An analysis of experimental data obtained in a sounding rocket campaign is
presented. Data were obtained in the sounding rocket Rexus-V launch, as part
of a student campaign organized by ESA (European Space Agency). We took
part in the campaign with the project Vib-Bip, which consisted in an experiment
to study two-phase fluids behaviour in microgravity and hipergravity conditions.
The experimental setup contained four test cells with different liquids and gas
fractions, in order to generate bubbles with different characteristics. Two of the
cells contained water and air in different proportions, the third cell contained
silicon oil and air, and the fourth one contained ethanol and air. The test cells
contained different liquids in order to determine the influence of surface tension
and viscosity, and different proportions of liquid and gas in order to determine
the influence of volume fraction in bubble behaviour.
We obtained a high quality video from the rocket launch. The images have
been analyzed in order to determine the acceleration (gravity) dependence of
bubble position and shape. The video reflects both microgravity and
hipergravity phases. The video analysis has allowed us to determine that
bubble height inside the cavity depends directly on the acceleration rate of
change, as well as on the air volume fraction. We have also observed that
eccentricity is higher for lower accelerations. We have determined that bubble
diameters are smaller when the acceleration rate of change is zero. Moreover,
we have observed that bubble equivalent diameter decreases with surface
tension and increases with viscosity, while eccentricity and equivalent volume
increase with surface tension and decrease with viscosity.
