Noise and Noise Reduction in Supersonic Jets

Noise and Noise Reduction in Supersonic Jets Philip J. Morris and Dennis K. McLaughlin The Pennsylvania State University Department of Aerospace Engineering Presented at FLINOVIA 2017 State College, PA April 2017 1

Outline 3 Brief historical perspective Noise reduction methods Commercial Military Successful concepts Chevrons Corrugated seals Fluidic inserts Discussion

Historical Perspective 8 corrugated silencers for Conway engines on a 707-420 Bypass ratio, 0.25 4

Early Suppression Ideas Auxiliary jets 5

Modern High Bypass Ratio Turbofans General Electric GE90-115B. Bypass ratio, 9:1 6 PW1000G. Bypass ratio, 12:1

Tactical Fighter Aircraft F-35C Lightning II, powered by the P&W F135 7 F/A-18 Super Hornets, powered by the F414-GE- 400 Bypass ratio < 1

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 8

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 9

Chevrons at Exit Plane Side and aft looking forward photograph of typical chevron configuration. 10 From Martens & Spyropoulos (2010) F404-400

Chevrons at Exit Plane F404-400: maximum afterburner 11 From Martens & Spyropoulos (2010)

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 ; 12

Experiments with Corrugated Seals Good noise reductions at model scale The inserts were designed to perform optimally at one jet condition (takeoff). At higher altitude conditions, the corrugations can negatively effect engine performance. 13 Murray and Jansen (2013)

Corrugated Inserts Full scale engine tests Engine on Test Stand Aft quadrant 14

15 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

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. 16 CAD Image Installed nozzle at Penn State

17 Noise Benefit of Fluidic Inserts SPL per unit St (db//(20 Pa 2 )) NPR = 3.0 M j =1.36 TTR = 3.0 M d =1.65 120 120 120 120 120 Far field spectra and OASPL s ; 2012 = 60, IPR = 3.0 result M = 1.36 j NPR = 3 TTR = 3.0 30 40 60 90 120 Baseline 3 Corr., D inj = 0.06D, m ratio = 3.8% 20 db 0.01 0.1 1 10 Strouhal Number 3FID06B 3FID06V -6-4 -2 0 2 OASPL (db) 30 36 40 43 46 50 55 60 65 70 80 85 90 93.5 100 105 110 115 Polar angle from downstream direction Polar angle (Degree),

Time History Baseline Three Fluidic Inserts Present experiments Scaled Comparison 18 18 Martens, Spyropoulos & Nagel (2011)

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. 1 inch Reynolds No. ranges: PSU 450,000 to 660,000 GEA ~ 2.5 x 10 6 5 inchs 19 19

Adaptation of the Penn State Blowing System to GE Scale Injectors Fully-Assembled CAD model 20 High pressure air feed lines for injectors

Moderate Scale Experiments Far Field Jet Noise Comparison (rear arc: 140 o ) Industry Scale Baseline vs Fluidic Inserts Noise Reduction Md = 1.65, Mj = 1.36 - Over-expanded Jet Spectra 130 120 6.5 db 110 SPL (db) 100 90 80 NPR 3.0 No Injection NPR 3.0 IPR 3.0 21 70 10 100 1000 10000 100000 Frequency (Hz)

Far Field Jet Noise OASPL Reduction - GE, Industry Scale Far Field Jet Noise Comparison Industry Scale Baseline vs Fluidic Inserts Noise Reduction Md = 1.65, Mj = 1.36 - Over-expanded OASPL Reduction 22 22 Polar Coordinates Industry standard

GE Results Scaled to Aircraft Size 50 ft sideline - Carrier Environment 23

Steady RANS Simulations for Design Guidance (Morris, Kapusta, Lampenfield) 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 24 x Vorticity Contours 24

Noise and RANS Correlation Compare flow changes with measured noise reductions Seek surrogate for noise reduction in flow properties Integrated TKE, streamwise vorticity, Q- criterion 25

26 Integrated TKE

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 2 nd 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 27

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. 28