Study on Closure Equations of Droplet Drag and Interfacial Shear Stress for Three-Field Model

Abstract

Interfacial shear stress and liquid film thickness is important for the estimation of deposition and entrainment rates which are used in three-field models. An analytical model was developed to estimate interfacial and wall friction factors and drag coefficient which are used to estimate the interfacial shear stress and liquid film thickness. As the results, for the annular-mist flow in very high gas superficial velocity condition, the analytical results of the interfacial friction factor were reasonably agree with the Wallis' correlation for the interfacial friction factor which was developed purely based on the experimental data. And the calculated results of wall friction factor were agreed with the equation for the laminar flow. This reason is supposed that the liquid film thickness is very thin less than transition region in the annular-mist flow under high gas superficial velocity region. Furthermore, it was indicated that Kataoka's correlation for droplet diameter is applicable for the prediction of drag force in the annular-mist flow.