Upward Liquid Flow in a Small Tube into which Air Streams : 4th Report, Pipe Friction II

Abstract

A study of pressure gradient of an air-liquid two-phase flow which streams upward after confluence in a small tube is made. In this paper, the pressure gradients of flows in the region of high ratio of supplied air and liquid flow, that is, piston, froth, annular and long piston flows are reported. In these flow patterns, the tendency of an unestablished flow is strong, and especially the difference of pressure gradient between upper and down streams in forth flow is large. Depending on conditions of mixing air and liquid, there is a region in the part of froth flow in which a steady rate of air flow can not exist. The pressure gradient of piston flow is small, and we must be cautious about the definition of its pipe friction. The nondimensional empirical equations for the pressure gradient of each flow pattern are obtained, and one equation which covers the whole region, is also obtained for supplementary purpose, though it is an estimation somewhat short of preciseness.