Phase-Shifting Flow Paths for Fluid-Borne Noise Reduction
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Solution Overview
Problem
Devices such as blowers, fans, and hair dryers generate loud noises that are disruptive and harmful to human ears, necessitating effective noise mitigation solutions.
Innovation Solution
Implementing a noise reducing device with a primary flow path and phase shifting flow paths within a housing to shift acoustic wave phases, creating destructive interference between sound waves in different portions of the fluid flow, thereby reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If noise cancellation devices are added to reduce noise from fluid flow devices, then noise reduction is achieved, but device complexity increases
Solution Approach 1:
The phase shifting flow path is nested within the housing of the fluid flow device, utilizing the existing structural space. The flow path is positioned inside the housing and extends along a portion of the fluid flow path, creating a compact integrated design that reduces noise without adding external complexity
Solution Approach 2:
The phase shifting flow path acts as an intermediary element between the primary fluid flow and the noise cancellation function. It receives fluid from the primary flow path, introduces phase shift to the acoustic waves, and returns the modified fluid to the primary flow path, thereby mediating the noise reduction effect
2Object-affected harmful factors
If phase shifting flow paths are added to create destructive interference, then noise reduction is achieved, but manufacturing complexity increases
Solution Approach 1:
The phase shifting flow path is designed with specific local characteristics including a cross-sectional area that is a fraction of the primary flow path's cross-sectional area, and a length that is a fraction of the primary flow path's length. These localized dimensional specifications make the component manufacturable while achieving the required phase shift effect
Solution Approach 2:
The design specifies particular parameter ranges for the phase shifting flow path dimensions (cross-sectional area as a fraction of primary flow path area, length as a fraction of primary flow path length) to optimize the phase shift effect. These parameter specifications guide manufacturing by defining acceptable ranges rather than requiring precise custom dimensions
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 device effectively reduces noise by causing sound waves to destructively interfere, targeting frequencies most bothersome to the human ear, resulting in a more pleasant sound quality and overall noise reduction.
Implementation Method 1
shift acoustic wave phases in at least a portion of a fluid flow such that the sound waves in that portion destructively interfere with sound waves in another portion of the fluid flow
Implementation Method 2
when two acoustic waves are out of phase such that one wave's pressure peaks align with the other wave's pressure valleys (decreased pressure regions), the result is destructive interference and noise reduction
Data Source
AI summary
An exemplary noise reducing device for reducing the noise of sound waves propagating through a fluid includes a housing; a primary flow path within the housing configured to receive a first portion of the fluid; and at least one phase shifting flow path within the housing configured to receive a second portion of the fluid, wherein the first portion of the fluid flowing through the primary flow path produces a first sound wave, and wherein the second portion of the fluid flowing through the phase shifting flow path produces a second sound wave out of phase relative to the first sound wave at a target frequency, such that the first sound wave destructively interferes with the second sound wave to reduce noise of the first and second sound waves.