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Continuous processing of vesiculated beadsGous, Karen 04 1900 (has links)
Thesis (MScIng)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: Titanium dioxide (TiO2) is extensively used as pigment in paint formulations, but due
to the high cost associated with it, along with its’ depleting natural resources, paint
manufacturers are seeking substitutes that can at least partially replace this pigment.
Vesiculated beads have been successfully used in the past as a replacement for the
TiO2-pigment. These beads are spherical polymer particles that contain a multitude of
aerated micro voids within the polymer shell. The aerated voids cause effective
scattering of light inside the particles, presenting the beads with a white appearance.
It was found that low levels of TiO2 could be encapsulated in the particles as a means
of increasing the whiteness and hiding power of the beads in the wet- and dry state.
Because the beads are about two-thirds air by volume and contain only small amounts
of TiO2, it also presents a method of reducing the formula cost.
The beads are produced with an emulsification process where by an organic phase
containing unsaturated polyester resin and styrene monomer is emulsified within an
aqueous phase. This phase consists mainly of de-ionised water and stabilisers that
assist in forming a stable emulsion of organic droplets in the continuous aqueous
phase. A polyamine is also added to the system to achieve the uptake of water
droplets inside the organic phase. It is this water that is replaced with air when it
evaporates from the beads upon drying, and leaves the particles with air-filled
vesicles.
Emulsification is currently achieved locally with the use of a Cowles disperser system
or an emulsion reactor set-up with the application of a specified stirring speed for a
specific period of time. These stirring specifications are manipulated so that the
organic globules are subjected to a specific shear rate and consequently are broken
down to the required particle size. The polymeric reaction is initiated with the
addition of a free-radical initiator and redox activator and the product is left overnight
to allow completion of the reaction and subsequent formation of slurry containing
solid polymer particles. In this study, homogenisation was investigated as a means of emulsifying and
producing vesiculated beads in a continuous process. Homogenisation is defined as
the act of breaking down globules into smaller particles under pressure and produces a
product with evenly dispersed (homogeneous) fine particles. This process could
therefore also be used to produce particles with a smaller average particle size than
those obtained by the existing Cowles- and emulsion reactor manufacturing processes.
These batch processes produce vesiculated beads with an average particle size
between 3 and 10 micron on industrial scale. With the incorporation of the
homogeniser in a continuous process it would be possible, not only to produce
particles in the order of 1 micron required for the addition to gloss paint, but it would
also have the added advantages of easy cleaning, higher production rates and the use
of smaller equipment.
The most important operating parameters when using a homogenisation system were
determined using a laboratory scale homogeniser set-up. These parameters included
the geometry of the internals of the homogeniser, the number of passes and the flow
rate. From the information and results obtained from the batch experiments a semicontinuous
bench-scale homogeniser set-up was designed. This experimental set-up
consisted of a homogeniser, high-pressure pump, continuous feed section for the
initiator and a loop-reactor equipped with a heating mantle to facilitate continuous
curing of the product. Vesiculated beads with properties similar to those obtained by
the existing batch processes, but with an average particle size in the order of 1 micron,
were produced successfully with this semi-continuous set-up. Although the beads
were not entirely cured after leaving the loop-reactor it is believed that with increased
heating and an increase in the length of the reactor, this problem can be addressed.
The results obtained with the semi-continuous process could be used in future in the
design and construction of a continuous pilot plant for the production of vesiculated
beads. / AFRIKAANSE OPSOMMING: Titaandioksied (TiO2) word in groot hoeveelhede as pigment in verf gebruik, maar as
gevolg van die hoë koste van hierdie pigment en die uitputting van die natuurlike
bronne, is verfvervaardigers op soek na alternatiewe.
