Effect of Vibration on Transport Experiments - Model Experiments during Parabolic Flights

Kurzfassung

Diffusion and convection are the main physical processes in crystal growth and metallurgy. On ground, the measured diffusion coefficients of liquids are often enlarged due to the additional mass transport of the natural convection especially at high temperatures. In microgravity, g-jitter and residual acceleration can easily disturb the measurement. The influence of vibrations on liquid transport experiments was investigated quantitatively in a model heat transport experiment using hot and warm water during three ESA parabolic campaigns. A reflight with a further developed experimental set-up was performed during ESA PFC 39 in March 2005. The goal was to minimize the transport induced by the starting of the experiment. Two different methods to start the experiments were used: the shear cell method and the flowing junction cell method. The cells with a 4mm and 10mm thin capillary were fixed on an oscillating platform in three different positions: with an angle of 0°, 45° and 90° between the capillary axis and the acceleration vector.