Experimental study on continuous spectrum bubble generator with a new overlapping bubbles image processing technique

Abstract

• The CSBG, which can produce bubbles with continuous sizes is developed. • Experimental results show that CSBG can generate bubbles of continuous sizes. • Overlapping bubbles processing technique (OBPT) based on CPD & FSAC is proposed. • Accuracy of OBPT exceeds 95% with a sub-second response time per hundred bubbles. The parameter of bubble size is of great significance to the bubbly flow. In this paper, the Continuous Spectrum Bubble Generator (CSBG), consisting of a sparger and impeller, was developed to realize the continuous control of bubble sizes. By introducing a new variable, rotation rate of the impeller, bubble size and gas superficial velocity are successfully decoupled. Experimental results show that bubble sizes continuously drops from 3 to 1 mm, without changing gas superficial velocity. Also, the spectrum of bubble size can be expanded by increasing or decreasing mass flow rates. To detect the overlapping bubbles, a new overlapping bubbles processing technique based on fast segmented arcs clustering was proposed. It’s efficient to cluster the segmented arcs through detecting the Major and Pair arcs and connecting the Multi-segment arcs through concave points connection methods. Test results show that the accuracies of mean diameter exceed 95% with sub-second response time per hundred bubbles.