Interfacial area increase in rippled film flow on wetted wall columns

Abstract

The problem of the evaluation of the area of random surface is discussed, and the result of the analysis is applied to the measurement of the interfacial surface area of rippled liquid films. The experimental method is based on extraction of information from photographic plates of dyed liquid films flowing down glass wetted wall collumns, and recording the data on to an 8-channel computer tape. The tape was processed in an Elliot 503 computer which gave the increase in interfacial area as a function of the height of the wetted plate, and the liquid flow rate for several liquids. The influence of countercurrent and cocurrent air blow was also examined. Some 150 measurements of the increase in interfacial area were made. The results show that the increase in interfacial area due to rippling is small under ordinary conditions of flow in wetted wall columns and does not change appreciably with air blow for air velocities below a certain critical value.