Spelling suggestions: "subject:"dans (machinery) -- aperformance."" "subject:"dans (machinery) -- _eerformance.""
1 |
Personal fans for improving comfortGough, Helen M January 2011 (has links)
Typescript (photocopy). / Digitized by Kansas Correctional Industries
|
2 |
Comfort and cooling with box fansRosen, Eric R January 2011 (has links)
Typescript (photocopy). / Digitized by Kansas Correctional Industries
|
3 |
An evaluation of a design method for mixed flow fansDu Toit, Jacques H. (Jacques Hendrik) 03 1900 (has links)
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.
|
4 |
The effectiveness of axial flow fans in a-frame plenumsVenter, Sarel Jacobus, Kroger, D. G. 03 1900 (has links)
Thesis (PhD (Mechanical and Mechatronic Engineering)--University of Stellenbosch, 1990. / 260 leaves printed single pages, preliminary pages i-xxi and numbered pages Chapter 1/1.1-1.3, Chapter 2/2.1-2.17, Chapter 3/3.1.1-3.10, Chapter 4/4.1-4.18, Chapter 5/5.1-5.3, References pages R.1-R.7, Appendix A pages A.1-A.34, Appendix B pages B.1-B.34, Appendix C pages C.1-C.26, Appendix D pages D.1-D.16, Appendix E pages E.1-E.30, Appendix F pages F.1-F.39. Includes bibliography, list of tables, figures and symbols. / Digitized at 600 dpi grayscale to pdf format (OCR), using a Bizhub 250 Konica Minolta Scanner. / ENGLISH ABSTRACT: The ultimate goal of this project is to ensure a better understanding of the governing
mechanisms present when flow distorting components are installed in close proximity of
an axial flow fan.
The effect of different parameters on the operation of axial flow fans is investigated. These
parameters are divided into flow enhancing and flow reduction effects. The performance
of an axial flow fan can be enhanced by changing the tip clearance, by adding a solid
disc to the hub of the fan or by varying the number of fan blades. Flow reductions are
caused by components such as inlet grids, walkways and their supporting structures, heat
exchangers and windwalls.
The effects of flow enhancing components are measured and compared to the results of
other authors. The sensitivity of these effects to parameters such as the type of fan rotor
and the specific system in which the rotor is installed is highlighted.
The system effect (the interaction between the fan rotor and flow resistances in close
proximity of each other) of individual components, as well as the combination of different
components, is predicted both theoretically and experimentally. These predictions are
compared to measured data relevant to the components in an installation where the system
effects are present. The results are correlated to the kinetic energy flux coefficient of the
flow at different locations within the installation.
Experimental data obtained from a full scale unit (inlet shroud diameter of 9,216 m) are
used to compare to scaled data from the model (inlet shroud diameter of 1,542 m). The
hub to tip ratio of the axial flow fans investigated is 0,15.
The most important conclusions are that the performance of the type of axial flow fan
under investigation can be improved by reducing its tip clearance and by installing a solid
disc to the downstream side of the rotor. An increase in the number of blades of the fan
leads to only marginal improvements in the fan performance. The overall performance of
the system can also be improved by removing some of the flow resisting components, or
by changing their relative positions. All these conclusions are based on the assumption
that the power input to the fan rotor remains constant. / AFRIKAANSE OPSOMMING: Die uiteindelike doel van hierdie projek is om te verseker dat die beherende meganismes wat
teenwoordig is wanneer vloeiversteurende komponente in die nabyheid van 'n aksiaalwaaier
geinstalleer word, beter verstaan word.
Die effek van verskillende parameters op die werkverrigting van aksiaalwaaiers word ondersoek.
Hierdie parameters word verdeel in vloeiverbeterings- en vloeiverminderingseffekte.
Die werkverrigting van 'n aksiaalwaaier kan verbeter word deur die lempuntspeling te verstel,
deur 'n soliede skyf aan die naaf van die waaierrotor te installeer, of deur die aantal
lemme te verander. Die vloeiverminderings word veroorsaak deur inlaatsiwwe, loopvlakke
en hul ondersteuningsstrukture, warmteruilers en windwande.
Die effekte van vloeiverbeteringskomponente word gemeet en vergelyk met die resultate
van ander outeurs. Die sensitiwiteit van hierdie effekte op parameters soos die tipe rotor
en die spesifieke stelsel waarin die rotor geinstalleer is, word uitgelig.
Die stelseleffek (die interaksie tussen die rotor van die waaier en vloei weerstande wat
naby mekaar geinstalleer is) van individuele, sowel as 'n kombinasie van verskillende
komponente, word teoreties en eksperimenteel voorspel. Hierdie voorspellings word dan
vergelyk met eksperimentele data wat van toepassing is op die komponente in 'n installasie
waar stelseleffekte voorkom. Die resultate word gekoppel aan die kinetiese energievloedkoeffisient
van die vloei by verskillende posisies binne die installasie.
Eksperimentele data, verkry vanaf 'n volskaaleenheid (inlaatmondstukdiameter van 9,216 m),
word met die geskaleerde data van die model (inlaatmondstukdiameter van 1,542 m) vcrgelyk.
Die naaf- tot hulsverhouding van die aksiaalwaaiers wat ondersoek word is 0,15.
Die belangrikste gevolgtrekkings is dat die werkverrigting van die tipe aksiaalwaaier wat
ondersoek word verbeter kan word deur die lempuntspeling te verminder en deur 'n soliede
skyf te installeer by die stroomaf kant van die rotor. 'n Toename in die aantal lemme
van die waaier lei slegs tot marginale verbeterings in die werkverrigting van die waaier.
