FANS Noise Source Analysis Using Virtual Spherical Waves
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Solution Overview
Problem
Current methods are inadequate for diagnosing noise source strengths on arbitrarily shaped objects using far-field acoustic pressure measurements, as they require numerous measurements and are ill-posed, making traditional near-field acoustic holography (NAH) impractical in hostile environments or when quick estimates are needed.
Innovation Solution
The FANS algorithm uses a superposition of distributed spherical waves to reconstruct acoustic pressure on the source boundary surface by distributing virtual spherical wave sources on an auxiliary surface conformal to the target source, requiring fewer measurements and allowing for quick estimates of noise source strengths in far-field conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If near-field acoustic holography is used to obtain precise acoustic pressure measurements, then measurement precision is improved, but device complexity and measurement cost increase significantly
Solution Approach 1:
The patent introduces virtual spherical wave sources as an intermediary mathematical construct to bridge the gap between far-field measurements and source characterization. These virtual sources serve as a mediator that allows reconstruction of acoustic field information without requiring physical near-field measurement apparatus
Solution Approach 2:
The patent replaces the mechanical near-field measurement system with a mathematical far-field analysis system. Instead of using complex physical measurement devices in the near field, the invention uses spherical wave superposition mathematics applied to simpler far-field microphone measurements
2Measurement precision
If measurement devices are placed near the noise source to obtain accurate data, then measurement precision is improved, but the harmful effect of measurement devices altering the acoustic pressure field increases
Solution Approach 1:
Virtual spherical wave sources act as a mathematical intermediary that eliminates the need for physical measurement devices near the source. The virtual sources are computational constructs that do not physically exist and therefore cannot alter the acoustic field
Solution Approach 2:
The patent creates a mathematical copy of the acoustic field using spherical wave functions. Instead of physically measuring near the source, the system reconstructs the field characteristics through mathematical modeling based on far-field measurements
3Object-generated harmful factors
If far-field measurements are taken to avoid altering the acoustic field, then harmful effects are reduced, but measurement precision and source location accuracy deteriorate
Solution Approach 1:
The patent changes the mathematical parameters used in far-field analysis from plane wave assumptions to spherical wave superposition. This parameter change enables the system to extract precise source location and strength information from far-field measurements by accounting for the spherical geometry of acoustic wave propagation
Solution Approach 2:
The patent adds a mathematical dimension through the introduction of spherical harmonic functions and radial distance parameters. This transforms the far-field measurement data into a multi-dimensional spherical coordinate system that enables precise source localization
4Ease of operation
If beamforming is used for far-field source identification, then directional information is obtained, but source strength distribution on arbitrarily shaped surfaces cannot be identified
Solution Approach 1:
The patent replaces the planar assumption of traditional beamforming with spherical geometry. By using spherical wave functions and distributing virtual sources on a spherical surface, the method naturally adapts to arbitrarily shaped acoustic sources while maintaining mathematical consistency
Solution Approach 2:
The spherical wave superposition method serves multiple functions simultaneously: it provides source location identification, source strength distribution mapping, and works for both near-field and far-field measurements. This universal approach replaces the need for separate specialized methods
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
FANS enables efficient and flexible noise diagnostics by reducing the number of required measurements, providing quick estimates of noise source strengths on arbitrarily shaped objects, even in hostile environments, while maintaining accuracy and portability.
Implementation Method 1
The FANS algorithm uses a superposition of distributed spherical waves to reconstruct acoustic pressure on the source boundary surface
Data Source
AI summary
An algorithm diagnoses the noise source strength distribution on an arbitrarily shaped object based on acoustic pressures measured in the far field, known as FANS. FANS enable one to acquire a quick estimate of the acoustic pressure at locations that are off limit to traditional measurement microphones. Generally, in the method of the present invention, the noise source is modeled in terms a plurality of virtual spherical wave sources distributed on an auxiliary surface conformal to a source boundary from the inside, but not on the source boundary itself. Sound is then measured at a plurality of measurement points external to the source boundary. The sound field is reconstructed on the source boundary surface itself.