Abstract
The purpose of this series of study is to clarify the effects of surface tension on vertical upward annular flows in a 5 mm I.D. pipe. Water and PLE (aqueous solution of a little surfactant, Polyoxyethylene Lauryl Ether, being about 40% lower surface tension than water) were used as the test liquid, while air as the test gas. Experimental data on mean liquid film thickness, liquid droplet fraction, interfacial shear stress and frictional pressure drop were obtained together with flow pictures. In these, frictional pressure drop is mainly discussed in the present paper. It is cleared that the frictional pressure drop is higher in the low surface tension case. The cause of this is considered to be due to rough interface between liquid film and gas core, high liquid droplet fraction, thin liquid film thickness and high interfacial shear stress, as reported in our previous paper. Thus, firstly, the main findings in our previous paper are briefly introduced. Secondary, pressure drop data have been presented and used to test correlations in literatures, and a new prediction method has been proposed by accounting for the surface tension effects.
