The effect of hub configuration on the performance of an air-cooled steam condenser fan

Meiring, Zander (2020-03)

Thesis (MEng)--Stellenbosch University, 2020.

Thesis

ENGLISH ABSTRACT: Axial flow fans used in air-cooled condensers are typically analysed with smooth rounded hubs due to their superior performance. However, such a hub increases the manufacturing and installation costs of air-cooled condensers. As such, it is desirable to use a simpler hub geometry to reduce the total installation cost. This thesis assesses the impact that a simpler hub configuration may have on the performance of an axial flow fan. This is done through a comparison of four hub configurations: a round hub, as quare hub, and two disk hubs. Computational fluid dynamics modelling utilizing the open-source software code, OpenFOAM, is used to simulate each hub configuration. BlockMesh is used to generate the computational mesh required. It is found that the impact on performance due to hub geometry is dependent on the volumetric flow rate through the fan. At above design point flow rates, the square hub configuration has the best performance, providing a 9.5 % increase in total-to-static pressure rise and a 5.1 % point improvement in totalto- static efficiency compared to the round hub. On the other hand, a centre disk hub provides a 8.4 % improvement in total-to-static pressure rise and a 5.7 % point improvement in total-to-static efficiency when compared to the round hub at 62.5 % of the design flow rate. At the design point flow rate the round and square hubs result in a very similar performance, and superior to the disk hub configurations.

AFRIKAANSE OPSOMMING: Aksialvloeiwaaiers wat gebruik word in lugverkoelde stoom-kondensors word tipies ontleed met ’n gladde geronde naaf weens beter werkverrigting van hierdie konfigurasie. So ’n naaf verhoog egter die koste van vervaardiging en installasie van die verkoelingswaaier. As sulks, is dit wenslik om ’n meer eenvoudige naaf konfigurasie te gebruik om die totale prys van installasie te verminder. Hierdie tesis evalueer die impak op werkverrigting van ’n verkoelingswaaier met ’n meer eenvoudige naafkonfigurasie. Dit is gedoen deur ’ n vergelyking van vier naafkonfigurasies: ’ n ronde naaf, ’ n boks naaf, en twee skyf nawe. Berekenings vloeimeganika modellering, met behulp van die oopbronsagteware OpenFOAM, word gebruik om elke naaf te simuleer. BlockMesh word gebruik om die rooster te bou. Daar word gevind dat die impak op die werkverrigting as gevolg van die naafkonfigurasie afhanklik is van die volumetriese vloeitempo deur die waaier. By bo-ontwerp punt volumetriese vloeitempo besorg die boks naaf die beste werksverrigting met ’n styging van 9.5 % in totale-tot-statiese drukverhoging en ’n 5.1 % punt vehoging in totale-tot-statiese doeltreffendheid, in vergelyking met die ronde naaf. In kontras, bied die sentrale skyf naaf ’n 8.4 % verbetering in totale-tot-statiese drukverhooging en ’n 5.7 % punt verbetering in die totaletot- statiese doeltreffendheid in vergelyking met die ronde naaf, by 62.5 % van die ontwerpsvloeitempo. By die ontwerpsvloeitempo toon die ronde en boks naaf soortgelyk aan, en doen beter as die skyf nawe.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/108317
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