Liquid film flow rate from measurements of disturbance wave characteristics for applications in thin film flow

Abstract

This paper discusses the development of a liquid-film thickness measurement technique using laser refractometry and the extension of this technique to enable the measurements of wave height, shape, frequency and velocity. The measurement technique is implemented in a falling water film facility for ease of method validation. The falling-film facility provides optical access to the film which allows the laser refractometry measurements to be compared to high-speed imaging of the waves directly. The total mass flow rate carried by the film (waves and base film) can be computed based on the laser refractometry measurement and compared to the actual liquid flow rate in the falling film facility in order to validate the technique without the complication of droplet entrainment that is typical in annular flow.