Abstract
The flow characteristics of slender-column flow in wedge-shaped channel under microgravity condition are investigated in this work. The one-dimensional theoretical model is applied to predict the critical flow rate and surface contour of stable flow. However, the one-dimensional model overestimates the critical flow rate for not considering the extra pressure loss. Then, we develop a three-dimensional simulation method with OpenFOAM, a computational fluid dynamics tool, to simulate various phenomena in wedge channels with different lengths. The numerical results are verified with the capillary channel flow experimental data on the International Space Station. We find that the three-dimensional simulation perfectly predicts the critical flow rates and surface contours under various flow conditions. Meanwhile, the general behaviors in subcritical, critical, and supercritical flow are studied in three-dimensional simulation considering variations of flow rate and open channel length. The numerical techniques for three-dimensional simulation is validated for a wide range of configurations and is hopeful to provide valuable guidance for capillary channel flow experiment and efficient liquid management in space.
Highlights
Open capillary channel is a structure that contains a liquid with one or more gas–liquid interfaces, which plays an important role in a number of applications in liquid management in space science, such as heat pipes and propellant management devices (PMD) in on-orbit refueling tanks of satellites.[1,2]
It is worth mentioning that we found the change rate of free surface is related to the acceleration time period Dt1
The capillary channel flow (CCF) experiments on ISS developed a broad study on the stability of open channel flow under microgravity conditions with a large range of parameters
Summary
Open capillary channel is a structure that contains a liquid with one or more gas–liquid interfaces, which plays an important role in a number of applications in liquid management in space science, such as heat pipes and propellant management devices (PMD) in on-orbit refueling tanks of satellites.[1,2] Under the condition of microgravity, the gravity is negligible and the flow in the channel is dominated by convection, viscous stress, and surface tension. With the increase in flow rate, the pressure difference across the gas–liquid interface gradually increases, and the free surface has to bend inward to balance it. Once the growth rate of pressure difference exceeds the surface curvature change rate, the surface collapses and gas ingests into the channel. This phenomenon is called choking, and we call it as supercritical phenomenon, which is undesired for many applications. The maximum flow rate is reached before the free surface becomes unstable.
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