Multiphase/Interfacial and Turbulent Flows Division

Annular Flows


Horizontal and Vertical Flow Characterisation

 

This work involves experimental characterisation of liquid-liquid flows in a horizontal circular tube. The flows are investigated at the test section with the application of laser-based optical diagnostic methods, which included high-speed simultaneous Planar Laser Induced Fluorescence (PLIF), Particle Image Velocimetry (PIV) and Particle Tracking Velocimetry (PTV). These techniques allow the reliable evaluation of the nature of the investigated horizontal liquid-liquid flows (i.e., the flow patterns from phase distribution information), together with the detailed spatiotemporally resolved measurement of key flow characteristics such as phase and velocity distributions, and also of important parameters such as droplet size.

The resulting PLIF images provide a clear indication of the distribution of the phases within a plane that passed through the channel centreline, and are used to obtain qualitative information about the arising flow patterns. The images are also used quantitatively to generate data on phase distribution, in situ phase fraction, interface level and droplet size distribution.

Downwards Downward Annular Flowsco-current gas–liquid annular flows are also studied experimentally and characterised. Advanced optical laser-based measurements using Planar Laser-Induced Fluorescence (PLIF), are used for the visualisation of the annular flow over a range of liquid Reynolds numbers and gas Reynolds numbers.

Four distinct flow regimes, namely the ‘dual-wave’, ‘thick ripple’, ‘disturbance wave’ and ‘regular wave’ regimes, have been identified based on qualitative information and a consequent quantitative analysis that provided information on the film thickness, interface and wave statistics, and gas entrainment into the liquid film.

The mean film thickness data are generally in good agreement with previous studies. Evidence suggests that the turbulent gas phase affects strongly the shape of the interface, and that the mechanism for gas entrainment into the liquid film is strongly reliant on the existence of large-amplitude waves.

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 

Annular Flows

Drag Reduction


Investigation of Drag Reduction and Polymer Degradation in Rough Pipes

In the Drag Reduction Experiment and Diagnostic (DREAD) rig pipe flow experiments are conducted to further understand the mechanism of drag reduction and the parameters that affect it. The effect of parameters such as polymer concentration, polymer type, molecular weight and aggregation time, on the level of drag reduction and on the degradation of the polymer in turbulent flow are studied. A novel mechanism that is able to explain the inhomogeneity of the polymer concentration profile across the pipe section when drag reduction is occurring has been proposed.

Drag Reduction