Volumetric characterization of dispersed two-phase flows by digital image analysis

A digital-based image analysis system has been developed for the experimental determination of size, spatial distribution and two components of velocity for particles suspended in any clear fluid flow. A volumetric measurement directly provides number density and consequently particle flow. A peculiarity of the developed system is its suitability for relatively large particles (some mm in diameter), which can hardly be measured with other systems. Double exposed particle images, in the same frame, provide the starting point for image processing. The system includes a procedure for the classification of the particles in the image, the separation of the partially overlapped particles and the selection of those that are found in the control volume. These parameters serve as a basis for the velocity determination through a particle-tracking algorithm (PTV), which is based on iteratively estimating the match probability as a measure of the likelihood of pairing. The depth of the control volume is obtained with a new technique, based on the loss of focus of the particles in the image, combined by diffuse illumination, provided by twin short pulse argon spark discharge lamps. The system has been extensively checked using calibrated micro-balls and sprays that simulate rain.

[1]  W. Bachalo,et al.  Phase/Doppler Spray Analyzer For Simultaneous Measurements Of Drop Size And Velocity Distributions , 1984 .

[2]  James R. Parker,et al.  Practical Computer Vision Using C , 1993 .

[3]  C. J. Bates,et al.  Particle sizing techniques in multiphase flows: A review , 1990 .

[4]  J. Nogueira,et al.  Local field correction PIV: on the increase of accuracy of digital PIV systems , 1999 .

[5]  Peter John Bryanston-Cross,et al.  Two sub-pixel processing algorithms for high accuracy particle centre estimation in low seeding density particle image velocimetry , 1996 .

[6]  A. Lecuona,et al.  Caracterización de flujos bifásicos dispersos por análisis digital de imágenes , 2000 .

[7]  Z. C. Liu,et al.  A backlighted imaging technique for particle size measurements in two-phase flows , 1998 .

[8]  S. Zaidi.  DIFFICULTIES IN MEASURING LIQUID DROPLET SIZE DISTRIBUTIONS USING LASER DIFFRACTION TECHNIQUE , 1998 .

[9]  Pierre Soille,et al.  Mathematical Morphology and Its Applications to Image Processing , 1994, Computational Imaging and Vision.

[10]  Sang Joon Lee,et al.  A new two-frame particle tracking algorithm using match probability , 1996 .

[11]  Sung Soo Kim,et al.  Drop Sizing and Depth-of-Field Correction in TV Imaging , 1994 .

[12]  Jim Swithenbank,et al.  A Laser Diagnostic Technique for the Measurement of Droplet and Particle Size Distributions , 1976 .

[13]  Antonio Cenedese,et al.  Recognition of partially overlapped particle images using the Kohonen neural network , 1995 .

[14]  Arch C. Luther.  Video camera technology , 1998, Digital audio and video series.

[15]  A. Tonazzini,et al.  Drop size distribution in sprays by image processing , 1990 .

[16]  R. Adrian.  Particle-Imaging Techniques for Experimental Fluid Mechanics , 1991 .

[17]  I. Grant.  Particle image velocimetry: A review , 1997 .