Secondary instability of waves in annular two-phase flow with and without entrainment

Abstract

Spatio-temporal evolution of disturbance waves and ripple waves in annular gas-liquid flow was studied using high-speed modification of laser-induced fluorescence technique. Both flow regimes with and without entrainment were studied. It was shown that all the ripples in regimes with entrainment arise due to instability of back slopes of the disturbance waves, and their further evolution is predefined by the point of appearance. In regimes without entrainment two types of waves were detected, where waves of one type arise due to instability of back slopes of waves of the other type. Thus, similarity of wavy structure of flow regimes with and without entrainment was established. © 2010 IOP Publishing Ltd.