Bubble Behavior Studies For Natural & Forced Circulation Conditions

In this thesis, the study on bubble behavior was carried out under subcooled boiling condition. During the experimentation de-ionized water was used as working fluid flowing through an annular channel. Photographic method of experimental observations was utilized both for natural and forced circulation flows. Bubble behavior was compared for each type of flow under conditions of experiments.For a single bubble growth case, the results show that sliding bubbles growth occur according to the Mihic function, which belong to thermal phase whereas the growth at nucleation sites belong to the inertial phase.Theoretical and experimental analysis proved that the bubble rising velocity is in proportion to bubble diameter's square root. For the resistance coefficient calculations, two correlations were developed for natural and forced circulation flows. It was concluded that any one of these can be utilized for both flow types with considerable accuracy. The main factors which influence bubble shape are viscosity and surface tension. As the viscosity and surface tension decreases, the bubble distortion becomes high.In the study of multiple bubbles behavior, vertical aggregation was the main research content. In aggregation process during experiments, a departing phase is observed after tumbling phase, which is different from Fortes chart.