Optical Measurement of Base Film Thickness in Annular Two-Phase Flow

Measurements of the film thickness of annular two-phase air-water flow have been taken using an optical technique that extracts the base film thickness, excluding the input of waves. Both horizontal and vertical conditions have been examined. The technique used, originally developed by Shedd and Newell, uses the pattern of diffuse light reflected from the liquid surface. Two correlations for average base film thickness are provided; one is a purely empirical fit, while the other employs a critical friction factor. An empirical relation for maximum horizontal asymmetry in terms of a Froude number is also provided.