AdBm Overview Presentation 2015-09 Links

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

    Advanced Approaches in Underwater Noise Abatement

  • 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

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

    SMALL BUBBLES DONT 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 = 0.01

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

    SMALL BUBBLES DONT 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 = 0.01

    Church, JASA 97, 1510-1521 (1995)

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

    SMALL BUBBLES DONT 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

  • 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

  • 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

    http://youtu.be/sKf4ibzJ-Jchttp://youtu.be/BHupQqkx3Hk

  • no bubbles

    N = 150, = 0.02

    N = 70 = 0.01

    N = 35 = 0.005

    a0 = 8 cm

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

    N = 35, = 0.005

    N = 70, = 0.01

    N = 150, = 0.02

    no bubbles

    Continuous Noise Impulsive Noise

    Validation

  • N = 35, = 0.005

    N = 70, = 0.01

    N = 150, = 0.02

    no bubbles

    Continuous Noise Attenuation Prediction

    Validation & Prediction

  • 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

  • 2014 Demo Panel

    Noise Abatement Concept

  • Close up of system on articulating pile gripper

    System deployed around pile under pile gripper

    Noise Abatement Concept

    2014 Demo Panel

  • 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

  • Offshore Demonstration

    The IHC Merwede NMS

  • Three different resonator sizes

    Offshore Demonstration

  • Deployed system in the water Experimental setup

    Offshore Demonstration

  • 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

  • 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

  • 440 kg static load tested Slight plastic deformation afterward

    NEW ACOUSTIC RESONATORS

    Modern Noise Abatement System

  • 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

  • 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

  • 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

  • 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

    Slide Number 1Technology BackgroundBubble ResonanceBubble ResonanceBubble ResonanceEnergy LossesAcoustic DemonstrationValidationValidation & PredictionHelmholtz ResonanceNoise Abatement ConceptNoise Abatement ConceptOffshore DemonstrationOffshore DemonstrationOffshore DemonstrationOffshore DemonstrationOffshore DemonstrationModern Noise Abatement SystemModern Noise Abatement SystemModern Noise Abatement SystemModern Noise Abatement SystemOther ApplicationsSummary