A technical review of research progress on thin liquid film thickness measurement

Abstract

The thickness of the thin liquid film and its effects have always been a research hotspot in nuclear power applications and operating nuclear power plants, because the flow phenomenon of the liquid film is extremely common in multiphase flow research. Based on papers published in recent years, novel research progress on thin film thickness is reviewed from the following two perspectives: the experimental measurement and the theoretical model of liquid film thickness. For the experimental measurement, methods mainly include the PLIF method, the capacitance method, and the ultrasonic method. The following contents in this part are mainly reviewed from the PLIF method, the capacitance method, the ultrasonic method, and other methods for the measurement of the liquid film thickness on the wall, the liquid film thickness on the tube wall, and other aspects of the liquid film thickness. For the model, the theoretical model of liquid film thickness on the wall is mainly reviewed from two aspects: vertical flow and horizontal flow. Other models are mainly reviewed from the following aspects. They are annular film thickness, liquid film thickness for gas-liquid annular flow, and film thickness in pipes.

A novel methodology to measure the film thickness profile based on current stimulation for two-phase flow

“…The first model consists of the bubble's nose, which presents a radius with a spherical shape, defined as equation (21).…”

“…On the other hand, the optical methods are based on the emission of lights into the different phases, which presents a gradient at the interface. Wang et al [21] presented a review about the measurement of liquid film thickness. Some methods are based on high-speed cameras, which the quantity can be processed from the image.…”

Measuring liquid film thickness during downflow condensation in a minichannel

“…Han et al [8] employed a laser confocal displacement meter for measuring the liquid film thickness during IOP Publishing doi:10.1088/1742-6596/2766/1/012131 2 annular flow of degassed water and air inside tubes with 0.3, 0.5 and 1.0 mm inner diameters. Numerous models for liquid film thickness have been proposed in the past decades and validated against wide experimental databases [9,10]. In general, the number of dimensionless groups that should be included in liquid film thickness models is not well established.…”