Jornal de termodinâmica e catálise
Acesso livre

Abstrato

The Investigation of the Effect of Reduced and Microgravity Conditions on Single Bubble (Drop) Behavior Fixed on a Solid Surface in a Liquid

Michael Shoikhedbrod

The study of the gas bubble (drop) behavior under reduced gravity and microgravity conditions may be used in the conceptual design of aircraft’s and space based gas-liquid management system. It is very important to consider the changed gravity and microgravity conditions influence on the gas bubble (drop) behavior fixed on the solid surface, as this influence can be more strongly than other external forces action. The main purpose of the present research to investigate the effect of reduced and microgravity conditions on single bubble (drop) behavior, fixed on the solid surface in the liquid. It has been developed a new mathematical techniques to model the behavior of the gas bubbles (drops), fixed on the solid surface in the liquid under reduced and microgravity conditions. These techniques have been used to modelling of the gas bubbles (drops) profiles behavior and to calculation of their common surface energy change under decreased, increased and microgravity conditions. The model has been used also to estimate conditions of bubbles (drops) tear from and fixation on the solid surface in these conditions. The numerical calculations of the developed model permitted to establish that under decreased gravity the gas bubble (drop) is ‘raised’ on the solid surface in the liquid and its common surface energy is free. The gas bubbles with volumes (as example) from 1.9-2.2 cm3 are tore from solid surface and their free energy is transformed to the kinetic energy of bubble jumping from top to the liquid bottom. The gas bubbles with volumes from 2.3-2.8 cm3 were fixed on the solid surface and their free energy was expensed on the gas bubbles oscillations at the solid surface. Under increased gravity conditions the gas bubble (drop) is ‘laid’ on the solid surface in the liquid and the common surface energy is not a free and it is expensed on the bubbles (drops) oscillations at the solid surface.

The theoretical conclusions and numerical calculations of the developed model have been proved on the conducted parabolic aircraft's tests. The tests have proved that the developed model can correctly simulate the gas bubbles and drops profiles behavior, their common surface energy change and estimate conditions of their tear from and fixation on the solid surface in reduced and microgravity conditions. The computer techniques of the model can simulate the bubbles and drops behavior under different external forces influences in microgravity conditions (g=0) when they are considered. Besides, using of the developed model permits to control of the gas bubbles and drops behavior in microgravity by controlled changing of surface tension and cohesive angle (apolar reactives action).