Experimental study on bubble behaviors in microgravity pool boiling

In this paper, the image analysis method is used to study the experimental data of the single bubble subcooled boiling experiment aboard the Chinese recoverable satellite SJ-10. The growth process of single vapor bubble in microgravity is extracted and analyzed. The bubble formation by the pulse excitation, steady growth of the bubble adhering to the excitation point, and its sliding over the heating surface are observed. Among the above three stages, the stage of steady growth of the bubble adhering to the excitation point can be divided into two sub-stages, i.e. expansion and retreat of the bubble base. During the bubble base expansion sub-stage, its radius can be expressed as an exponential function of time. The exponent decreases from 0.42 for the smaller size to 0.28 for the medium one, and finally to 0. The bubble size slightly retraces at the beginning of the bubble base retreat, and then slowly increases again until the subcooled liquid penetrated the bottom of the bubble completely, causing the bubble to detach from the heating surface and then slid on the heating surface under the external disturbance. The results can be used as the basis for the analysis of bubble thermal dynamics in boiling phenomena.