Adjustable Resonator Assembly for Passive Acoustic Emission Reduction
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Solution Overview
Problem
Existing airflow systems, such as fans and vehicle exhausts, produce undesirable acoustic emissions that increase with airflow, and current solutions like active attenuation systems are costly and require power, while passive solutions like acoustic foam are ineffective at low frequencies and bulky.
Innovation Solution
An adjustable resonator assembly using a Helmholtz chamber with a spring-biased mechanism that passively adjusts the neck area of the resonator cavity to match the changing acoustic frequency, eliminating the need for active signal processing by leveraging airflow to modify the resonator's dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If active attenuation systems are used to reduce acoustic emissions, then acoustic reduction effectiveness is improved, but system cost and power consumption increase
Solution Approach 1:
The system uses the airflow itself to drive the adjustment mechanism. The drag force from the gas flow automatically moves the resonator adjustment structure to modify the neck area, eliminating the need for external power sources or active control systems while maintaining adaptive acoustic reduction
Solution Approach 2:
The patent replaces electronic active attenuation systems with a passive mechanical system that uses aerodynamic drag forces to adjust the resonator parameters, substituting complex electronic control with simple mechanical response to airflow
2Object-affected harmful factors
If acoustic foam is used to absorb acoustic emissions, then high frequency attenuation is improved, but low frequency dampening and space efficiency worsen
Solution Approach 1:
The resonator system is dynamically adjustable through airflow-driven movement of the adjustment structure, allowing the neck area to change with flow conditions and acoustic frequency variations, enabling the same device to effectively cover a wide frequency range including low frequencies that static foam cannot address
Solution Approach 2:
The system changes the physical parameters of the resonator (neck area) in response to varying acoustic conditions and airflow rates, allowing adaptation across different frequency ranges rather than being fixed for a single frequency band
3Object-affected harmful factors
If the neck area of the resonator is increased to reduce acoustic emissions, then acoustic attenuation is improved, but the device complexity and adjustment mechanism complexity increase
Solution Approach 1:
The airflow automatically adjusts the resonator parameters through drag forces acting on the adjustment structure, eliminating the need for complex external control mechanisms while achieving the required acoustic attenuation
Solution Approach 2:
The system uses pneumatic forces (drag from gas flow) to directly actuate the mechanical adjustment of the resonator, converting airflow energy into mechanical adjustment without requiring additional actuators or control systems
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
Effectively reduces acoustic emissions by dynamically matching the resonant frequency of the resonator with the peak acoustic frequency of the airflow source, providing a cost-effective and power-free solution that is not limited by frequency range.
Implementation Method 1
The resonator adjustment structure can be biased using a spring having a preselected spring constant whereby to provide a spring compression force equal to a drag force of the resonator adjustment structure when exposed to the flow of the gaseous material
Implementation Method 2
In the second position, the resonator cavity has a selected neck area, whereby to cause the resonator cavity to act as a Helmholtz chamber
Implementation Method 3
Effectively reduces acoustic emissions by dynamically matching the resonant frequency of the resonator with the peak acoustic frequency of the airflow source
Implementation Method 4
The bias mechanism can be a spring with a preselected spring constant
Implementation Method 5
provide a spring compression force equal to a drag force of the resonator adjustment structure when exposed to the flow of the gaseous material
Data Source
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AI summary
An adjustable resonator assembly, comprising a resonator cavity having a neck area with a neck opening configurable to be in fluid communication with a conduit through which a gaseous material can flow, a resonator adjustment structure configured to move from a first position in which the structure closes the neck area when flow of the gaseous material is absent to a second position in which the structure opens the neck area by a predetermined degree in presence of a flow of the gaseous material and a bias mechanism configured to exert a force onto the resonator adjustment structure so as to move the resonator adjustment structure to the first position.