Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering. / Thesis (MEng)--Stellenbosch University, 1990. / ENGLISH ABSTRACT: The causes of disturbances in the flow patterns at the
inlets of axial flow fans that are used in mechanical draft
cooling towers and the effects of these disturbances on the
fans, were investigated.
A scale model of a part of a mechanical draft cooling tower
used at a power station was built for the purpose of this
study. In the cooling tower the axial flow fans are
arranged in a matrix configuration. It was noted from the
scale model that the boundary fan was subjected to the
worst inlet disturbances and this had an adverse effect on
the flow it produced. Geometric alterations like the use
of guide vanes and rounded inlets improved the flow through
the boundary fan considerably. It was found that the
performance of the fans is a function of the number of fans
used and the elevation of the fans.
Several tests to determine the performance of the cooling
tower confirmed the results obtained from the experiments
on the scale model. It was also found that the speed and
direction of the prevailing wind have a significant effect
on the cooling tower.
Experiments to investigate the effects of cross-flow at the
inlet of a fan indicated an increased flow through the fan
at low cross-flow velocities and that the flow decreased at
high cross-flow velocities. / AFRIKAANSE OPSOMMING: Die invloed en oorsake van versteurde inlaatvloeipatrone op
aksiaalwaaiers wat in meganiese-trek koeltorings gebruik
word is ondersoek.
'n Skaaimodel van 'n deel van 'n meganiese-trek koeltoring
wat by 'n kragstasie gebruik word is gebou vir die doel van
die studie. Die aksiaalwaaiers wat in die koeltoring
gebruik word is in 'n matrikskonfigurasie gerangskik.
Vanaf die skaalmodel is waargeneem dat die randwaaier die
ergste versteuring by die inlaat ervaar, en gevolglik
minder vloei as die res van die waaiers in die opstelling
lewer. Die vloei deur die randwaaier is verbeter deur
verskillende geometriese wysigings soos leilemme en
inlaatafrondings aan te bring. Daar is gevind dat die
werking van die waaiers in die opstelling 'n funksie van
die hoeveelheid waaiers asook die grondvryhoogte is.
Om die werking van die koeltoring te bepaal is verskillende
toetse daarop uitgevoer. Die resultate het die geldigheid
van die skaalmodel bevestig. Daar is ook gevind dat die
heersende windsterkte en rigting 'n definitiewe invloed op
die koeltoring uitoefen.
Die invloed van 'n dwarsvloei by die inlaat van 'n enkele
waaier is ook eksperimenteel ondersoek. Die resultate toon
dat daar 'n vermeerdering in vloei deur die waaier by lae
dwarsvloeisnelhede plaasvind. Hoë dwarsvloeisnelhede
veroorsaak egter 'n vermindering in vloei.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/21767 |
| Date | 12 1900 |
| Creators | Visser, J. G. J. |
| Contributors | Kroger, D. G., University of Stellenbosch. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | Afrikaans |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 350 p. : ill. |
| Rights | Stellenbosch University |
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