Abstract
Air-water flow was investigated in 65.8 and 122 mm columns packed with glass spheres of 5 different sizes (2.59-16.5 mm) up to air and water flow rates of G=2×104 and L=106 kg/m2 hr, respectively. Flow pattern is classified into 4 regimes and a diagram of flow-pattern boundary is prepared, including a new region of "dispersed bubble flow" observed for G<5×103 and L>105 kg/m2hr. Gas continuous flow always appears for L<104 kg/m2hr. For L = 104-105 kg/m2hr, pulse flow occurs only at intermediate air rate. Transitional region between gas continuous and pulse flow is very narrow.
Pressure oscillation detected at the wall is monotonous in gas continuous and dispersed bubble flow while five distinct modes of pressure pulsation are recognized in pulse flow region. The pressure rises sharply the moment the pulse front (leading edge of liquid-rich part of a pulse unit) passes the measuring point. This simultaneity was used to measure the pulse frequency and pulse velocity. Pulse velocity is much higher than the actual liquid velocity but lower than the actual gas velocity. Longitudinal acceleration of pulse velocity is also noted.
