Swirling Annular Flow in a Steam Separator

Effects of pick-off ring configuration on the separation performance of a downscaled model of a steam separator for a boiling water nuclear reactor are examined using various types of pick-off rings. The experiments are conducted using air and water. Pressure drops in a barrel and a diffuser, and diameters and velocities of droplets at the exit of the barrel are measured using differential pressure transducers and particle doppler anemometry, respectively. As a result, the following conclusions are obtained: (1) the separation performance does not depend on the shape of pick-off ring, but strongly depends on the width of the gap between the pick-off ring and the barrel wall, (2) the pressure drop in the barrel is well evaluated using the interfacial friction factor for unstable film flows, and (3) the radial distribution of droplet velocity at the exit of the separator is of use for the evaluation of carry-under.