STUDIES ON 2-PHASE CROSS FLOW .3. CHARACTERISTICS OF UNSTEADY-FLOW BEHAVIOR

Basic characteristics in a two-phase wake flow, in particular, fluctuations of bubble number density, were investigated experimentally using mainly flat plates. New measuring procedures of the periodicity of the bubble number density and of the spatial distribution of the phase-averaged void fraction were developed. The experimental results indicated that two kinds of flow patterns appeared alternatively in the wake. Moreover, it was confirmed that one of them corresponded to the Karman vortex type in a single-phase flow and the other was similar to the twin eddies type which was observed under the low Reynolds number (Re less than 10**2) in the flow. The alternation process of the flow patterns depended on the shape of obstacles in the cross flow. In case of a cylinder, numbers of the Karman vortices formed continuously were very few.