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Numerical analysis of windscreen effects on air-cooled condenser fan performance and blade loading

dc.contributor.advisorOwen, Michaelen_ZA
dc.contributor.advisorMuiyser, Jacquesen_ZA
dc.contributor.authorVenter, Adam Johnen_ZA
dc.contributor.otherStellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.en_ZA
dc.date.accessioned2020-02-26T10:53:46Z
dc.date.accessioned2020-04-28T12:24:28Z
dc.date.available2020-02-26T10:53:46Z
dc.date.available2020-04-28T12:24:28Z
dc.date.issued2020-03
dc.identifier.urihttp://hdl.handle.net/10019.1/108191
dc.descriptionThesis (MEng)--Stellenbosch University, 2020.en_ZA
dc.description.abstractENGLISH ABSTRACT: Wind is recognized as the most significant challenge facing air-cooled condenser (ACC) performance. Wind exacerbates the flow distortions that occur at the fan unit inlets, which aggravates fan performance losses and blade vibrations. Consequently, multiple wind effect mitigation strategies have been formulated, of which the installation of porous peripheral windscreens that span along and beneath the perimeter of an ACC fan platform is included. However, the benefit of peripheral windscreens is not widely known and the available literature surrounding their impact is inconsistent. Some studies suggest that windscreens offer an increase in perimeter fan performance, while others suggest the contrary or that windscreens are mostly beneficial in reducing blade loading. This study, therefore, undertook to construct and validate numerical techniques that can be used to explore the mechanisms that determine the effect of peripheral windscreens on both ACC fan performance and dynamic blade loading. The ensuing numerical model replicates an experimental ACC fan row test facility and is shown to be able to deliver quantitative assessment of fan row performance effects and qualitative assessment of dynamic blade loading effects. For the experimental facility characteristics, representative of an ACC of low platform height, the model indicates that the installation of peripheral windscreens primarily degrades fan row performance. Based on fan row volumetric effectiveness, a maximum performance deficit of 19% (expressed as a percentage difference relative to the no-screen scenario) accompanies the installation of a windscreen (50% solidity material) covering 50% of the peripheral inlet area at a platform height wind speed of 6.6 m/s (approximated full-scale wind speed of 10 m/s). Conversely, the model shows that the peripheral windscreens offer favourable reductions in edge fan dynamic blade loading. The reduction in fan row performance is attributed to the development of a low pressure wake behind the screens and the favourable reduction in dynamic loading to the creation of more uniform and symmetric velocity profiles through the edge fan’s inlet. Moreover, the effective platform height of the experimental facility model is adapted to offer a preliminary assessment of the influence of platform height on the windscreen effects. Resultantly, it appears that the windscreen blade loading effects are largely independent of platform height, while fan row performance effects are shown to exhibit a more definite dependence. It is uncovered that favourable enhancement of fan row performance is attainable once the configuration of the screen and platform height is able to deflect the accelerated flow region, which forms beneath the screen, past the fan row completely; a scenario more easily attained at lower wind speeds with taller platform heights. The numerical techniques described and validated in this study are wellpositioned for adoption into future wind effect simulation studies, particularly full-scale simulation.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Wind word gereken as die belangrikste uitdaging wat lugverkoelde kondensors (aircooled condenser (ACC)) se werkverrigting beïnvloed. Wind vererger die vloeivervormings wat by die inlaat van die waaier-eenheid voorkom, wat die waaier se werksverrigting-verlies en die vibrasies van die lemme vererger. Gevolglik is verskeie strategieë vir die vermindering van die effek van die wind geformuleer, waarvan die installasie van poreuse perifere windskerms wat langs en onder die buitegrense van 'n ACC-waaierplatform ingesluit is. Die voordeel van ’n perifere windskerm is egter nie algemeen bekend nie en die beskikbare literatuur rondom die impak daarvan is teenstrydig. Sommige studies dui daarop dat windskerms 'n toename in die werkverrigting van die waaier teen die buitegrense veroorsaak, terwyl ander die teendeel voorstel, of dat windskerms meestal voordelig is om die las op die lemme te verminder. Hierdie studie het dus onderneem om numeriese tegnieke saam te stel en te verifieer wat gebruik kan word om die meganismes te ondersoek wat die effek van perifere windskerms op beide ACC-waaierprestasie en dinamiese lembelasting bepaal. Die gevolglike numeriese model kopieer 'n eksperimentele ACC-waaierry-toetsfasiliteit en daar word getoon dat dit kwantitatiewe assessering van die waaierry-prestasie-effekte en die kwalitatiewe assessering van dinamiese lembelasting-effekte kan lewer. Vir die eienskappe van die eksperimentele fasiliteit, wat verteenwoordigend is van 'n ACC met 'n lae platformhoogte, dui die model aan dat die installering van die perifere windskerm hoofsaaklik die waaierry-prestasie benadeel. Op grond van die effektiwiteit van die waaierrye, gaan 'n maksimum prestasietekort van 19% (uitgedruk as 'n persentasieverskil relatief tot die geen-skermscenario) gepaard met die installering van 'n windskerm wat 50% van die perifere inlaatarea bedek op 'n platformhoogte windspoed van 6.6 m/s (benaderde volskaalse windsnelheid van 10 m/s). Omgekeerd toon die model dat die perifere windskerm gunstige verlagings bied vir dinamiese lembelasting op die randwaaier. Die vermindering in die waaierry-prestasie word toegeskryf aan die ontwikkeling van 'n laedruk-sone agter die skerms en die gunstige afname in dinamiese lading om meer eenvormige en simmetriese snelheidsprofiele deur die inlaat van die randwaaier te skep. Die effektiewe platformhoogte van die eksperimentele fasiliteitsmodel word aangepas om 'n voorlopige beoordeling van die invloed van die platformhoogte op die windskerm effekte aan te bied. Gevolglik blyk dit dat die lembelasting van die windskerm grootliks onafhanklik van die hoogte van die platform is, terwyl die prestasie-effekte van die waaier 'n duideliker afhanklikheid vertoon. Dit word duidelik dat 'n gunstige verbetering van die waaierry-werkverrigting gekry word sodra die skerm en die platformhoogte die versnelde vloeigebied, wat onder die skerm vorm, langs die waaier ry heeltemal kan wegbuig; 'n scenario wat makliker gerealiseer kan word by laer windsnelhede met hoër platformhoogtes. Die numeriese tegnieke wat in hierdie studie beskryf en bekragtig is, is goed geposisioneer om in toekomstige windeffek-simulasie studies gebruik te word, veral op volskaalse simulasie.af_ZA
dc.format.extentxvi, 117 leaves : illustrations (some color)
dc.language.isoenen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.subjectAir-cooled condensersen_ZA
dc.subjectFans (Machinery)en_ZA
dc.subjectBlade loadingen_ZA
dc.subjectWindscreens -- Aerodynamicsen_ZA
dc.subjectANSYS (Computer system)en_ZA
dc.subjectNumerical analysisen_ZA
dc.subjectUCTDen_ZA
dc.titleNumerical analysis of windscreen effects on air-cooled condenser fan performance and blade loadingen_ZA
dc.typeThesisen_ZA
dc.description.versionMastersen_ZA
dc.rights.holderStellenbosch Universityen_ZA


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