Abstract
Counter-current flow limitation (CCFL) characteristics at the sharp-edged upper end (CCFL-U) of a vertical pipe with the diameter of D = 20 mm were measured, and effects of diameters on CCFL-U were evaluated by using CCFL-U data obtained from this study, measured by Doi et al. (2012) with D = 30, 45 and 60 mm, and reported by Richter (1981) with D = 19～140 mm. CCFL-U could be expressed by the Kutateladze parameters with the Laplace capillary length for the characteristic length in the range of D ≥ 25 mm. CCFL-U characteristics in small diameters of D ≤ 45 mm, however, strongly depended on the system characteristics such as the shape of the upper tank and the water level in the upper tank. CCFL-U characteristics in this study with D = 20 mm were clearly different with those for D ≥ 25 mm, and were different with those with D = 19 mm reported by Richter (1981). The reason of the differences is not clear.
