Adjustable Helical Acoustic Resonator for Variable Fan Noise
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Solution Overview
Problem
Existing acoustic resonators are limited in their ability to reduce fan noise across varying fan rotation speeds, as their geometry is fixed and cannot effectively attenuate noise at different acoustic frequencies generated by fans operating at different speeds.
Innovation Solution
An adjustable acoustic resonator with a flexible wall and sliding or rotating sections allows for varying the length between its inlet and outlet, ensuring constant channel length and enabling noise reduction across multiple fan rotation speeds by creating phase opposition between axial and helical acoustic waves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed geometry acoustic resonator is used, then noise attenuation is effective at a specific fan rotation speed, but noise reduction capability is lost when fan rotation speed varies
Solution Approach 1:
The resonator incorporates adjustable components that allow its geometric parameters (such as channel length or cross-sectional area) to be dynamically modified according to the fan rotation speed, enabling the resonator to maintain optimal noise attenuation performance across varying operating conditions
Solution Approach 2:
The resonator design allows for changing its geometric parameters to match different acoustic wavelengths generated at different fan speeds, thereby maintaining effective noise attenuation across a range of rotation speeds
2Adaptability or versatility
If the acoustic resonator length is modified to target different acoustic frequencies, then noise reduction expands to multiple rotation speeds, but device complexity increases
Solution Approach 1:
The resonator is divided into modular sections that can be independently adjusted or configured, allowing the system to achieve multi-frequency noise reduction capability while maintaining manageable structural complexity through standardized modular components
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 solution effectively reduces fan noise across multiple acoustic frequencies by generating destructive interference, providing a more versatile noise attenuation system for electric or hybrid vehicle cooling fans.
Implementation Method 1
Acoustic helical resonator manipulates an existing incident acoustic wave, created by fan flow, to generate a phase shifted acoustic wave. At resonator outlet, the recombination of incident and phase shifted acoustic waves create destructive interferences that significantly reduce overall noise radiation.
Implementation Method 2
Acoustic resonator for attenuating noise in an outlet duct of a fan
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to an acoustic resonator (2) for a fan (1) comprising an annular shape internal volume defining by a housing (25), housing and internal volume are coaxial relative to the longitudinal axle of the acoustic resonator (2), internal volume comprises at least one coaxial helical channel (25), the at least one coaxial channel (25) comprise an inlet and outlet corresponding to inlet and outlet of the acoustic resonator characterized in that the acoustic resonator (2) comprises adjusting means provide for modified the length between inlet and outlet of the acoustic resonator (2) according an acoustic frequency to lower noise.