Measurements of velocity field and diameter distribution of particles in multiphase flow based on trajectory imaging

The aim of the present study is to develop an efficient image processing approach and defocus correction model to obtain the particle velocities and diameter distributions from a single-frame & single-exposure image (SFSEI). The image processing approach extracts a particle trajectory to analyse the velocity and diameter via the image segmentation and edge detection. With consideration of the deviations caused by defocused images, a correction model was developed based on the relationships between the grey gradient and defocus distance. This method with the correction model was validated in a free-falling particle experiment. The average deviation of particle velocity between measured values and numerical solutions is 6.1%, and the correction model reduces the diameter deviation from 54% to 27%. The particle velocity fields were also investigated in the gas-liquid-solid flow at a horizontal pipe.