The Flow of the Mixture of Air and Water : III. The Friction Losses in Horizontal, Inclined and Vertical Tubes

1) Let ξ be the ratio of the actual friction loss of the two-phase flow to the friction loss obtained when the water alone flows through the tube, and also, let fw be the fraction of the water volume to the total tube volume. Then the following simple relation holds : ξ=fw-x, where Z is a function of the inclination alone and is from 1.4 to 1.9. 2) Let ψ be the ratio of the frictional coefficient of two-phase flow, as defined under consideration of the relative velocity, to the frictional coefficient of the single phase water flow. The ψ is a function of fw alone and falls in a range between 1 and 2. 3) The ratios ξ and ψ for the mixture of the saturated steam and water were obtained from the diagram by Martinelli and Nelson.