The research described in this thesis has been focused on the detailed investigation of horizontal
co-current liquid-liquid two-phase flows. The experiments were carried out in channels of
square and circular cross section and involved the use of two immiscible liquids of matched
refractive index; namely an oil (Exxol™D80) and a 81.7 wt% glycerol-water solution. The
experiments were carried out in a refurbished liquid-liquid flow facility (TOWER) and the focus
was on examining the flows using high-speed laser-based visualisation methods which allowed
both qualitative evaluation of the nature of the flows (i.e. the flow patterns) and quantitative
measurements of parameters such as drop size and velocity distribution. The laser-based
techniques used included Planar Laser Induced Fluorescence (PLIF), Particle Tracking
Velocimetry (PTV) and Particle Image Velocimetry (PIV). Using these techniques, it was
possible to obtain high spatial and temporal resolution measurements of velocity and phase
distribution of liquid-liquid flows which enabled the detailed diagnostic inspection to an extent
that has not been previously possible. 144 experiments were carried out in three experimental
campaigns. In the first campaign, a square cross section channel was used in order to avoid
image distortion by the channel walls. In the second and third campaigns, a circular tube was
employed and a graticule correction method was used to correct the distortion to the PLIF and
PTV/PIV images which occurs when the circular cross-section visualisation cell is used. In the
two circular tube experiments, two methods of injection of the phases were used: (1) the heavier
(glycerol solution) phase was injected in its natural location at the bottom of the channel, and
(2) in the second case the heavier phase was injected at the top of the channel.
The PLIF images gave a clear indication of the distribution of the phases at the channel centre
line and have been used qualitatively in obtaining information about the flow patterns occurring. The PLIF images have also been used quantitatively in generating data on phase distribution, insitu
phase fraction, interface level and drop size distribution. Much of the data on in-situ phase
fraction and interface level fits well with a simple laminar-laminar stratified flow model. The
PTV/PIV method provided extensive data on velocity profiles; in the lower (aqueous glycerol
solution) phase, the profile usually showed the curved shape characteristic of laminar flow and
in the upper (Exxol™D80) phase, the velocity profile often showed the flattened form
characteristic of turbulent flow
