Hydrodynamic Interactions of Bubbles in a Finite Container under the Influence of Periodic G-Jitter

抄録

The response of bubble ensembles to periodic accelerations was evaluated using BDH (Bubble Dynamics Handling) system designed for TR-IA #2 rocket launched in August 1992. Periodic accelerations with a low-level stationary acceleration were generated by the newly developed piezoelectric actuator. The time dependent function of g-jitter was formulated as: g(t)=0.60 X 10―4g+(2.l X 10―3 g) X cos(Z 1r X 1.4 7Hz X t). The generated g-jitter is a model of residual gravity in space station. Bubbles of 2-5mm in diameter were injected into silicone oil using a motor-driven syringe. The recorded behavior of bubbles showed sensitivity to periodic accelerations. Various kind of hydrodynamic interactions were confirmed. 1) Response to background residual gravity 2) Response to periodic accelerations generated by piezoelectric actuator 3) Increase of hydrodynamic drag due to the oscillatory motion of bubbles 4) Hydrodynamic interactions between bubble and wall 5) Hydrodynamic interactions between bubbles The accelerations of the hydrodynamic forces were evaluated at an order of 10―5g. Thus the phenomena cannot be observed under normal gravity. The results indicate the valuable use of the microgravity environment for the study of bubble dynamics under controlled accelerations.