Turbulent flow of liquid-liquid dispersions : drop size, friction losses, and velocity distributions
were studied under conditions of turbulent flow in a cirular
conduit. Experiments were conducted to obtain drop size, friction
factors and velocity profiles for three organic phases dispersed in
The test sections consisted of straight copper tubes 1-inch OD
and 0.830-inch ID. The velocity profiles and drop size measurements
were made at a point 8-1/2 feet downstream from the entrance
to these tubes. The dispersions were formed and maintained by the
mixing action of a high speed centrifugal pump. The organic phases
were a light petroleum solvent, a light oil and a heavy oil with viscosities
of 1, 15, and 200 centipoise, respectively. Flow rates were
in the range 1-4 lb/sec and concentrations from 5 to 50 volume
percent were studied.
A photographic method of drop size determination was developed.
Excellent results are obtained for drop diameters in the range
5-800 microns. Dispersions with concentrations from 1 to 50 volume
percent were photographed. The drop size and the shape of the drop
size distributions depended strongly on dispersed phase viscosity.
The range of drop diameters was found to increase with dispersed
Velocity profile data were obtained in the turbulent core for
three flow rates and four concentrations for the light oil dispersions
and two flow rates and three concentrations for the heavy oil dispersions.
The light oil dispersions were found to behave as single phase
Newtonian fluids. The solvent dispersions have previously been
shown to behave as single phase Newtonian liquids. The heavy oil
dispersions did not behave as Newtonian fluids. These results were
combined with the drop size data and a previously proposed criteria
for treating dispersions as single phase fluids to give the relation
[see PDF for formula] where d?? is the Sauter mean diameter of the dispersed drops.
Dispersions which do not meet this criterion are presumed to have a
"slip" velocity, i.e., the larger drops move relative to the fluid
element in which they are contained. Thus they do not behave as a single phase fluid.
The velocity profiles for the light oil dispersions were used to
calculate an effective dispersion viscosity [mu subscript e]. The viscosity increased
with dispersed phase concentration. Effective viscosities
for the solvent dispersion had been determined by previous workers.
A comparison of the viscosities and drop size data for these two
systems shows that at equal concentrations the effective viscosity of
a dispersion is a function of the drop size distribution, decreasing
with increasing size range. Effective viscosities for the heavy oil
dispersions were determined from the friction factor data and
appeared to be independent of concentration in the range 5 to 17
volume percent. This may be explained by a "slip" velocity and an
analysis of the drop size distributions.
A study was made of one water-in-solvent dispersion and it
was found that water droplets adhered to the pipe wall. The average
size of these droplets could be determined from the observed friction
factor data. The droplets adhering to the wall were observed to
undergo coalescence with the droplets in the flowing dispersion.
Several other observations made through the optical portion of the
photographic arrangement tend to support the coalescence theory
recently proposed by Howarth.
Advisor:Knudsen, James G.
School:Oregon State University
School Location:USA - Oregon
Source Type:Master's Thesis
Keywords:fluid dynamics turbulence
Date of Publication:04/23/1964