Optical measurements of the velocity, height and frequency of disturbance waves in saturated two-phase annular flow

摘要: In two-phase annular flows, disturbance waves, ie, large waves several times thicker than the mean thickness of the liquid film, strongly affect the heat transfer coefficient and pressure drop. In this study, an optical technique is used to simultaneously measure the instantaneous velocity and height, as well as the frequency of disturbance waves in an adiabatic two-phase annular flow of saturated R245fa. Instantaneous liquid film thickness is measured using the optical method initially proposed by Shedd and Newell (1998, https://doi. org/10.1063/1.1149232). In this method, the liquid film thickness is calculated from ring patterns made by light reflected at the interface of the liquid film. A new strategy for the post-processing of the ring patterns has been developed that allows the measurement of the instantaneous disturbance wave velocities. Detailed characterization of wave velocity, height, and frequency will be …