Polimeerpartikels met lugholtes daarin vasgevang, is in die verlede suksesvol as
plaasvervanger vir die pigment gebruik. Hierdie partikels is sferiese
polimeerpartikels met ‘n menigte klein lugholtes wat effektiewe verstrooiing van lig
binne die partikels veroorsaak. Dit verskaf aan die partikels ‘n wit voorkoms en daar
is gevind dat klein hoeveelhede TiO2 binne die partikels vasgevang kan word om die
witheid in die nat- en droë fase te verhoog. Omdat die partikels uit ongeveer twee
derdes lug bestaan en slegs klein hoeveelhede TiO2 bevat, word ‘n vermindering in
produksiekoste verkry as dit in verf gebruik word.
Die polimeerpartikels word geproduseer met ‘n emulsifiseringsproses waarby ‘n
organiese fase, bestaande uit onversadigde poliëster en stireen monomeer, in ‘n
waterfase geëmulsifiseer word. Laasgenoemde bestaan hoofsaaklik uit
gedeïoniseerde water en stabiliseerders wat die vorming van ‘n stabiele emulsie van
organiese druppels in die kontinue waterfase bewerkstellig. ‘n Poli-amien word ook
by die sisteem gevoeg om die organiese fase in staat te stel om water op te neem. As
hierdie water dan van die partikels verdamp wanneer dit droog word, word dit deur
lug verplaas en laat dit die partikels met ‘n menigte lugholtes agter.
In Suid-Afrika, word emulsifisering tans bewerkstellig deur die gebruik van ‘n
“Cowles” menger of ‘n emulsiereaktorsisteem waar ‘n spesifieke roerspoed vir ‘n
vasgestelde tydperk aangewend word. Hierdie roerspesifikasies word so gekies dat ‘n
bepaalde skuifkrag op die organiese druppels uitgeoefen word en dit dus tot die
verlangde partikelgrootte opgebreek word. As die bepaalde partikelgrootte bereik is,
word die reaksie geïnisieer deur die byvoeging van ‘n vry-radikaal inisieerder en ‘n
redoksaktiveerder. Die produk word dan oornag gelaat sodat die reaksie voltooi kan
word en die soliede polimeerpartikels binne die kontinue waterfase gevorm kan word. Tydens hierdie studie is homogenisering ondersoek as ‘n moontlike metode om
emulisifisering te bewerkstellig en sodoende die polimeerpartikels te produseer.
Homogenisering word gedefinieer as ‘n proses waartydens partikels afgebreek word
onder hoë druk en gevolglik lei dit tot die vorming van ‘n produk bestaande uit klein
partikels uniform versprei deur die produk. Die moontlikheid bestaan dus dat
homogenisering in ‘n proses gebruik kan word om kleiner partikels te produseer as
wat moontlik is met die bestaande Cowles- of emulsiereaktor prosesse. Hierdie
enkelladingsprosesse word gebruik om polimeerpartikels met ‘n gemiddelde
partikelgrootte tussen 3 en 10 mikron op industriële skaal te produseer. Deur die
homogeniseerder in ‘n kontinue proses te gebruik sal so ‘n proses gebruik kan word
nie net om partikels met ‘n grootte van ongeveer 1 mikron (noodsaaklik vir glansverf)
te produseer nie, maar hou dit ook verdere voordele in soos hoër produksie, kleiner
toerusting en die gemak waarmee so ‘n sisteem skoongemaak kan word.
‘n Laboratorium-skaal enkelladings homogeniseerder is gebruik om die belangrikste
bedryfsparameters van ‘n homogeniseringsisteem te bepaal. Hierdie parameters sluit
in die geometrie van die interne dele van die homogeniseerder, asook die vloeitempo
en die aantal deurgange deur die homogeniseeder. Die resultate van die enkelladings
eksperimente is gebruik om ‘n semi-kontinue loodsaanleg skaal opstelling met ‘n hoë
druk pomp, homogeniseerder, kontinue toevoer seksie vir die inisieërder en ‘n
kontinue buisreaktor om die volledige verloop van die reaksie te verseker, te
ontwikkel.
