adbm overview presentation 2015-09 links

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9/28/2015 Mark S. Wochner, Ph.D. | President & CEO Advanced Approaches in Underwater Noise Abatement

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Page 1: AdBm Overview Presentation 2015-09 Links

9/28/2015Mark S. Wochner, Ph.D. | President & CEO

Advanced Approaches in Underwater Noise Abatement

Page 2: AdBm Overview Presentation 2015-09 Links

Technology Background

BACKGROUND: OIL AND GAS NOISE– Research started in 2009– Drilling, seismic surveying, pipe laying, support ship– All-purpose noise abatement system

PREVIOUS METHOD: FREE BUBBLES– Low frequency attenuation requires unstable large bubbles– Limited performance for small bubbles (~10 dB)

OUR APPROACH: BUBBLE RESONANCE– Frequencies of interest: 30 Hz to 200 Hz– Desired noise level reduction: >10 dB

Page 3: AdBm Overview Presentation 2015-09 Links

AIR BEHAVES LIKE A MASS-SPRING SYSTEM– larger bubbles → lower resonance frequency– energy from the acoustic wave goes into resonating the bubble

SMALL BUBBLES DON’T RESONATE AT DESIRED FREQUENCIES

LARGE FREE BUBBLES ARE UNSTABLE, SO WE CAPTURE THE AIR

Bubble Resonance

Commander & Prosperetti, JASA 85, 732-746 (1989)

Monodisperse distribution of bubbles: Bubble radius = 6 cm

Void fraction β = 0.01

Page 4: AdBm Overview Presentation 2015-09 Links

AIR BEHAVES LIKE A MASS-SPRING SYSTEM– larger bubbles → lower resonance frequency– energy from the acoustic wave goes into resonating the bubble

SMALL BUBBLES DON’T RESONATE AT DESIRED FREQUENCIES

LARGE FREE BUBBLES ARE UNSTABLE, SO WE CAPTURE THE AIR

Bubble Resonance

Commander & Prosperetti, JASA 85, 732-746 (1989)

Monodisperse distribution of bubbles: Bubble radius = 6 cm

Void fraction β = 0.01

Church, JASA 97, 1510-1521 (1995)

Page 5: AdBm Overview Presentation 2015-09 Links

AIR BEHAVES LIKE A MASS-SPRING SYSTEM– larger bubbles → lower resonance frequency– energy from the acoustic wave goes into resonating the bubble

SMALL BUBBLES DON’T RESONATE AT DESIRED FREQUENCIES

LARGE FREE BUBBLES ARE UNSTABLE, SO WE CAPTURE THE AIR

a0 = 12 cm

a0 = 8.02

a0 = 6 cm Fixed Void Fraction: 0.5%

0.5%

1%

2%

Fixed radius:a0 = 8.02 cm

Two unique controls:

Control target frequencies

Control amount of attenuation

Bubble Resonance

Page 6: AdBm Overview Presentation 2015-09 Links

SOURCES OF ENERGY DISSIPATION

– Heat transfer from gas inside resonator to surrounding fluid

– Work done by the resonator:o Viscous losses in surrounding fluido Viscoelastic stresses in shell (fully or partly encapsulated resonators)o Re-radiation of acoustic energy (phase incoherent)

energy from sound wave goes into oscillating the resonator dominant loss mechanism for large resonators

NOTE: Higher Q resonators are better oscillators and better attenuators

Energy Losses

Page 7: AdBm Overview Presentation 2015-09 Links

Acoustic Demonstration

Demonstration Video: Low-Frequency Version(For High-Fidelity Sound Systems)

http://youtu.be/sKf4ibzJ-Jc

Demonstration Video: High-Frequency Version(For Laptop Speakers, etc)

http://youtu.be/BHupQqkx3Hk

Page 8: AdBm Overview Presentation 2015-09 Links

no bubbles

N = 150, β = 0.02

N = 70 β = 0.01

N = 35 β = 0.005

a0 = 8 cm

Results of lake tests in 35 m of water for continuous and impulsive noise

N = 35, β = 0.005

N = 70, β = 0.01

N = 150, β = 0.02

no bubbles

Continuous Noise Impulsive Noise

Validation

Page 9: AdBm Overview Presentation 2015-09 Links

N = 35, β = 0.005

N = 70, β = 0.01

N = 150, β = 0.02

no bubbles

Continuous Noise Attenuation Prediction

Validation & Prediction

Page 10: AdBm Overview Presentation 2015-09 Links

Helmholtz resonators’ behavior is dependent on a number of factors: volume, neck length, and aperture size

