Assessment of Entrainment Rate Correlations for Annular Flow Based on Disturbance Wave Crests

Annular flow is characterized by a high velocity gas core flow, with a thin liquid film around it, adjacent to the pipe wall. It is frequently observed in a wide range of industrial facilities, in particular during oil and gas exploitation, where high gas-oil ratios are found. Droplet entrainment and deposition have relevant impact on annular flow properties, such as pressure drop and film thickness, as vastly shown in literature. Several authors have described physical mechanisms for droplet entrainment and deposition; many of those are related to disturbance waves. The objective of the present study is to assess the performance of droplet entrainment correlations in which droplets are created by shear at the disturbance waves' crests. A model framework based on the 1-D Two-Fluid model is employed with a high-resolution mesh. The model allows capturing the automatic evolution of the gas-liquid interface and the formation of liquid film waves and their influence on droplet entrainment and deposition. The performance of the model is evaluated for vertical flow, showing good agreement with experimental data found in literature.