Blower Sound Quality via Irregular Blade Distribution
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Solution Overview
Problem
Rotating machinery, such as fans and turbines, generate annoying noise due to irregular sound frequency spectra, which existing methods only reduce in intensity without transforming the sound quality, leaving discomfort despite noise level reduction.
Innovation Solution
An irregular distribution of blades is determined through a method involving iterative calculations and random configurations to accentuate specific frequencies forming a musical chord, while attenuating others, using physical data and experimental amplitude functions to optimize angular spacings and reduce noise annoyance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the angular spacing between blades is modified to reduce the amplitude of sounds at blade passing frequency, then the noise level is reduced, but the sound remains harsh and tonal, causing continued nuisance
Solution Approach 1:
The patent applies asymmetry by distributing blades irregularly around the rotor circumference rather than using uniform spacing. This asymmetric distribution transforms the harmonic structure of emitted sounds, converting harsh tonal frequencies into a more pleasant spectral composition that resembles musical chords, thereby reducing perceived nuisance while maintaining operational efficiency
Solution Approach 2:
The patent changes the angular position parameters of each blade individually to optimize the frequency spectrum. By adjusting these positional parameters through iterative calculation, the system transforms the acoustic output from harsh tonal sounds to a more pleasant spectral distribution, effectively addressing both noise level and sound quality concerns
2Object-generated harmful factors
If blade distribution is optimized to reduce sound amplitude at fundamental frequencies, then noise intensity is reduced, but the sound quality is not transformed and remains disturbing
Solution Approach 1:
The patent converts the harmful effect of blade passing frequencies into a beneficial outcome by strategically positioning blades to generate a frequency spectrum resembling musical chords. This transformation turns what would normally be disturbing tonal sounds into pleasant acoustic patterns, effectively converting noise harm into a beneficial sound quality improvement
Data Source
Figure 1~3
AI summary
A method for improving the sound quality of a blower (1) by irregularly distributing the rotor (11) blades or stator vanes (12). The distribution of the blades or vanes is determined from randomly generated configurations that meet the physical conditions of the blower and the imposed limits. Within the spectrum of these machine configurations, lines corresponding to a musical chord are identified; these lines are accentuated by reducing the amplitude of the other lines.We then proceed with a selection based on criteria and complete the population of configurations to move to a next step by iteration by applying the same selection criteria to the spectrum of lines of the configurations taken from the first step and those added in addition, so as to make the iteration converge towards optimal configurations from which we choose the one that is physically the most appropriate.