A simple 3D reconstruction algorithm based on laser scanning: Research on flow characteristics of bubbles rising vertically in liquid phase

Bubbly flow is frequently observed in chemical industries such as reactors and steam boilers, where flow pa-rameters of bubble velocity, size, and void fraction are required to guide process safety. In this paper, a laser scanning-based three-dimensional reconstruction algorithm is introduced to achieve simple and effective mea-surements in vertical bubbly flow. A series of slice images are captured by a high-speed camera, and a modified two-dimensional cross-correlation algorithm is proposed to achieve bubble extraction and matching. Based on the reconstructed flow structures of bubbly flow, bubble velocities and their distribution in different scanning cycles are measured. Statistically, bubble sizes are mainly concentrated within 1.8-2.2 mm. The void fractions are calculated for various gas flow rates with relative errors primarily within +/- 10%. The relative errors of the average void fraction are less than 8% by comparing the experimental and theoretical results, indicating a higher reconstruction precision.

Automated summary

This paper introduces a laser scanning-based three-dimensional reconstruction algorithm for simple and effective measurements in vertical bubbly flow. It captures a series of slice images using a high-speed camera and proposes a modified two-dimensional cross-correlation algorithm for bubble extraction and matching. Based on the reconstructed flow structures, bubble velocities and their distribution in different scanning cycles are measured. Statistically, bubble sizes are mainly concentrated within 1.8-2.2 mm. The void fractions are calculated for various gas flow rates with relative errors primarily within +/- 10%, and the average void fraction has a relative error of less than 8%, indicating higher reconstruction precision.