Master's Theses

Date of Award

2012

Document Type

Thesis

Department

Chemical Engineering

Keywords

Airbubble, Injection, in Laminar/Lurbulent Flow

Abstract

Injection of bubbles into a vertical upward flow of water in an annular flow channel was studied experimentally under laminar and turbulent conditions. In order to measure the size and shape of the bubbles, a flow visualization system was set up in a vertical test section with a high speed video camera. A PIV measurement technique was also used to determine laminar and turbulent velocity profiles in the liquid stream. In this study, an efficient image processing methodology was used to obtain the velocity profiles, bubble size, shapes and trajectory at different Reynolds numbers. The measured velocity profiles matched theoretical profiles for single-phase laminar and turbulent flows in an annular channel. The experimental results indicate that air bubble injection from an inner tube into the liquid stream causes large increase in the streamwise and spanwise velocity fluctuations near the inner tube wall for both laminar and turbulent liquid flows. The bubble size, shape, and trajectory data were also obtained for both laminar and turbulent flows. For laminar flow, bubble coalescence was observed to occur. The ensemble-average bubbles trajectory data showed that the bubble follow a similar trajectory in the annular flow channel following their departure from the injection hole

 
 

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