Construção e análise da técnica de sensores duplos de condutividade para a obtenção da velocidade de bolhas usando filmagem

Abstract

This paper aims to describe the construction of a double conductivity sensor, also called electroresistivity sensor and measure the accuracy of electroresistivity technique in determining the speed of the rise of bubbles formed in two-phase flow of water and air, to perform a comparative analysis with the results obtained with the method of digital image correlation. For this ten replicates of each volume of 1, 2, 3, 4 and 5 milliliters (ml) of air bubbles were taken to calculate the speed of ascent in a mixture of water and sodium acetate. All the experimental apparatus needed in the electroresistivity sensors technique was mounted and a commercial camera was placed in front to film the process. Thus, we obtained results for the electroresistivity sensors technique and images were extracted by videos recorded by camcorder which were used for applying the digital image correlation method. The results of both techniques were tabulated and treated statistically, ie an uncertainty analysis was performed, using the concepts of the Student-t distribution. This comparison showed large discrepancy of values due to measurement errors inherent in the process. The larger bubbles showed the most discrepant results except volumes 1 and 2 ml where the error intervals intercepted up.