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Type: Artigo de periódico
Title: Application of the ultrasonic technique and high-speed filming for the study of the structure of air-water bubbly flows
Author: Carvalho, RDM
Venturini, OJ
Tanahashi, EI
Neves, F
Franca, FA
Abstract: Multiphase flows are very common in industry, oftentimes involving very harsh environments and fluids. Accordingly, there is a need to determine the dispersed phase holdup using noninvasive fast responding techniques; besides, knowledge of the flow structure is essential for the assessment of the transport processes involved. The ultrasonic technique fulfills these requirements and could have the capability to provide the information required. In this paper, the potential of the ultrasonic technique for application to two-phase flows was investigated by checking acoustic attenuation data against experimental data on the void fraction and flow topology of vertical, upward, air-water bubbly flows in the zero to 15% void fraction range. The ultrasonic apparatus consisted of one emitter/receiver transducer and three other receivers at different positions along the pipe circumference; simultaneous high-speed motion pictures of the flow patterns were made at 250 and 1000 fps. The attenuation data for all sensors exhibited a systematic interrelated behavior with void fraction, thereby testifying to the capability of the ultrasonic technique to measure the dispersed phase holdup. From the motion pictures, basic gas phase structures and different flows patterns were identified that corroborated several features of the acoustic attenuation data. Finally, the acoustic wave transit time was also investigated as a function of void fraction. (C) 2009 Elsevier Inc. All rights reserved.
Subject: Ultrasonic technique
High-speed filming
Air-water bubbly flow
Void fraction
Flow patterns
Transit time
Country: EUA
Editor: Elsevier Science Inc
Rights: fechado
Identifier DOI: 10.1016/j.expthermflusci.2009.06.004
Date Issue: 2009
Appears in Collections:Artigos e Materiais de Revistas Científicas - Unicamp

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