Thesis (MScEng)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: Mixed flow fans find application in an operating region between that of axial flow and
centrifugal fans. The candidate investigated the working of these mixed flow fans and
formulated a design algorithm. The algorithm was based on work done by previous authors,
most of which have tried to modify existing axial flow fan design methods to suit the mixed
flow case. A fan was designed, built and tested. Tests showed that the fan did not perform as
designed, producing a lower pressure rise at a lower flow rate. A five hole probe was used to
measure the exit flow vector and the results showed that most of the work was done by the
lower half of the blade. Based on this discrepancy between the designed and actual fan
performance, a number of changes to the design procedure were recommended. Amongst
other things: the use of numerical blade modelling procedures instead of modified cascade
correlations and the disregard of the Coriolis work in the design of the blade shape. / AFRIKAANSE OPSOMMING: Gemengde vloei waaiers bevredig die behoefte aan 'n waaier in 'n spesifieke werksgebied
waar aksiaal en sentrifugale waaiers minder effektief is. Die projek ondersoek die werking
van gemengde vloei waaiers en formuleer 'n ontwerp-algoritme. Die algoritme is gebaseer op
bestaande navorsing, waarvan die meeste 'n poging is om aksiaalvloeiwaaiermetodes aan te
pas vir die gemengde vloei geval. 'n Waaier is ontwerp, gebou en getoets. Toetsresultate toon
dat die waaier 'n laer drukstyging by 'n laer volume vloei gee as wat die ontwerp voorspel. 'n
Vyfgat-anemometer is gebruik om die uitlaatvloei-vektor te meet en die resulate het bewys
dat die gedeelte van die rotorlem naaste aan die naaf meeste van die werk doen. Hierdie
afwyking van die ontwerptoestand is ondersoek en 'n aantal veranderings aan die ontwerp
algoritme is voorgestel, naamlik: die gebruik van numeriese lemprofiel simulasie, instede van
die glip- en deviasie- modelle, en die ontwerp van die lemprofiel deur die Coriolis werk te
Ignoreer.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/52665 |
| Date | 03 1900 |
| Creators | Du Toit, Jacques H. (Jacques Hendrik) |
| Contributors | Von Backstrom, T. W., Basson, A. H., Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 1 v. (various foliations) : ill. |
| Rights | Stellenbosch University |
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