Acoustic Metamaterial Structure for Low-Frequency Noise Attenuation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing noise reduction devices, such as resonator-based and sound-absorbing materials, face challenges in effectively reducing low-frequency noise due to size constraints, durability issues, and increased device volume, particularly in narrow spaces.
Innovation Solution
An acoustic metamaterial structure with a periodic arrangement of unit cells having different cross-sectional areas, which forms an acoustic bandgap to attenuate noise in specific frequency ranges, allowing for flexible installation directions and reduced device size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a resonator-based noise reduction device is used to reduce low frequency noise, then noise reduction performance in low frequency range is improved, but device size increases which cannot be accommodated in narrow spaces
Solution Approach 1:
The noise reduction device is divided into multiple unit cells arranged in series, each unit cell contributing to the overall noise reduction function. This segmentation allows the device to achieve low frequency noise reduction without requiring a single large resonator, instead using multiple smaller units that can be accommodated in narrow spaces.
Solution Approach 2:
The patent transitions from a single large resonator approach to a multi-unit cell series arrangement, utilizing the longitudinal dimension of the flow pipe to accommodate multiple units. This dimensional approach allows noise reduction functionality to be distributed along the flow direction rather than requiring a single large volume component.
2Object-affected harmful factors
If the cross-sectional area of the pipe is changed significantly to improve noise reduction performance, then noise attenuation is improved, but device volume increases
Solution Approach 1:
Instead of uniformly changing the cross-sectional area throughout the entire pipe, the patent applies localized area changes at specific positions through the unit cell structure. Each unit cell has a specific cross-sectional area configuration that provides noise reduction functionality without requiring large volume changes elsewhere in the device.
Solution Approach 2:
The device uses a composite structure combining different cross-sectional area configurations within unit cells arranged in series. This composite approach allows the device to achieve noise reduction performance through the combination of multiple unit cells with different geometric characteristics rather than relying on a single large volume change.
3Object-affected harmful factors
If sound-absorbing material is used to reduce high frequency noise, then high frequency noise reduction is improved, but durability decreases due to vulnerability to moisture or heat stress
Solution Approach 1:
The patent replaces sound-absorbing materials with a mechanical noise reduction mechanism based on impedance mismatch and reflection through geometric shape changes in the unit cells. This substitution eliminates the durability issues associated with sound-absorbing materials while maintaining noise reduction functionality through purely structural means.
Solution Approach 2:
The device achieves noise reduction by changing geometric parameters (cross-sectional area, length) of the unit cells rather than relying on material properties. This parameter-based approach provides superior durability since the geometric structure is resistant to moisture and heat stress, unlike sound-absorbing materials that degrade under environmental conditions.
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 acoustic metamaterial structure effectively attenuates noise over a broad range of frequencies by creating a wide acoustic bandgap, improving compatibility and reducing the size and weight of noise attenuation devices.
Implementation Method 1
the acoustic metamaterial structure reduces noise in a specific frequency range through formation of an acoustic bandgap, the specific frequency range being determined by a periodic structure formed by an array of the first space and the second space
Data Source
AI summary
Disclosed herein is an acoustic metamaterial structure which can effectively reduce noise in a specific frequency range through formation of an acoustic bandgap, wherein the specific frequency range is determined by a periodic structure formed by an array of multiple unit cells. The acoustic metamaterial structure includes multiple first unit cells each including a first space having a first cross-sectional area and a second space disposed downstream of the first space in a flow direction of fluid to communicate with the first space, the second space having a second cross-sectional area larger than the first cross-sectional area, wherein the acoustic metamaterial structure reduces noise in a specific frequency range through formation of an acoustic bandgap, the specific frequency range being determined by a periodic structure formed by an array of the first space and the second space.