Prediction of interfacial shear stress of vertical upward adiabatic annular flow in pipes

Interfacial shear stress in annular two-phase flow is essential both for detailed modeling of two-fluid model and calculation of pressure gradient. Most of existing correlations on interfacial friction factor are based on Wallis's (1969) correlation, which considers the interfacial friction factor as a function of film thickness. As film thickness is a parameter not easy to obtain, it needs either high accuracy instrument to measure from experiment or to be calculated from available correlations. The calculated film thickness from available correlations introduces additional uncertainties to interfacial friction factor. Because of this, a new correlation of interfacial friction factor based on a group of non-dimensional numbers which are easy to obtain has been proposed. From data comparison, the new correlation has a mean absolute percentage error of 15% for all data listed in four databases.