An experimental study of the void fraction distribution in adiabatic water-air two-phase flows in an inclined tube

A fibre optical probe is used to measure the radial distribution of void fr action and bubble frequency of adiabatic water-air two-phase flow in an inc lined tube. Three typical void fraction distributions can be established fo r vertical two-phase flow: sliding bubble flow, coring bubble flow, and an intermediate type. These typical distributions are influenced by the angle of inclination in different ways. In case of coring bubble flow, the void f raction maximum near the tube axis moves to the upper part of the cross-sec tion when the vertical tube changes to the horizontal position. In case of sliding bubble flow, one of the void fraction maxima near the tube wall is increased (upper part of cross-section) and the other one is decreased (low er part of cross-section) when the inclination changes from vertical to hor izontal. The flow pattern transition can also be seen in the change of equi valent bubble diameters. (C) Elsevier, Paris.