TWO-DIMENTIONAL FLOW CHARACTERISTICS OF BUBBLY COCURRENT FLOW IN A VERTICAL RECTANGULAR CHANNEL

摘要

The authors have developed a new measurement systemrnwhich consisted of an ultrasonic velocity profile monitor and arnpersonal computer in order to clarify its two-dimensional flowrncharacteristics in bubbly flow and to offer a data base tornvalidate numerical codes for two-dimensional two-phase flow.rnIn this paper, the proposed measurement system was applied forrndeveloped bubbly cocurrent flows in a vertical rectangularrnchannel. At first, both bubble and water velocity profiles andrnvoid fraction profiles in the channel were investigatedrnstatistically. Next, turbulence intensity in a continuous liquidrnphase was defined as a standard deviation of velocityrnfluctuation, and the two-phase multiplier profiles of turbulencernintensity in bubbly cocurrent flows were discussed as a ratio ofrnthe standard deviation of flow fluctuation in a cocurrent flow tornthat in a water single phase flow. In addition, the distributionrnparameter and drift velocity used in the drift flux model wererncalculated directly from these profiles.