic Chevron Core Nozzle
N l d i th lt f t hi b t NASA L l
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Nozzle design was the result of a partnership between NASA Langley Research Center and Goodrich Aerostructures under SAA1-561
Generation III Fluidic Chevrons
• Core fluidic chevron nozzlenozzle
• 8 injectors– 4 pairs independently p p y
controlled• No common plenum
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Fluidic Chevron Nozzles
BPR 5
8IFan Flow
Core Flow Injection Flow
6I 8I
Gen II Gen IIILine 1Line 2Line 2Line 3Line 4
Three Air Injection Nozzles
122o Pylon Angle
Three Air Injection Nozzles• 6I steep injection• 6I shallow injection
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• 8I steep injection– azimuthal controlMicrophone
Chevron Mixing Enhancement
• Enhanced mixing shortens potential core and reduces
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Enhanced mixing shortens potential core and reduces volume of acoustic sources
Characteristics of Fluidic ChevronsX/Dc = 8
Tt, K
Baseline
θ = 90oTakeoff
Mach 0.28
8IS
PL
(dB
)
5 dB
θ 90
8IFluidic Chevron - Generation IIMechanical ChevronBaseline
6I80 10 100 1000 10000
Frequency (Hz)
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Experiments
NPRc TTRc
1.93 12 04 1
Single Stream Experiments2.04 12.17 12.30 2.5
• Fan stream operated at tunnel conditions
Dual Stream Experiments
NPRc TTRc NPRf TTRf
1.56 2.66 1.75 1.161.61 2.13 2.23 1.051.82 2.13 2.23 1.05 Dual Stream Experiments2.04 2.39 2.23 1.051.61 2.26 2.35 1.171.82 2.26 2.35 1.172.04 2.39 2.35 1.172.17 2.46 2.35 1.172.04 2.39 2.45 1.042.17 2.46 2.5 1.05
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Free-stream Mach number = 0.10
Baseline90
Baseline nozzle and injection nozzles with70
80
B)
θ = 61oShock Noise
injection nozzles with IPR = 1.0 have similar noise characteristics50
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SP
L (d
B
BaselineGen II Steep Injector, IPR = 1.0Gen III, IPR = 1.0
30
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100 1000 10000 100000Frequency (Hz)
,
95θ 148
NPR = 2 17
Frequency (Hz)
75
85B
)θ = 148o
NPRc = 2.17
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SP
L (d
B
BaselineGen II Steep Injector, IPR = 1.0Gen III, IPR = 1.0
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100 1000 10000 100000Frequency (Hz)
Effect of Increasing NPRc90
70
80
90
) Well defined shock noise
θ = 61o
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L (d
B
NPRc = 1.93NPRc = 2 04
Well defined shock noise peak at NPRc = 2.17
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100 1000 10000 100000
NPRc 2.04NPRc = 2.17
95Frequency (Hz)
75
85
95
B)
θ = 148o
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55
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L (d
B
NPRc = 1.93NPRc = 2.04NPRc = 2 17
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35
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100 1000 10000 100000Frequency (Hz)
NPRc = 2.17
90
Injection at Low Supersonic Speeds
70
80
90
)
• Injector noise is is not suppressed
θ = 61o
50
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L (d
B)
IPR = 1.0IPR = 2.0IPR = 4.0
• Increases in IPR produce reductions in mixing noise near peak
30
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100 1000 10000 100000F (H )
95
mixing noise near peak jet noise angle
Frequency (Hz)
75
85B
)θ = 148o
NPRc = 1.93
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55
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SP
L (d
IPR = 1.0IPR = 2.0IPR = 4.0
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35
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100 1000 10000 100000Frequency (Hz)
Injection for Well-Defined Shock Noise90
70
80
90
Increases in IPR produce red ctions in shock noise
θ = 61o
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L (d
B)
IPR = 1.0IPR = 2 0
reductions in shock noise and mixing noise
30
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100 1000 10000 100000F (H )
IPR = 2.0IPR = 4.0
95Frequency (Hz)
75
85
95
B)
θ = 148o
NPRc = 2.17
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55
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SP
L (d
B
IPR = 1.0IPR = 2.0
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35
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100 1000 10000 100000Frequency (Hz)
0IPR = 4.0
Azimuthal Control for Shock Noise90
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80
90
B)
θ = 61oSignificant shock noise reduction can be achieved
50
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L (d
B
IPR All = 1.0IPR All = 4 0
with injection near pylon
%1121injectionm&
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100 1000 10000 100000Frequency (Hz)
IPR All 4.0IPR 1,2 = 4.0
95
%1.12,1 =core
injection
m&
q y ( )
75
85
95
B)
θ = 148oNPRc = 2.17
All
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L (d
B
IPR All = 1.0IPR All = 4.0IPR 1,2 = 4.0
1,2 All
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100 1000 10000 100000Frequency (Hz)
Impact of Injection on Sideline Directivity
110
106
108
dB)
104
106
OA
SP
L (d
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O IPR = 1.0IPR = 2.0IPR = 4.0
10045 60 75 90 105 120 135 150
Angle (deg)
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Angle (deg)
