Study of Entrance Geometry Effect on Flooding and Analysis Using Local Void Fraction

Abstract

The entrance geometry effect on flooding was examined in vertical air-water countercurrent flow. Flooding occurred by a drastic amplification of local interfacial disturbance generally initiated at the upper or lower entry. In order to analyze the flooding phenomena, the local flow properties at these entries should be understood. The void fraction measured at the upper entry with a sharp-edged geometry was related to the liquid flow rate. The critical wavelength based on the theory of interfacial wave instability presented by Imura et al. was only correlated with the tube diameter for the upper entry with a sharp-edged geometry. The correlation and the void fraction relationship to the liquid flow rate at the upper entry produced good predictions of flow rates at the onset of flooding.