IMAGE PROCESSING OF BUBBLY FLOW IN A RECTANGULAR CHANNEL

摘要

This paper presents a new image processing method for quantifying bubbly flow parameters in a vertical rectangular channel. Both the outline and the inner edge of a bubble are extracted from the gray-scale image for the reconstruction of the overlapping bubbles. The reconstructed bubble preserves most of the shape and size information of the original image compared to the simple ellipse fitting method found in literature. Therefore the method could result in a more accurate measurement of the bubbly flow. A control window is introduced to obtain various time- and space-averaged data using the information of the reconstructed bubbles. Continuous distributions of interfacial area concentration, void fraction, Sauter mean diameter along the test channel are obtained from the images captured by five high speed cameras.