Stability of Free Surface Flows in Capillary Channels with Rectangular Cross-Sections (English shop)

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This work deals with forced flow through partially open capillary channels under microgravity. The channels investigated consist of two parallel glass plates bounded by one or two liquid surfaces along the open sides. The shape of the channel resembles the capillary channels also used in propellant management devices of surface tension tanks of satellites. The flow in the channel becomes unstable when the free surface collapses and gas ingestion into the liquid flow occurs – a process also referred to as the “choking” phenomenon. Capillary techniques involving free surfaces are an important component for space-related and terrestrial applications. Since they contain no moving parts, they are a highly reliable method of liquid control. In this work, forced, isothermal and incompressible capillary flow is investigated theoretically, experimentally and numerically. The previously published stability theory has been subjected to an in-depth review. A long-term experiment (CCF – Capillary Channel Flow) was carried out on the International Space Station ISS in order to validate the theory and to determine its range of validity within a multidimensional parameter space.