Experimental studies have been performed for horizontal two-phase air-water flows at nor-mal and reduced gravity conditions in a square cross-section channel. The experiments at reducedgravity are conducted on board the Russian IL-76 reduced gravity airplane. Four flow patterns, namelybubble, slug, slug-annular transition and annular flows, are observed depending on the liquid and gassuperficial velocities at both conditions. Semi-theoretical Weber number model is developed to includethe shape influence on the slug-annular transition. It is shown that its prediction is in reasonable agree-ment with the experimental slug-annular transition under both conditions. For the case of two-phasegas-liquid flow with large value of the Froude number, the drift-flux model can predict well the observedboundary between bubble and slug flows.
Processes of the onset oscillation in the thermocapillary convection under the Earth's gravity are investigated by the numerical simulation and exper- iments in a floating half zone of large Prandtl number with different volume ratio. Both computational and experimental results show that the steady and axisymmetric convection turns to the oscillatory convection of m=l for the slender liquid bridge, and to the oscillatory convection before a steady and 3D asymmetric state for the case of a fat liquid bridge.It implies that,there are two critical Marangoni numbers related,respectively,to these two bifurcation transitions for the fat liquid bridge.The computational results agree with the results of ground-based experiments.
The magnetic damping effect of the non-uniform magnetic field on the floating-zone crystal growth process in microgravity is studied by numerical simulation. The results show that the non-uni-form magnetic field with designed configuration can effectively reduce the flow near the free surface and then in the melt zone. At the same time, the designed magnetic field can improve the impurity concen-tration non-uniformity along the solidification interface. The primary principles of the magnetic field con-figuration design are also discussed.
An experimental set up was designed to separately test how sedimentation and convection driven flows affect the perikinetic coagulation process in a ground based experiment.The experiment showed that the sedimentation slightly accelerates the coagulation process and weak free convection driven flows do not noticeably contribute to coagulation for 2 μm particles’ dispersion.