Injection at Subsonic Core and Fan Speeds90
70
80
90
B)
θ = 90o Mixing noise reduction can be achieved with injection near observation side of jet
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L (d
B
BackgroundIPR All = 2 3
%6.12,1 =injection
mm&
&near observation side of jet
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100 1000 10000 100000Frequency (Hz)
IPR All = 2.3IPR 1,2,3 = 1.4 & IPR 4 = 2.3
110
corem
Frequency (Hz)
90
100dB
)
BackgroundIPR All = 2.3IPR 1,2,3 = 1.4 & IPR 4 = 2.3
NPRc = 1.56NPRf = 1.75
70
80SP
L (d θ = 148oAll4
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60100 1000 10000 100000
Frequency (Hz)
75
Injection at Subsonic Core and Fan Speeds
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B)
Injection produces mixing noise reduction at
θ = 90o
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L (d
B
BackgroundIPR All = 2.3
peak jet noise angle with slight increase in high frequency noise at 90o
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10 100 1000 10000Frequency (Hz)
IPR All 2.3IPR 1,2,3 = 1.4 & IPR All = 2.3
90
frequency noise at 90
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80B
)
BackgroundIPR All = 2.3IPR 1,2,3 = 1.4 & IPR 4 = 2.3
NPRc = 1.56NPRf = 1.75
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L (d
B
θ = 148oNozzle IPR EPNL (EPNdB)
Injection Mass (% Core)
Baseline 90.4Air Injection All = 2.3 89.6 2.9Air Injection 1,2,3 = 1.4 & 4 = 2.3 89.4 1.6
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10 100 1000 10000Frequency (Hz)
Baseline Results at NPRf = 2.23100
80
90
100
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Increasing NPRc• Decreases shock noise
θ = 61o
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L (d
B
NPRc = 1.61, NPRf = 2.23
NPRc = 1.82, NPRf = 2.23
Decreases shock noise peak
• Increases mixing noise
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100 1000 10000 100000F (H )
NPRc = 2.04, NPRf = 2.23
110
near peak jet noise angle
Frequency (Hz)
90
100B
)θ = 148o
60
70
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SP
L (d
NPRc = 1.61, NPRf = 2.23
NPRc = 1.82, NPRf = 2.23
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50
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100 1000 10000 100000Frequency (Hz)
NPRc = 2.04, NPRf = 2.23
Injection at Subsonic Core Speeds100
80
90
100
) Increasing IPR decreases
θ = 61o
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SP
L (d
B)
IPR = 1.0IPR = 2.5
gshock peak
110
40
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100 1000 10000 100000F (H )
IPR 2.5IPR = 4.0
θ 148
90
100B
)Frequency (Hz)
NPR = 1 61
θ = 148o
60
70
80
SP
L (d
IPR = 1.0IPR = 2.5IPR = 4.0
NPRc = 1.61
NPRf = 2.23
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50
60
100 1000 10000 100000Frequency (Hz)
Azimuthal Control at Subsonic Core Speeds100
No noise reduction with Gen III nozzle due to low80
90
100
B)
θ = 61o
Gen III nozzle due to low mass flow rates or steeper injectors60
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SP
L (d
B
IPR All = 1.0IPR All = 4.0IPR 1,2 = 4.0
40
50
100 1000 10000 100000Frequency (Hz)
,
110
NPRc = 1.61NPRf = 2.23
q y ( )
90
100
110
B)
θ = 148o
All
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SP
L (d
B
IPR All = 1.0IPR All = 4.0IPR 1,2 = 4.0
1,2 All
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100 1000 10000 100000Frequency (Hz)
Injection at Supersonic Core Speeds100
80
90
100
)
θ = 61o
Increases in IPR produce
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L (d
B
IPR = 1.0IPR = 2.5IPR = 4.0
preductions in noise near peak jet noise angle
40
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100 1000 10000 100000F (H )
110Frequency (Hz)
90
100B
)θ = 148o
60
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SP
L (d
IPR = 1.0IPR = 2.5IPR = 4.0
NPRc = 2.04
NPRf = 2.23
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50
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100 1000 10000 100000Frequency (hz)
Injection at Subsonic Core Speeds100
80
90
100
)
θ = 61oIncreasing IPR• Has no impact on
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L (d
B)
IPR = 1.0IPR = 4.0IPR = 5.0
Has no impact on broadband shock noise
• Slightly reduces noise at
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100 1000 10000 100000F (H )
120
peak jet noise angle
Frequency (Hz)
100
110B
)θ = 148o
70
80
90
SP
L (d
IPR = 1.0IPR = 4.0IPR = 5.0
NPRc = 1.82
NPRf = 2.35
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60
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100 1000 10000 100000Frequency (Hz)
Points of Discussion
• Injection impacts shock structure and stream j pdisturbances through enhanced mixing
– May impact constructive interferenceMay impact constructive interference between acoustic sources
• High fan pressures may inhibit mixing produced by core injectorsp y j
– Fan stream injection may be required for better noise reduction
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better noise reduction
Future Plans
• Modification of Gen II nozzles to allow for some azimuthal control
• Will allow for higher mass flow ratesWill allow for higher mass flow rates• Will allow for shallower injection angles
Fl fi ld t d i 2008• Flow field study – spring, 2008• CFD analysis of flow
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