A Discussion on the Relation Between the Intermittent Flow Sub-Regimes and the Frictional Pressure Drop

The influence of sub-regimes of intermittent flow on the pressure drop has been investigated. Two-phase, air-water, flow experiments were conducted on 30 mm ID pipe. The superficial velocities of the working fluids were chosen to cover three sub-regimes: Plug flow, Less Aerated Slug flow (LAS flow) and Highly Aerated Slug flow (HAS flow). The analysis of the experimental data, including the data drawn from the literature showed that the pressure drop depends on the flow sub-regime. A new empirical correlation, based on the Lockhart-Martinelli approach, taking into account the nature of sub-regime was proposed. The present correlations, in comparison with the existing correlations, give the best results.