Die totale werkverrigting van die stesel kan ook verbeter word deur sommige vloeiweerstandskomponente
te verwyder, of deur hulle relatiewe posisies te verander. Al hierdie gevolgtrekkings is gebasseer op die aanname dat die drywingsinset na die waaierrotor konstant
bly.
|
5 |
The correlation of randomness with high tip losses in an axial flow fan stageAlday, John Hane 24 November 2009 (has links)
The results of a test program incorporating a dual hot wire aspirating probe to radially survey the by-pass duct downstream of an axial flow fan stage are presented. The probe measures time resolved total temperature and total pressure from which isentropic efficiency is calculated. The objective was to provide time resolved data to further the understanding of the flow and aid in determining the source of high losses located near the rotor tip. A technique for quantifying randomness of an unsteady flow is developed, and the randomness of the surveyed flow is shown to correlate with the losses. A new method of ensemble averaging instantaneous data is presented which produces an identifiable blade passage profile even in a random flowfield where traditional techniques often fail. Time averages of the aspirating probe data are shown to agree with conventional steady-state measurements within the experimental uncertainties. Unsteady features seen in the data are compared to similar features noted in the literature, and contour plots of the ensemble averaged data and unsteady fluctuations are presented. / Master of Science
|
6 |
Fan noise reduction from a supersonic inletNuckolls, William E. 22 August 2009 (has links)
A series of experiments was conducted to investigate the radiation of fan noise through a supersonic inlet. A scaled-down model of an axisymmetric, mixed-compression, supersonic inlet (P-inlet) was used in conjunction with a 10.4 cm (4.1 in) diameter turbofan engine simulator as the noise source. The tests were conducted at an outdoor facility under static conditions. An attempt is made to reduce the fan noise radiated in the forward sector by modifying the auxiliary inlet doors. The modified doors are designed to reduce the inlet distortion to the fan face. In addition, the new design also uses a converging flow passage in the auxiliary doors in order to take advantage of the noise attenuation due to the choking effect. Both aerodynamic and acoustic measurements are taken in the experiments. The results show that when compared to the original design, the modified auxiliary inlet doors are successful in reducing distortion to the fan face, and that the blade passing frequency tone has been decreased by an average of 6 dB in the forward sector. Results from the closed auxiliary inlet door case are also presented to provide additional comparisons. / Master of Science
|
7 |
Die invloed van versteurde inlaatvloeipatrone op aksiaalwaaiersVisser, J. G. J. 12 1900 (has links)
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.
|
8 |
Simulating the effect of wind on the performance of axial flow fans in air-cooled steam condenser systemsFourie, Neil 12 1900 (has links)
Thesis (MEng) -- Stellenbosch University, 2014. / ENGLISH ABSTRACT: The use of air-cooled steam condensers (ACSCs) is the preferred cooling
method in the chemical and power industry due to stringent environmental and
water use regulations. The performance of ACSCs is however highly dependent
on the influence of windy conditions. Research has shown that the presence of
wind reduces the performance of ACSCs. It has been found that cross-winds
(wind perpendicular to the longest side of the ACSC) cause distorted inlet flow
conditions, particularly at the upstream peripheral fans near the symmetry
plane of the ACSC. These fans are subjected to what is referred to as '2-D' wind
conditions, which are characterised by flow separation on the upstream edge
of the fan inlets. Experimental investigations into inlet flow distortion have
simulated these conditions by varying the fan platform height. Low platform
heights resulted in higher levels of inlet flow distortion, as also found to exist
with high cross-wind speeds. This investigation determines the performance of
various fan configurations (representative of configurations used in the South-
African power industry) subjected to distorted inlet flow conditions through
experimental and numerical investigations. The similarity between platform
height and cross-wind effects is also investigated and a correlation between
system volumetric effectiveness, platform height and cross-wind velocity is
found. / AFRIKAANSE OPSOMMING: Die gebruik van lugverkoelde stoom kondensors (LVSK's) word verkies as
'n verkoelingsmetode in die chemiese- en kragvoorsieningsindustrie as gevolg
van streng omgewings- en waterverbruiksregulasies. Die werkverrigting van
LVSK's word egter grootliks beïnvloed deur die teenwoordigheid van wind.
Navorsing het gewys dat die teenwoordigheid van wind die werkverrigting van
LVSK's verminder. Daar was gevind dat kruiswinde (wind loodreg tot die
langste sy van die LVSK) versteurde inlaat vloeitoestande veroorsaak, veral
by waaiers wat aan die stroomop kant van die LVSK naby die simmetrievlak
geleë is. Hierdie waaiers word blootgestel aan na wat verwys word as
'2-D' windtoestande wat gekenmerk word deur vloeiwegbreking wat plaasvind
by die stroomop rand van die waaierinlate. Eksperimentele ondersoeke van
inlaat vloeiversteurings het hierdie toestande gesimuleer deur die waaier platformhoogte
te verstel. Lae platform hoogtes het gelei tot hoër vlakke van
inlaat vloeiversteuring, soortgelyk aan wat gevind word met hoë kruiswindsnelhede.
Hierdie ondersoek gebruik numeriese en eksperimentele metodes om die
werkverrigting van verskeie waaierkon gurasies (verteenwoordigend van kon-
gurasies wat gebruik word in die Suid-Afrikaanse kragvoorsieningsindustrie)
wat blootgestel word aan versteurde inlaat vloeitoestande te bepaal. Die ooreenkoms
tussen platformhoogte en kruiswind e ekte word ook ondersoek en
'n korrelasie tussen die sisteem volumetriese e ektiwiteit, platformhoogte en
kruiswindsnelheid word bepaal.
|
Page generated in 0.0836 seconds