Micro-perforated plate acoustic absorber with coiled propagation passage
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Solution Overview
Problem
Low-frequency acoustic wave attenuation and absorption are challenging due to size limitations of acoustic structures, requiring innovative solutions for effective broadband acoustic wave absorption.
Innovation Solution
An acoustic absorber comprising a micro-perforated plate, a cavity, and a main acoustic propagation passage with acoustic filters of varying cut-off frequencies, where acoustic waves pass through the micro-perforated plate, enter the cavity, and propagate through a slender, curved passage with filters arranged from high to low cut-off frequencies, achieving broadband absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional acoustic structures are used for low-frequency acoustic wave attenuation, then acoustic absorption can be achieved, but the structure size becomes excessively large
Solution Approach 1:
The acoustic propagation path is segmented into multiple sections with different acoustic impedance characteristics. The passage includes a first section with larger cross-sectional area and a second section with smaller cross-sectional area, creating distinct acoustic zones that work together to enhance low-frequency absorption while reducing overall structure volume.
Solution Approach 2:
The invention transitions from traditional planar acoustic structures to a three-dimensional coiled or folded passage configuration. By utilizing vertical and horizontal spatial dimensions through coiling or folding the acoustic passage, the effective acoustic path length is extended without increasing the footprint area, thereby reducing the overall structure volume while maintaining low-frequency absorption performance.
2Adaptability or versatility
If broadband acoustic wave absorption is achieved through multiple acoustic filters, then frequency range coverage is improved, but device complexity increases
Solution Approach 1:
The broadband absorption is achieved by segmenting the acoustic spectrum into different frequency bands using multiple acoustic filters with distinct cut-off frequencies. Each filter targets a specific frequency range, and their cascaded arrangement creates comprehensive broadband coverage while maintaining individual filter simplicity.
Solution Approach 2:
The invention varies the cut-off frequency parameter of successive acoustic filters to cover different frequency ranges. By systematically changing this key parameter across multiple filters arranged in sequence, broadband absorption is achieved without requiring complex individual filter designs, thus managing device complexity through parameter variation rather than structural complexity.
3Reliability
If a slender and curved main acoustic propagation passage is used, then phase delay variation is improved, but manufacturing difficulty increases
Solution Approach 1:
The acoustic propagation passage is designed with curved or coiled geometry instead of straight linear paths. This curvature enables the passage to fit within compact spaces while providing extended acoustic path lengths necessary for phase delay control. The curved configuration allows phase delay variation across different frequencies without requiring excessively long straight passages.
Solution Approach 2:
The coiled or folded passage configuration effectively nests the acoustic path within a compact volume. By folding the passage back on itself or coiling it in a spiral pattern, the design achieves long acoustic path lengths within small physical dimensions, facilitating phase delay control while maintaining manufacturability through standard fabrication techniques.
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
This configuration provides effective broadband acoustic wave absorption by varying phase delay and ultra-thin structure, enhancing acoustic energy absorption and reflection.
Implementation Method 1
a micro-perforated plate... diameters of the perforations on the micro-perforated plate are not bigger than 0.5mm... acoustic waves pass through the micro-perforated plate
Implementation Method 2
a cavity behind the micro-perforated plate... The cavity behind the micro-perforated plate is arranged between the micro-perforated plate and the main acoustic propagation passage... acoustic waves in the cavity will propagate along the direction from the inlet to the outlet
Implementation Method 3
a set of acoustic filters arranged along the main acoustic propagation passage... these acoustic filters have different cut-off frequencies and are arranged in the order of cut-off frequency from high to low... at each acoustic filter arranged along the main acoustic propagation passage, acoustic waves are divided into two parts, where one part goes into the acoustic filter and is absorbed or reflected
Data Source
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AI summary
The type of acoustic absorber comprises a micro-perforated plate, a cavity behind the micro-perforated plate, a slender and curved main acoustic propagation passage communicating with the cavity, and a set of acoustic filters arranged along the main acoustic propagation passage. These acoustic filters have different cut-off frequencies and are arranged in the order of the cutoff frequencies from high to low from the open end to the closed end of the main acoustic propagation passage. The acoustic filter comprises a section of the main acoustic propagation passage and at least one cavity communicating with the main acoustic propagation passage. The type of acoustic absorber is characterized by adopting a main acoustic propagation passage to provide different phase delay for a micro-perforated plate to realize that a micro-perforated plate effectively absorbs broadband acoustic waves, and by combing the close arrangement of main acoustic propagation passage to achieve the ultra-thin structure.