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US 5,491,642 AGranted
CCD based particle image direction and zero velocity resolver
AssigneeUnited Technologies Corporation
InventorsDean C. Wormell, Fred R. Huettig, Andrew J. Jankevics, Michael Winter, James L. Sopchak
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Abstract
A PIV system provides a bias velocity component to each flow field speckle pattern recorded on a video array by rastering each corresponding recorded electrical image pattern by a select number of raster lines in the time interval prior to recording a succeeding speckle pattern image, thereby providing a calibrated spatial offset between recorded images.
Claims13
Apparatus for reporting the magnitude and direction of fluid velocities in a flowing fluid having light reflective particles disposed therein, comprising:
- light source means, for providing light pulses to periodically illuminate the light reflective particles at the pulse repetition rate of a gate signal presented thereto, to provide an optical speckle pattern image representative of the spatial position of the particles in the flowing fluid in each of two successive time intervals which are spaced in time by an interpulse period;
- video recording means, having an array with a receiving surface for receiving each said optical speckle pattern image at a point of incidence thereon and for recording each received optical speckle pattern image as a corresponding electrical signal pattern, said video recording means shifting each said electrical signal pattern in said interpulse period from said point of incidence to a second position on said array major surface which is displaced from said point of incidence by a spatial increment whose value is determined by the magnitude of a bias displacement signal presented thereto;
- and
- signal processor means, responsive to said light source means and to said recording means, and having keyboard means responsive to operator control, for providing said gate signal to said light source means and for providing said bias displacement signal to said video recording means, respectively, at a pulse repetition rate and bias magnitude selected by an operator to shift said recorded electrical signal pattern by a known velocity bias value in said interpulse period.
1 more element
Apparatus, for reporting the magnitude and direction of fluid velocities in a fluid flow having particles disposed therein, comprising:
- light source means, for illuminating a test region of the fluid flow with pulsed light at a pulse repetition rate controlled by a gate signal presented thereto, to create optical images of the speckle pattern of the light reflected from the particles in each of two successive time intervals spaced in time by an interpulse period, each optical image indicating the spatial position of the particles in the flow in the associated time interval and successive optical images indicating the time lapsed displacement of the particles in the flow;
- video recording means, having aperture means for receiving each said optical image at a point of incidence on a receiving surface of an array therein and for recording the speckle pattern of each optical image as a corresponding electrical signal pattern and, in response to a bias signal presented thereto, for shifting the position of each recorded electrical signal pattern from said point of incidence to a displaced position offset therefrom by a distance determined by the magnitude of said bias signal;
- and
- signal processor means, having keyboard means responsive to operator control for providing said gate signal to said light source means and for providing said bias signal to said video recording means, each respectively at a pulse repetition rate and a bias magnitude selected by an operator, and having memory means for storing signals representative of a vector autocorrellation algorithm, said processor means being responsive to each said recorded electrical signal pattern for applying said autocorrellation algorithm to successive ones of said recorded electrical signal patterns to provide a calculated flow direction and a calculated flow velocity magnitude in dependence on the time lapsed displacement value of the particles in successive optical images.
1 more element
Dependencies are inferred from the claim text.