Abstract
Frictional pressure drops of horizontal adiabatic air-water two-phase flow in Pyrex grass tubes with inside diameters of around 1,2,4 mm, respectively, were measured. The experimental results are compared with the author's previous experiment on heated air-water vertical flow with stainless steel tube of 2 mm I.D., and good agreement is obtained between the present and previous experimental results. Two-phase multiplier Ф_l^2 is correlated very well by Chisholm-Laird's equation at relatively large liquid and gas superficial velocities, whereas Mishima-Hibiki's modified correlation for small diameter tube is valid for the case where the liquid superficial velocity is low. This depends on Reynolds number of liquid phase. Transition from laminar to turbulent flow is considered to occur at liquid phase Reynolds number of around 1000.
