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The effect of pipe roughness on non-Newtonian turbulent flow
Author(s)
Van Sittert, Fritz Peter
Date Issued
1999
Type
Thesis
Publisher
Cape Technikon
Abstract
Pipe roughness is known to greatly increase the turbulent flow friction factor for
Newtonian fluids. The well-known Moody diagram shows that an order of magnitude
increase in the friction is possible due to the effect of pipe roughness. However, since the
classical work of Nikuradse (1926 -1933), very little has been done in this area. In
particular, the effects that pipe roughness might have on non-Newtonian turbulent flow
head loss, has been all but totally ignored.
This thesis is directed at helping to alleviate this problem. An experimental investigation
has been implemented in order to quantify the effect that pipe roughness has on non-Newtonian
turbulent flow head loss predictions.
The Balanced Beam Tube Viscometer (BBTV), developed at the University of Cape Town,
has been rebuilt and refined at the Cape Technikon and is being used for research in this
field.
The BBTV has been fitted with pipes of varying roughness. The roughness of smooth P\'C
pipes was artificially altered using methods similar to those of Nikuradse. This has enabled
the accumulation of flow data in laminar and turbulent flow in pipes that are both
hydraulically smooth and rough Newtonian and non-Newtonian fluids have been used for
the tests.
The data have been subjected to analysis using various theories and scaling laws. The
strengths and problems associated with each approach are discussed and It is concluded that
roughness does have a significant effect on Newtonian as well as non-Newtonlan flow.
Newtonian fluids. The well-known Moody diagram shows that an order of magnitude
increase in the friction is possible due to the effect of pipe roughness. However, since the
classical work of Nikuradse (1926 -1933), very little has been done in this area. In
particular, the effects that pipe roughness might have on non-Newtonian turbulent flow
head loss, has been all but totally ignored.
This thesis is directed at helping to alleviate this problem. An experimental investigation
has been implemented in order to quantify the effect that pipe roughness has on non-Newtonian
turbulent flow head loss predictions.
The Balanced Beam Tube Viscometer (BBTV), developed at the University of Cape Town,
has been rebuilt and refined at the Cape Technikon and is being used for research in this
field.
The BBTV has been fitted with pipes of varying roughness. The roughness of smooth P\'C
pipes was artificially altered using methods similar to those of Nikuradse. This has enabled
the accumulation of flow data in laminar and turbulent flow in pipes that are both
hydraulically smooth and rough Newtonian and non-Newtonian fluids have been used for
the tests.
The data have been subjected to analysis using various theories and scaling laws. The
strengths and problems associated with each approach are discussed and It is concluded that
roughness does have a significant effect on Newtonian as well as non-Newtonlan flow.
Additional information
Thesis (MTech (Civil Engineering))--Cape Technikon, Cape Town, 1999
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