ONSET OF SLUGGING CRITERION BASED ON CHARACTERISTICS AND STABILITY ANALYSES OF TRANSIENT ONE-DIMENSIONAL 2-PHASE FLOW EQUATIONS OF 2-FLUID MODEL

A two-step approach has been used to obtain a new criterion for the on set of slug formation: (1) In the first step, a more general expressio n than the existing models for the onset of slug flow criterion has be en derived from the analysis of singular points and neutral stability conditions of the transient one-dimensional two-phase flow equations o f two-fluid model. (2) In the second step, introducing simplifications and incorporating a parameter into the general expression obtained in the first step to satisfy a number of physical conditions a priori sp ecified, a new simple criterion for the onset of slug flow has been de rived. Comparisons of the present model with existing models and exper imental data show that the present model agrees very closely with Tait el & Dukler's model and experimental data in horizontal pipes. In an i nclined pipe (theta = 50 degrees), however, the difference between the predictions of the present model and those of existing models is appr eciably large and the present model gives the best agreement with Ohnu ki et al.'s data.