Analysis of experimental data obtained at a sounding rocket campaign

Abstract

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.