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ENCIT 2020
18th Brazilian Congress of Thermal Sciences and Engineering
EXPERIMENTAL CHARACTERIZATION OF THE FLOW STRUCTURE IN ACCELERATED BUBBLY FLOWS
Submission Author:
Andreza Ribeiro , SC
Co-Authors:
Rafael Franklin Lazaro de Cerqueira, Emilio Paladino
Presenter: Andreza Ribeiro
doi://10.26678/ABCM.ENCIT2020.CIT20-0673
Abstract
Accelerated bubbly flows have a broad application in various engineering fields. Several authors analyzed the flow and turbulence structure in vertical bubbly pipe flows. However, only a few studies focused on the flow structure in accelerated flows as encountered in flow constrictions, as contractions or bends, specially using the PIV technique which allows for the measurement of the detail of the flow structure. In this work, the flow structure in accelerated vertical air-water flows through convergent-divergent duct was investigated. The liquid phase velocity was measured by the Particle Image Velocimetry technique, using fluorescent tracer particles (PIV/LIF). A Particle Tracking Velocimetry (PTV) technique was used to obtain the bubble size and velocity distribution. In order to overcome the issues related to the presence of bubbles in the PIV measurements of the liquid phase velocity, a technique was employed to remove the dispersed gas phase contribution in the averaged liquid velocity results. The PIV and the PTV methods were validated through a series of gas-liquid vertical bubbly at the inlet section, confirming the reliability of the experimental techniques. The results for the liquid velocity fields in convergent-divergent duct show that the flow structure in completely modified by the presence ob bubbles, even in very low volume fractions, specially, for low liquid superficial velocities.
Keywords
Accelerated Flow, bubbly flow, PIV, PTV
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