Droplet size measurements in horizontal annular gas-liquid flow

Measurements of drop size distributions in air-water annular flow have been made in a horizontal 0.0953 m pipe, at atmospheric pressure. A laser diffr action technique has been employed; using a Malvern Spraytec R5008 instrume nt. Stratification of the droplets has been observed by obtaining measureme nts at the pipe centre line, and 0.019 m above and below it. The stratifica tion, which is caused by the effects of gravitational settling and the asym metry of the liquid film, decreases with increasing gas velocity. Measured Sauter mean diameters at the pipe centre are similar to what has been obser ved in vertical pipes. However, they show a stronger effect of liquid flow rate than predicted by the correlation of Azzopardi, that was developed fro m measurements made with an earlier diffraction technique that did not acco unt for multiple scattering. A log-normal or an upper limit log-normal dist ribution underpredicts the measured contributions of small diameter drops. (C) 2001 Elsevier Science Ltd. All rights reserved.