Investigation of vertical slug flow with advanced two-phase flow instrumentation

Extensive experiments of vertical slug flow were carried out with an electr omagnetic flowmeter and an impedance void-meter in an air-water two-phase e xperimental loop. The basic principles of these instruments in vertical slu g flow measurements are discussed. Time series of the liquid velocity and t he impedance were separated into two parts corresponding to the Taylor bubb le and the liquid slug. Characteristics of slug flow, such as the void frac tions, probabilities and lengths of the Taylor bubble and liquid slug, slug unit velocity, area-averaged liquid velocity, and liquid film velocity of the Taylor bubble tail, etc., were obtained. For the first time, the area-a veraged liquid velocity of slug flow was revealed by the electromagnetic fl owmeter. It is realized that the void fraction of the liquid slug is determ ined by the turbulent intensity due to the relative liquid motion between t he Taylor bubble tail region and its wake region. A correlation of the void fraction of the liquid slug is developed based on experimental results obt ained from a test section with 50.8 mm i.d. The results of this study sugge st a promising improvement in understanding of vertical slug flow. Publishe d by Elsevier Science B.V.