Large Bubble Motion in a Fluid Cell under Microgravity: ISCAP Experiments on the Effects of g-jitter and Forced Vibration

Abstract

The motion and deformation of a large gas bubble in a liquid-filled cell were experimental­ ly investigated under microgravity and forced vibration conditions. The experiment was con­ ducted aboard the Space Shuttle during the STS-85 mission, using a vibration isolation platform (MIM) to either isolate the cell from g-jitter or to impose controlled vibrations of specified frequency and amplitude. The experiments were conducted using two shallow, cylindrical fluid cells (97.3 mm I.D. x 16.8 mm thickness), each containing a mixture of air/miner­al oil (cell #1) and air /water-surfactant solution (cell #2). In microgravity, a large air bubble formed in the middle of the cell, and the motion of the bubble and gas-liquid interface was recorded by a video camera under different test conditions. In the isolation mode, high frequency g-jitter above MIM's cutoff frequency of 2 Hz was significantly attenuated, but the low frequency vibrations were transmitted and found to influence the bubble interface. In the forced vibration tests, the large bubble responded to periodic vibrations of low frequency and large amplitude, rather than high frequency and high acceleration level. Bubble movement and non-linear shape oscillation data were obtained and analyzed.