Interfacial area correlation for annular flow in vertical pipes

Interfacial area concentration is one of the most critical parameters in two-phase flow and reflects the interfacial area of mass, momentum and energy transfer. The prediction of interfacial area concentration is also essential to close the interfacial transfer terms in the two-fluid model. The calculation of interfacial area concentration has been well developed from bubbly flow to churn flow, including interfacial area correlations and two-group interfacial area transport equation. While seldom researchers focus on that for annular flow or annular mist flow. This paper proposed the one-dimensional interfacial area correlation for annular flow in vertical pipes based on the averaged liquid film thickness model for annular flow. The effects of the droplets in pipes were also considered in the model. The new model has been evaluated against the existing experimental data. The results indicate that the new model can provide the excellent prediction of the interfacial area concentration for annular flow in vertical pipes. (author)