Helmholtz resonance is often used in sound suppression:

Bass Traps

Car exhaust systems

Vair

LA

WaterADVANTAGES:

– More customizable & predictable– Better performance at depth– More rigging & manufacturing options available– Lower ballast requirements

Helmholtz Resonance

Page 11: AdBm Overview Presentation 2015-09 Links

2014 Demo Panel

Noise Abatement Concept

Page 12: AdBm Overview Presentation 2015-09 Links

Close up of system on articulating pile gripper

System deployed around pile under pile gripper

Noise Abatement Concept

2014 Demo Panel

Page 13: AdBm Overview Presentation 2015-09 Links

RECENTLY COMPLETED OFFSHORE DEMONSTRATION – Butendiek Wind Farm– Monopile diameter: 6.8 m– Project developer: WPD– Installation company: Ballast Nedam– Crew, vessel, support supplied by Ballast Nedam– Three AdBm personnel involved in test

INSTALLATION OF SYSTEM IN NORTH SEA– Four installations of the noise abatement system occurred– No installation issues; fast deployment

Offshore Demonstration

Page 14: AdBm Overview Presentation 2015-09 Links

Offshore Demonstration

The IHC Merwede NMS

Page 15: AdBm Overview Presentation 2015-09 Links

Three different resonator sizes

Offshore Demonstration

Page 16: AdBm Overview Presentation 2015-09 Links

Deployed system in the water Experimental setup

Offshore Demonstration

Page 17: AdBm Overview Presentation 2015-09 Links

Without Noise Abatement

With Noise Abatement

Pile Range (m) Number of Strikes Baseline (dB) Panel (dB) Difference (dB) Max Reduction (dB)

BU-21 285 668 183.3 ± 0.7 164.2 ± 2.3 19.2 ± 2.4* 36.8*

Offshore Demonstration

Page 18: AdBm Overview Presentation 2015-09 Links

NEW ACOUSTIC RESONATORS– Injection-molded, positively buoyant materials– Multiple sizes for varying depths, resonance frequencies, etc.– More consistent performance at depth

Our resonators vs.Free Bubbles (f0 = 100 Hz)

1/5 the volume at surface1/17 the volume at 40 m

Less air = less buoyancy → less ballast, simpler framework

Modern Noise Abatement System

1/50 the air volume of balloons at 40 m

Page 19: AdBm Overview Presentation 2015-09 Links

440 kg static load tested Slight plastic deformation afterward

NEW ACOUSTIC RESONATORS

Modern Noise Abatement System

Page 20: AdBm Overview Presentation 2015-09 Links

RESONATOR FRAMEWORK– Fully protected within metal deployment framework

– Framework organized as slats– System stacks like Venetian blinds– Resonator slats open below surface– Functional elements protected

Aluminum/SteelFramework

Chain guides

Resonators fully protected when slats are stacked

Modern Noise Abatement System

Page 21: AdBm Overview Presentation 2015-09 Links

THE ASSEMBLED SYSTEM– Panels arranged around pile and deployed using winches– Mounted to pile gripper or directly to vessel– Complete, tunable, passive system

SystemSlats

Resonators

Modern Noise Abatement System

Page 22: AdBm Overview Presentation 2015-09 Links

SEISMIC SURVEYING– metal Helmholtz resonators perform best– well-suited to air gun noise abatement– system of towed bodies can be designed

SHIPPING & DREDGING NOISE– ship treated directly with hydrodynamic system– system of fencing can be used to protect an area– long-term, no energy solution

EXPLOSIVES– UXO removal, explosive demolitions (End View)

Noise abatement panels

Airgun

Noise abatement panels

Airgun

(End View)

Acoustic resonator system absorption

Other Applications

Page 23: AdBm Overview Presentation 2015-09 Links

Acoustic resonator systems have tunable, predictable performance

System has demonstrated up to 50 dB of noise reduction

New resonator design is more robust, easier to manufacture, has better depth performance, and requires 25% the ballast

Can be used to treat other noise sources: ships, air guns, explosives

Summary