In order to study the condensation morphology characteristics and kinetic parameters of steam jet bubbles

visualization experiments are carried out under conditions with steam mass flow flux of 8.34～50.13 kg/(m~2·s) and water temperature of 40～80 ℃. According to the characteristics of the vapor-liquid interface

three typical condensation patterns are defined: intermittent oscillatory bubble regime

smooth grown detached bubble regime and rough grown detached bubble regime. The analysis on bubble dynamic behavior shows that

the maximum bubble radius increases at first and then decreases with the increase of steam mass flux when the water temperature is constant

because the condensation flow pattern changes from smooth grown detached bubble regime to rough grown detached bubble regime. The maximum bubble radius corresponding to these two flow patterns transitions is called the threshold radius. The threshold radius is determined by surface tension

buoyancy force

viscous force and condensation force

and is independent of steam inertia force. Based on the experimental results

a threshold bubble radius prediction model is presented

and the model can well predict the bubble radius of different water temperature thresholds under the experimental working conditions.