A Dual Optical Probe For Hydrodynamic Parameters Measurements In Pulsed Sieve-Plate Column

Two-phase flow is defined as the simultaneous flow of liquid and gas（or vapour）or two immiscible liquid mixtures,and it occurs frequently in power-generation systems,nuclear reactors,bubble columns,heat transfer equipment and sub-sea oil-recovery bore wells.One of the primary characteristics of two-phase flow is the existence of fluid-fluid interfaces and,in experimental investigations of multi-phase flow,local phase-detection probes are of primary importance.Any experimental technique used in liquid-liquid two-phase flow should ideally be able to provide detailed information about the dispersed phase and/or the continuous phase,such as drop size,drop velocity and phase velocities at discrete points.This paper describes the development and application of a new dual optical probe system for drop velocity,drop size,local volume fraction measurements and discrimination of operations in liquid-liquid two-phase flows with particular reference to a kerosene-water flow.Moreover,the influences of operational parameters on the dispersed drop size,dispersed drop velocity and its distribution were investigated.Measurements were carried out in a large-scale vertical two-phase facility,which wasФ38mm pulsed sieve-plate column in this experiment,at the pipe centre-line to demonstrate the advantages of using optical fibers with normal cut ends in a kerosene-water two-phase flow.The experimental results show that dispersed drop velocity varied in a narrow interval and its distribution had a obvious probability.Five operations of pulsed sieve-plate column could be discriminated throughout signals detected by dual optical probe.The fitting formula of dispersed drop size wasd₃₂=153.68×V_c^-0.11V_d^-0.05（Af）^-0.93.The paper gives details of the optical interaction between the probe tip and the kerosene drop front and rear as well as the lay-out of the optical probe system for two-phase flow.What’s more,a dual optical probe has a fine applicability for measurements in gas-liquid two-phase flows and gas-kerosene-water three-phase flows.Experimental research proved the feasibility of the application of the dual optical probe technology to the liquid-liquid two-phase flow,found a method of accurately measuring distance between two probes,simplified process of making probe and reduced the volume of whole probe.