US4866639A
Expired / Lapsed
US
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Method and apparatus for determining the direction of motion in multiple exposure velocimetry
Assignee: University of Illinois at Urbana-Champaign
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Filing: 1987-03-09
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Granted: 1989-09-12
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Expires: 2007-03-09
Abstract
Abstract The present invention is in the context of the measurement of velocity fields of fluid flows containing many small scattering sites, which exist either in the form of particles or optically activated, discrete fluid volumes. The invention is directed to a method and apparatus for resolving ambiguity with respect to the direction of displacement of particle images recorded by multiple exposures on film or videographic media. The invention enables the elimination of directional ambiguity by means of shifting the image field between exposures by an amount that is greater than any negative displacement occurring in the image field. In this way, all recorded displacements are positive, and negative displacements are obtained from the measurements by mathematically subtracting the artificial shift after the measurements.
Inventors
- 👤 Ronald J. Adrian
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 05:42
CPC Classifications
G; G01; G01P; G01P13/00; G01P13/02; G01P13/04; G01P13/045; G01P5/00; G01P5/001
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
125 words
In a velocimetry system in which photographic images, involving first and subsequent exposures, are created by accurately times pulses of light from a light source, and multiple particle images displaced by the motion of a fluid are recorded, such that the fluid velocity is inferred from the displacement of the image field between exposure, the improvement which comprises: means for determining unambiguously the direction of displacement, and hence velocity in said system, said means including means for shifting successive particle images of each scattering site with respect to the first image so that all image displacements are positive even through physical displacements of the scatterers may be negative, said means for shifting being operative during the photographic process between the first exposure and subsequent exposures.
Claim 2
Dependent Claim
125 words
In a velocimetry system in which photographic images, involving first and subsequent exposures, are created by accurately times pulses of light from a light source, and multiple particle images displaced by the motion of a fluid are recorded, such that the fluid velocity is inferred from the displacement of the image field between exposure, the improvement which comprises: means for determining unambiguously the direction of displacement, and hence velocity in said system, said means including means for shifting successive particle images of each scattering site with respect to the first image so that all image displacements are positive even through physical displacements of the scatterers may be negative, said means for shifting being operative during the photographic process between the first exposure and subsequent exposures.
Claim 3
Dependent Claim
18 words
A system as defined in claim 1, in which said means for image shifting comprises a rotating mirror.
Claim 4
Dependent Claim
40 words
A system as defined in claim 2, in which second images are displaced in the image plane by a constant amount X s and subsequent images are shifted by amounts proportional to the time lapse since the first image exposure.
Claim 5
Dependent Claim
100 words
In a velocimetry method in which images are created by accurately timed pulses of light from a light source, and multiple particle images displaced by the motion of a fluid are recorded, such that the fluid velocity is inferred from the displacement of the image field between exposures, the improvement which comprises: the step of determining unambiguously the direction of displacement, and hence velocity, in such system, said step including shifting successive images of each scattering site with respect to the first image so that all image displacements are positive even though physical displacements of the scatterers may be negative.
Claim 6
Dependent Claim
100 words
In a velocimetry method in which images are created by accurately timed pulses of light from a light source, and multiple particle images displaced by the motion of a fluid are recorded, such that the fluid velocity is inferred from the displacement of the image field between exposures, the improvement which comprises: the step of determining unambiguously the direction of displacement, and hence velocity, in such system, said step including shifting successive images of each scattering site with respect to the first image so that all image displacements are positive even though physical displacements of the scatterers may be negative.
Claim 7
Dependent Claim
25 words
A method as defined in claim 4 in which said step is carried out during the photographic process between the first exposure and subsequent exposures.
Claim 8
Dependent Claim
42 words
A method as defined in claim 5, in which second images are displaced in the image plane by a constant amount of X s , and subsequent images are shifted by amounts proportional to the time lapse since the first image exposure.
Claim 9
Dependent Claim
96 words
A velocimetry system for measuring fluid velocity, such system comprising: a light source; means for recording multiple particle images displaced by the motion of the fluid, said images being created by accurately timed pulses of light from said light source, such that fluid velocity is inferred from the displacement of the image field between exposures, and means for determining unambiguously the direction of displacement, said means including means for shifting successive images so that all image displacements are positive, said means for shifting being operative during the photographic process between the first exposure and subsequent exposures.
Claim 10
Dependent Claim
96 words
A velocimetry system for measuring fluid velocity, such system comprising: a light source; means for recording multiple particle images displaced by the motion of the fluid, said images being created by accurately timed pulses of light from said light source, such that fluid velocity is inferred from the displacement of the image field between exposures, and means for determining unambiguously the direction of displacement, said means including means for shifting successive images so that all image displacements are positive, said means for shifting being operative during the photographic process between the first exposure and subsequent exposures.
Claim 11
Dependent Claim
40 words
A system as defined in claim 7 in which all second images are displaced in the image plane by a constant amount Xs and subsequent images are shifted by amounts proportional to the time lapse since the first image exposure.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-09-11 | 1993-03-13 | 1993-09-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-09-11 | 1997-03-13 | 1997-09-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-09-11 | 2001-03-13 | 2001-09-12 | $7700.00 | Window Closed / Lapsed |