Fluid behavior in three-dimensional vane-type surface tension tank under reduced gravity condition

The behaviors of ullage in a three-dimensional vane-type surface tension tank were investigated under reduced-gravity conditions. It was observed that the ullage was driven due to surface tension toward the gas inlet/outlet and remained on it. However, it was found that ullage separated under certain conditions depending on the shape and the number of vanes. The critical condition was derived by means of an analytical method and was verified by experiment. From the observation of liquid behaviors during the filling process, it was verified that there existed a critical filling rate at which the outlet flow of liquid through the gas inlet/outlet could be prevented. The critical filling rate increased with the number of vanes or when a baffle was set among the vanes.