Granular Noise Reduction Module for Underwater Low-Frequency Attenuation
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Solution Overview
Problem
Current methods for reducing underwater noise during offshore wind turbine pile-driving, such as hydro-sound-dampers and bubble curtains, are ineffective in reducing low-frequency noise and result in increased carbon emissions and energy consumption.
Innovation Solution
A manufacturing method for a noise reduction module comprising a sound-absorbing layer made from materials like mica powder, alumina, zinc oxide, and barium sulfate, encapsulated in a rubber and/or polyurethane layer, with optional reflective and counterweight layers to enhance noise reduction and buoyancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If hydro-sound-dampers with rigid foam material are used, then noise reduction is achieved, but the noise reduction effect is negatively affected because the hole size is smaller than the main wavelength of pile-driving noise
Solution Approach 1:
The patent changes the physical parameters of the sound-absorbing material by using granular materials with specific particle size ranges (5-20mm, 20-50mm, or 50-100mm) instead of rigid foam with fixed small holes. This parameter change allows the material to effectively absorb low-frequency noise wavelengths that were previously inaccessible to conventional rigid foam structures.
Solution Approach 2:
The patent employs composite sound-absorbing materials consisting of multiple types of granular materials (such as rock wool, glass wool, mineral wool, expanded perlite, or expanded vermiculite) with different particle sizes and acoustic properties. This composite approach enhances the overall noise reduction effectiveness across different frequency ranges, particularly for low-frequency pile-driving noise.
2Object-affected harmful factors
If bubble curtains are used, then noise reduction is achieved, but carbon dioxide emissions and energy consumption increase due to diesel generators and engineering ships
Solution Approach 1:
The sound-absorbing screen is designed as a passive noise reduction system that does not require external energy sources, diesel generators, or continuous operational support. The screen structure with granular sound-absorbing materials provides autonomous noise reduction functionality, eliminating the need for energy-consuming equipment and associated carbon emissions.
Solution Approach 2:
The patent extracts and eliminates the energy-consuming components (diesel generators, pumping systems, engineering ships) from the noise reduction process. By using a static sound-absorbing screen with granular materials, the system removes the need for continuous operational energy input while maintaining effective noise reduction.
3Object-affected harmful factors
If multiple layers of bubble curtains are added, then noise reduction effect is improved, but deployment complexity and energy consumption increase
Solution Approach 1:
The sound-absorbing screen is divided into multiple segments or panels that can be independently assembled and deployed. Each segment contains sound-absorbing materials and can be installed separately, simplifying the overall deployment process compared to multiple layers of bubble curtains that require coordinated pumping and positioning operations.
Solution Approach 2:
The patent uses flexible sound-absorbing screen structures that can be easily deployed and positioned in the water environment. These flexible structures eliminate the need for complex pumping and positioning systems required for bubble curtains, reducing both deployment complexity and operational energy requirements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The noise reduction module effectively absorbs low-frequency sound wave energy, achieving a noise reduction effect of at least −15 dB, and can be easily assembled and reused, reducing environmental impact and improving construction efficiency.
Implementation Method 1
The sound-absorbing layer is used to absorb the incoming sound wave energy
Implementation Method 2
the reflective layer reflects the incoming sound wave energy
Data Source
AI summary
A manufacturing method of a noise reduction module that is used underwater to attenuate low-frequency noise comprises steps of substrate preparation, functional layer fabrication, and encapsulation. The steps are performed by substrate preparation of functional layers of rubber and/or polyurethane, mixing sound-absorbing materials in the substrate material to constitute the sound-absorbing layer, and constituting the encapsulation layer by the substrate material, externally encapsulating the sound-absorbing layer by the encapsulation layer, in order to make into the noise reduction module in a modular structure, which can absorb the incoming sound wave energy by the sound-absorbing layer. The noise reduction screen can be composed of a plurality of the noise reduction modules.