Simultaneous measurement method for bubble size and velocity based on light field imaging PTV.

To study the three-dimensional motion characteristics of bubbles in a bubble slurry bed, a simultaneous measurement method for bubble size and velocity based on a light field imaging particle tracking velocimetry (PTV) technology was proposed. A light-field PTV bubble measurement system was constructed, the light-field camera was used to collect two consecutive light field images. After refocusing calculation, image processing and sharpness evaluation, the size and three-dimensional coordinates of the bubbles were calculated combined with the calibration results. The PTV technology was used to calculate the three-dimensional velocity of the bubble, and the simultaneous measurement of bubble size and three-dimensional velocity was completed. The evaluation of the light field PTV system and the measurement of bubble size and three-dimensional velocity were carried out. The results show that the relative error of the diameter measurement is less than 1.60%, the repeatability error of the diameter measurement is less than 2. 48%, and the relative error of the depth position measurement is less than 7.14% . When the air flow increases from 0.1 L/min to 0.5 L/min, the average equivalent diameter of the bubbles increases from 3. 85 mm to 4. 36 mm, and the average bubble velocity increases from 0. 34 m/s to 0. 38 m/s. The light field imaging PTV technology can be used for simultaneous measurement of the bubble size and the three-dimensional velocity. [ABSTRACT FROM AUTHOR]