Thesis (MTech (Chemical Engineering))--Cape Technikon, 2004 / When designing the open channels to transport the homogenous non-Newtonian slurries, the
effect of channel shape is one of the parameters that should be checked and very little research
has been conducted to address this matter. Open channels are commonly applied in the mining
industry where mine tailings have to be transported to the disposal dams at high concentrations
to save water consumption. This thesis addresses the effect of the cross-sectional shape of the
channel with emphasis on laminar and transitional flow of non-Newtonian fluids.
The literature review on the flow of Newtonian and non-Newtonian fluids has been presented.
The most relevant one to this topic is the work done by Straub et al (1958) for Newtonian
fluids and the analytical work presented by Kozicki and Tiu (1967) for non-Newtonian fluids.
Authors like Coussot (1994) and Haldenwang (2003) referred to their work but did not
comprehensively verified it experimentally.
Three flume shapes were designed to investigate this problem namely, rectangular, semi
circular, and trapezoidal flume shape. The test rig consisted of a 10 m long by 300mm wide
tilting flume that can be partitioned into two sections to form a 150 mm wide channel. All
three flume shapes were tested in both the 150 mm and 300 mm wide flumes. This flume is
linked to the in-line tube viscometer with three tube diameters namely, 13 mm; 28 mm; and 80
mm. The experimental investigation covered a wide range of flow rates (0.1-45l/s), and flume
slopes (1-5 degrees). The fluids tested were kaolin suspension (5.4 - 9% v/v), CMC solution (1
- 4% m/m), and bentonite suspension (4.6 and 6.2% mlm).
The models found in the literature were evaluated with the large database compiled from the
test results to predict the laminar and transitional flow of these fluids with the aim of checking
the effect of the cross-sectional shape of these channels selected in these flow regimes.
For all the flume shapes and non-Newtonian fluids selected in this thesis it was found that in
predicting the laminar flow, the effect of shape is adequately accounted for by the use of
hydraulic radius. In predicting the transitional flow, it was found that the effect of shape does
not have to be included.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:cput/oai:localhost:20.500.11838/874 |
| Date | January 2004 |
| Creators | Vanyaza, Sydwell Luvo |
| Publisher | Cape Technikon |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Rights | http://creativecommons.org/licenses/by-nc-sa/3.0/za/ |
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