Shipboard Noise Control on US Navy Aircraft CarriersNHCA Conference St. Petersburg, FL February 24, 2013

Jeffrey M. KomrowerNoise Control Engineering, Inc.

Kurt YankaskasOffice of Naval Research

Boyz from NoiseWe can’t wait to attenuate

Net Result of Noisy Systems in the Military

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• NIHL decreases quality of life and affects warfighter performance

• NIHL disabilities most prevalent by far with over 1.5 million veterans affected

• Annual costs well over $1.2 billion/year

• Aircraft Carriers one of noisiest platforms

Are Current Systems Noisy

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Noise Levels in Navy & Marine Corps

70 80 90 100 110 120 130 140 150 160 170 180

Navy Band

Engine Rooms

USMC AAAV

Aircraft Cockpits

Carrier Decks

Single HP Required (85 dB)

Double HP Required (104 dB)

Max protection w/ double HP (115 dB)

Aircraft Source Levels on Flight Deck Exceed 150 dBA

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Gallery Deck on CVN68 Class Aircraft Carriers

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• Many of the 5000 crew members live and work on the Gallery Deck – just under the flight deck

• Aircraft noise permeates into that level causing many spaces to exceed US Navy exposure limits of 85 dBA

• OPNAVINST 5100.23G states that the abatement of hazards, which includes noise, are to be first addressed through engineering or administrative controls. Where these controls are not feasible, appropriate PPE is to then be provided

For a level of 105 dBA, after 8 launches, noise exposure limits would be exceeded

Gallery Deck Noise Levels Getting Worse

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Noise Levels for CAT 2 F/A 18 C/D Hornet LaunchJSF Levels Already Known to be up to 10 dB higher than F18

Objective: Develop Engineering Controls to Reduce Noise Levels from Flight Operations on Gallery Deck

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Technical Approach:• Predict noise levels using Designer NoiseTM software• Test program undertaken on USS Dwight D. Eisenhower (CVN69)

Area of focus: “12-pack” area under Catapult #2 Baseline measurements taken prior to application of controls Apply spray-on damping material on bulkheads Retake measurements to determine effectiveness

• Use test data to: Validate noise model accuracy (treated and untreated) Validate source level assumptions Verify effectiveness of treatment Quantify acoustic and structureborne energy paths into gallery deck

• Use validated noise models to develop optimized noise control treatment plan for full gallery deck

Design Tools: Designer NOISETM

• Energy flow from sources into ship compartments can be accurately modeled

• Relative contribution of different surfaces to overall noise levels predicted

• Noise control treatments evaluated• Optimized noise control treatment schemes

developed (effectiveness, cost, weight)

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Acoustic Modeling with Designer NOISE™

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Accurate modeling needed to translate physical system to optimal solution:

1) Physical System

3) Designer NOISE CAD Model Option number

Noise Reduction, dB

Treatment description

I 5 1.Damping spray 3‐4 mm thick on the structural bulkheads

2. Damping spray 1 mm thick on the joiner bulkheads

II 12 Option I +1. 2” thick additional fiberglass

layer on the overhead2. 2” thick fiberglass layer on the

structural bulkhead3. Floating floor (3 mm thick steel

plating+2” thick fiberglass

4) Optimal Solution

2) Source/Path

USS Dwight D. Eisenhower (CVN69) Test Program Summary

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Area of focus: Gallery Deck under JBD #2 for Catapult 2 launches

USS Dwight D. Eisenhower (CVN69) Test Program Summary

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• Baseline measurements accomplished in August 2011 in selected areas• Damping material installed in selected compartments in February 2012• 107 channels of instrumentation installed (microphones and accelerometers)• Data acquired for over 90 launches over 3 day period in April 2012• Measurements also taken using an acoustic array to determine primary paths

of acoustic energy into compartments

Acoustic Holography Array

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SR-03-92-0-L Cat 2 Launch - Hornet

Looking FWD Looking Aft

Structural Bulkhead Non-Structural Bulkhead

Overall SPL in SR-03-92-0-L: 91 dB(A)

Innovative Treatments: Spray-On Damping

• Reducing vibration on surfaces effective way to reduce noise

• Spray-on damping material lighter in weight than traditional damping tiles

• Easier and faster to apply than damping tiles and can be applied to areas where traditional methods cannot access

• Product was developed under SBIR program by Tech21

• Application of damping material resulted in 5-7 dBA noise level reduction without full surface coverage

Test Results: Models Correlated Well with Test Data

• Designer NOISE™ accurately predicted noise levels for treated and untreated spaces

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Untreated space

Treated space

Developed Optimized Noise Control Treatment Schemes

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Summary and Conclusions

• Designer NOISETM acoustic modeling software accurately predicted noise levels for treated and untreated compartments

• Tech21 Silent-R spray-on damping treatment shown to be effective resulting in noise reduction of 5-7 dBA in treated compartments

• Data measured from on-deck microphones and accelerometers on flight deck underside was successfully used to determine inputs to acoustic models and validate source levels

• Acoustic array data verified surfaces that were the most important contributors to overall noise levels in measured compartments and also showed a significant reduction in acoustic “hot spots” after treatment

• Designer NOISETM can be used to develop an optimized noise reduction plan wrt cost, weight and effectiveness of treatment options

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Next Steps

• Implement noise control solutions using navy noise control technology

• Designer NOISETM is currently being used to predict noise levels and develop noise control treatment plan for high noise areas throughout the Gallery Deck

• Engineering controls scheduled to be installed starting 2015 as ships enter maintenance overhaul periods

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Acknowledgements

• Kurt Yankaskas and the Office of Naval Research for their support throughout this effort and over the years

• Program Executive Office (PEO) Carriers especially Calvin Benson, Eric Pitt and Ernie Chambers for their help and support in the planning and execution of the testing

• Crew of USS Dwight D. Eisenhower (CVN69) for all of the assistance and cooperation during the installation of the noise controls and willingness to work with the team to make sure we got the data needed during air operations

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Questions?

Are Current Systems Noisy

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