Математическое моделирование процессов кипения в невесомости

Abstract

By the methods of mathematical modeling with computational experiment, research processes of liquid boiling in complete weightlessness are conducted with the aim to confirm the scientific hypothesis of the existence of non-gravitational mechanisms of a steam bubble separation from the surface of a heater. It is known that in the terrestrial conditions, and in the conditions of reduced intensity of the field of the mass forces, boiling crisis occurs when the intensity of vaporization is so high that the flow of steam impedes the liquid supply to the heater surface. This phenomenon is quantitatively well described by the Kutateladze formula or other formulas that connect critical heat flux with the value of the gravitational acceleration g. The basis of this connection is a Kelvin-Helmholtz instability mechanism (Zuber explanation) within the process of interaction of a vapor domain and a liquid flow, generated by the buoyancy force (the Rayleigh-Taylor instability). In weightlessness conditions Rayleigh-Taylor mechanism of liquid flow formation is absent and for the supply of liquid to the heater surface an inertial motion of liquid, generated by the vapor pressure in the bubble, and pulling the bubble away from the heating surface, becomes responsible. It is shown that in the reduced gravity conditions with a decrease in intensity of the field of the mass forces, the role of inertial forces caused by the vapor pressure of the bubble increases. Confirmation of the hypothesis opens the possibility of realization of bubble boiling condition in complete weightlessness and the possibility of an effective heat exchange devices for the space flight conditions, based on phase transitions, development.