Phenomenological Investigation of Gas-Liquid Flows

摘要

An average bubble number density transport equationfor multidimensional two phase flow was tested usingCFD to predict the transitional flow regime of capped andspherical bubbly flow mixtures.The use of Yao and Morel expression for bubblecoalescence and breakage, plus the incorporation ofTomiyama’s lift co-efficient produced sufficientlyconvincing results for capturing the ‘wall peaking’ voidfraction profile of bubbly flow regimes.Prediction of transitional flow regimes were lesssuccessful, though a simultaneous combination of wallpeaking and core peaking void fraction profiles wereproduced as expected. The high incidence of air voidfraction near the exit of the cylindrical test section showpossible deficiencies in current coalescence mechanismsfor replicating the complex interaction of capped bubblesand bubbly flow mixtures. Work is currently beingcarried out to possibly incorporate a two groupcapped/spherical bubble model as ventured by Hibiki &Ishii.