Hydrodynamics of a two-phase upward flow during boiling at distributed heating centers

In this paper, the mechanics and hydrodynamics of a two-phase boiling flow were investigated, in which the increase in the vapor content in the flow occurs discretely at local vaporization centers distributed uniformly along the length of a vertical channel (pipe). A stand was developed for conducting a model experiment and a method for measuring the velocity of vapor bubbles in a channel based on dynamic light scattering at gas-liquid interfaces. Experimental studies were conducted and data were obtained showing significant differences in the mechanics of two-phase flow motion during discrete and continuous vaporization. The experimental data show a stepwise dependence when changing the parameters during motion between heat sources distributed along the length of the channel. These experiments were approximated using the Heaviside function, which makes it possible to obtain the distribution of parameters along the length and by the amount of vapor in the flow. Energy dependences are obtained based on the principle of least action taking into account the stepwise nature of the change and it is shown that with a change in the intensity of steam generation, the step function degenerates into a smooth one, due to the predominance of the potential energy of hydrostatic pressure. The patterns of change in hydraulic resistance from the dimensional change in the diameter of the channel (pipe) are shown. A topical issue in the work is also the study of changes in flow parameters between the motion sections and in the steam generation sections. From the point of view of practical application, the study of discrete steam generation on distributed heating centers is relevant for immersion cooling systems of microelectronics and new generations of steam generators.