Polimeerpartikels gevul met lugholtes is geproduseer met bogenoemde proses en
produkeienskappe vergelykbaar met die van die bestaande enkelladingsprosesse is
verkry. Die enigste verskil tussen die produkeienskappe van die verskillende
prosesses was die gemiddelde partikelgrootte met die partikels geproduseer met die
homogeniseerderproses in die order van 1 mikron en die van die ander prosesse veel
groter.
Die resultate verkry met die semi-kontinueproses sal in die toekoms gebruik word vir
die ontwerp en bou van ‘n ten volle kontinue loodsaanleg.
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Characterisation and development of antifouling coatings for metal surfaces in aquatic environmentsVolschenk, Mercia 04 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Biofouling in cooling water systems lead to several problems resulting in reduced efficiency and
financial losses. Antifouling coatings present an environmental friendly solution to prevent
biofouling alternatively to the current use of toxic chemicals in cooling water systems.
In this study biofilm growth in a cooling water system was simulated in a modified flow cell system
to evaluate industrial antifouling coatings and biocide-enriched coatings as potential antifouling
coatings for metal surfaces. The design of a novel antifouling coating was also attempted. Firstly,
analytical methods for biofilm monitoring to evaluate selected antifouling coatings and biocides
were optimised. Pseudomonas sp. strain CT07 was selected to grow biofilms in the biofilm studies.
A metal alloy of stainless steel and mild steel (3CR12) showed no corrosion after a 24 h biofilm
growth and was selected as metal surface for the biofilm growth discs. Sonification for 5 min was
determined as the optimum biofilm removal method from the growth discs. After biofilm removal
the metal growth discs were stained with the LIVE/DEAD® BaclightTM Bacterial Viability kit.
Visualisation by confocal laser scanning microscopy and flow cytometry revealed auto
fluorescence signals from metal discs that hindered quantitative and qualitative analysis of the
metal substrate. The use of Pseudomonas sp. strain CT07::gfp to grow biofilms on the metal
growth discs and the exclusion of the stain SYTO9 from the LIVE/DEAD® BaclightTM Bacterial
Viability kit reduced auto fluorescence signals from the metal discs. The industrial coatings
containing quaternary ammonium salt (QAC), triclosan (TC) and copper oxide (CUO) respectively,
showed the highest antimicrobial activity in the disc diffusion test. The minimum inhibition
concentrations for silver nitrate (SN) and copper sulphate (CS) were 432 ppm and 160 ppm
respectively. A minimum of 6.25 % of furanone solution (FR) was biocidal in the dilution
susceptibility test.
Secondly, the metal growth discs were coated respectively with the three selected industrial
coatings QAC, TC and CUO and the epoxy biocide-enriched coatings SN, CS and FR and
chemically characterised before and after exposure to biofilm formation. The antifouling activity of
these coatings was also characterized. Growth media inoculated with Pseudomonas sp strain
CT07::gfp was circulated through the modified flow cell system via a multichannel peristaltic pump
for 48 h before the coated metal discs were removed and washed to perform chemical or
antifouling analysis. All the industrial coatings and biocide enriched epoxy coatings complied with
the thermal stability requirements of a cooling water system. Scanning electron microscopy (SEM)
imaging and Energy dispersive X-ray spectroscopy (EDX) analysis confirmed that the adhesion
properties of industrial coatings TC and QAC in aqueous environments were insufficient and that
the copper and silver ions leached out of the biocide-enriched epoxy coatings.
The qualitative analyses of the attachment of bacteria on the surfaces of both the industrial and
biocide enriched epoxy coatings was confirmed by SEM, CLSM. The attached bacteria were removed and analysed quantitatively through plate counts and flow cytometry. None of the
industrial coatings or the biocide incorporated epoxy coatings that were used in this study would
therefore be efficient for the use on metal surfaces in cooling water systems.
