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Noise and Noise Reduction in Supersonic Jets

Philip J. Morris and Dennis K. McLaughlinThe Pennsylvania State University

Department of Aerospace Engineering

Presented atFLINOVIA 2017

State College, PA

April 2017

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Noise and Noise Reduction in Supersonic Jets

Philip J. Morris and Dennis K. McLaughlinThe Pennsylvania State University

Department of Aerospace Engineering

Presented atFLINOVIA 2017

State College, PA

April 2017

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Outline

Brief historical perspectiveNoise reduction methodsCommercialMilitary

Successful conceptsChevronsCorrugated sealsFluidic inserts

Discussion

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Historical Perspective

8 corrugated silencers for Conway engines on

a 707-420

Bypass ratio, 0.25

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“Early” Suppression Ideas

Auxiliary jets

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Modern High Bypass Ratio Turbofans

General Electric GE90-115B.Bypass ratio, 9:1

PW1000G. Bypass ratio, 12:1

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Tactical Fighter Aircraft

F/A-18 Super Hornets, powered by the F414-GE-

400

F-35C Lightning II, powered by the P&W F135

Bypass ratio < 1

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Noise Reduction Methods Purely passive devices

Chevrons, tabs and other nozzle lip devices Beveled nozzle geometry Offset stream - fan flow deflectors Corrugated seals

Deployable (and retractable) Passive devices Deployable flexible filaments.

Active Noise Suppression Unsteady nozzle actuation (plasma excitation)Microjet injection and fluidic chevrons Distributed blowing, “fluidic inserts”

Additional Concepts Inverted Velocity Profile Jet

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Noise Reduction Devices Purely passive devices

Chevrons, tabs and other nozzle lip devices Beveled nozzle geometry Offset stream - fan flow deflectors Corrugated seals

Deployable (and retractable) Passive devices Deployable flexible filaments.

Active Noise Suppression Unsteady nozzle actuation (plasma excitation)Microjet injection and fluidic chevrons Distributed blowing, “fluidic inserts”

Additional Concepts Inverted Velocity Profile Jet

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Chevrons at Exit Plane

Side and aft looking forward photograph of typical chevron configuration.

From Martens & Spyropoulos (2010)F404-400

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Chevrons at Exit Plane

From Martens & Spyropoulos (2010)

F404-400: maximum afterburner

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Corrugated Seals

Corrugations reduce jet noise by eliminating the peak of the BBSAN. They also produce streamwise vortices that increase mixing and reduces large scale structure noise.

The effect of nozzle interior corrugations and the noise suppression potential of using these in supersonic converging-diverging nozzles was pioneered by ;

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Experiments with Corrugated Seals

The inserts were designed to perform optimally at one jet condition (takeoff). At higher altitude conditions, the corrugations can negatively effect engine performance.

Murray and Jansen (2013)

Good noise reductions at model scale

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Corrugated InsertsFull scale engine tests

Engine on Test Stand

Aft quadrant

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“Fluidic Inserts”

The Penn State innovation being pursued is that of “fluidic inserts” generated by a pattern of blowing that produces a core flow that approximately replicates that of “hard-walled” inserts, and produces a similar acoustic benefit as nozzles with “conventional” inserts

The “fluidic inserts” are an “active control system” that can be modified or turned off

Program approach: Use laboratory “staged experiments” and numerical

simulations to build an understanding of the flow field with the distributed blowing to provide “noise reduction”

Demonstrate concept at moderate and full scale

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“On Demand” Noise Reduction using Fluidic Inserts

Distributed blowing in the diverging portion of the supersonic exhaust nozzle using “compressor air” that is less than 5% of the core mass flow.

CAD Image Installed nozzle at Penn State

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Noise Benefit of Fluidic Inserts Far field spectra and OASPL’s ; 2012

result

0.01 0.1 1 10

120

120

120

120

120

Strouhal Number

SPL

per u

nit S

t (dB

//(20P

a2 ))

TTR = 3.0

Mj = 1.36NPR = 3

20dB

= 60 , IPR = 3.0

Baseline3 Corr., Dinj = 0.06D , mratio = 3.8%

30

40

60

90

120

-6 -4 -2 0 2

30

36

40

43

46

50

55

60

65

70

80

85

90

93.5

100

105

110

115

OASPL (dB)

Pola

r ang

le (D

egre

e),

3FID06B3FID06V

NPR = 3.0Mj =1.36

TTR = 3.0Md =1.65

Polar angle from downstream direction

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Time History

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Scaled Comparison

Martens, Spyropoulos & Nagel (2011)

Baseline Three Fluidic Inserts

Present experiments

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Current Major Objective

• Major Objective: To extend the successes of the fluidic insert noise reduction method from University to Industry model scale as a logical first step toward implementation on a full scale aircraft.

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Reynolds No. ranges: • PSU 450,000 to 660,000• GEA ~ 2.5 x 106

1 inch

5 inchs

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Adaptation of the Penn State Blowing System to GE Scale

Injectors

High pressure air feed lines for injectors

Fully-Assembled CAD model

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Moderate Scale Experiments

Far Field Jet Noise Comparison (rear arc: 140o) Industry Scale Baseline vs Fluidic Inserts Noise Reduction

Md = 1.65, Mj = 1.36 - Over-expanded Jet Spectra

70

80

90

100

110

120

130

10 100 1000 10000 100000

SPL

(dB

)

Frequency (Hz)

NPR 3.0 No Injection

NPR 3.0 IPR 3.0

6.5 dB

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Far Field Jet Noise OASPL Reduction - GE, Industry Scale

Far Field Jet Noise Comparison Industry Scale Baseline vs Fluidic Inserts Noise Reduction

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Md = 1.65, Mj = 1.36 - Over-expanded OASPL Reduction

Polar CoordinatesIndustry standard

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GE ResultsScaled to Aircraft Size

50 ft sideline -Carrier Environment

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Steady RANS Simulations for Design Guidance (Morris, Kapusta, Lampenfield)

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Provide details of flow inside nozzle

Show the effects of: Number of injectors Location and orientation of

injectors Compute “shape” of

fluidic inserts Insight into detailed

insert flow structure

Total Temp. Contours

x Vorticity Contours

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Noise and RANS CorrelationCompare flow changes with measured

noise reductionsSeek surrogate for noise reduction in

flow propertiesIntegrated TKE, streamwise vorticity, Q-

criterion

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Integrated TKE

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Findings and Conclusions

Results of the experiments at GE Aviation demonstrated that significant levels of noise reduction were achieved with the industry size experiments

Scaling of noise benefits to full size aircraft at sideline distances found on aircraft carriers show dramatic noise benefits

2nd round experiments at GE Aviation planned for June 2017

RANS CFD simulations assisted in design and will be continued. Expanded to Hybrid RANS/LES simulations

Plan to extend this method to university-scale models of multi-stream variable cycle engines

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Acknowledgements

This research was supported by ONR Contract # N00014-14-C-0157, with Dr. Joseph Doychak and Dr. Knox Millsaps serving as Program Officers.

Steve Martens and Erin Lariviere at GE Aviation had a major role in the preparation of the GE experiments. Penn State activity benefitted from the participation of Scott Hromisin, Chris Shoemaker, J.D. Miller, Jessica Morgan, Dr. Russell Powers, Matt Kapusta, Jake Lampenfield and Chitrarth Prasad.