Thirdly, several approaches were followed to synthesise a poly(styrene-alt-maleic anhydride)
(SMA) coating, chemically bind a furanone derivative, 2,5-dimethyl-4-hydroxy-3-(2H)-furanone, to
the polymer back bone of the SMA coating for the application as an antifouling coating for cooling
water systems. The synthesis of SMA was confirmed through 1H NMR and SEC and the synthesis
of tert-butyl 2-(2-hydroxyethoxy) ethylcarbamate and 4-(2-(2-(tert-butoxycarbonyl)ethoxy)ethoxy)-4-
oxobutanoic acid was confirmed through 1H NMR and ES-MS+. The synthesis of the end
furanone derivative product could however not be achieved. / AFRIKAANSE OPSOMMING: Bio-aanpaksels in waterverkoelingsisteme veroorsaak talle probleme wat lei tot verminderde
doeltreffendheid en finansiële verliese. Antimikrobiese oppervlakbedekkings verskaf ‘n
omgewingsvriendelike oplossing om bio-aanpaksels te voorkom en ‘n alternatief vir die huidige
gebruik van giftige chemikalieë in waterverkoelingsisteme.
Biofilm groei in waterverkoelingsisteme was nageboots in ‘n gewysigde vloeiselsisteem om
industriële aanpakwerende en biopsied bevattende antimikrobiese oppervlakbedekkings as
potensiële aanpakwerende beskermingslae vir metaaloppervlaktes te evalueer. Die ontwerp van ‘n
nuwe aanpakwerende beskermingslaag is ook ondersoek. Eerstens is analitiese
moniteringsmetodes vir bio-aanpaksels op geselekteerde aanpakwerende antimikrobiese
oppervlakbedekkings en biosiedes geoptimiseer. Pseudomonas sp. stam CT07 was verkies om
bio-aanpaksels te simuleer gedurende hierdie studie. ‘n Metaalalooi van vlekvrye staal en sagte
staal (3R12) het geen korrosie getoon na 24 uur se groei van bio-aanpaksels nie en is vir hierdie
rede gebruik as metaal vir die bio-aanpaksel groeiplate. Dit was vasgestel dat sonifisering die
optimale verwyderingsmetode vir groeiplate was. Na verwydering van bio-aanpaksels was die
metaal groeiplate bedek met die LIVE/DEAD® BaclightTM bakteriële lewensvatbaarheid-toestel.
Visualisering deur middel van konfokale mikroskopie en vloeisitrometrie het outofluoreserende
seine vanaf die metaal groeiplate onthul wat kwantitatiewe en kwalitatiewe analise van die metaal
substraat verhinder het.
Die gebruik van Pseudomonas sp. stam CT07:gfp om bio-aanpaksels te kweek op metal plate en
die uitsluiting van SYT09 van die LIVE/DEAD® BaclightTM bakteriële lewensvatbaarheid-toestel,
het die outofluoreserende seine van die metaalskywe verminder. Industriële beskerminglae, wat
onderskeidelik Kwaternêre ammonium sout (QAC), triclosan (TC) en koperoksied (CUO) bevat, het
die hoogste antimikrobiese aktiwiteit in die skyf-diffusie toets getoon. Die minimum inhibisiekonsentrasies
vir silwernitraat (SN) en kopersulfaat (CS) was onderskeidelik 432 dpm en 160 dpm.
‘n Minimum konsentrasie van 6.25% van die furanoonoplossing (FO) is geklassifiseer as ‘n biosied
in die oplossingstoets.Tweedens was die metaal groei-skywe bedek met drie industriële
beskermingslae QAC, TC en CUO en die epoksie-biosied-verrykte lae SN, CS en FR en chemiesgekarakteriseerd
voor en na die vorming van bio-aanpaksel. Die karaktereienskappe van die
aktiwiteit van die beskermingslae was ook vasgestel. Opgeloste triptiese soja sop vermeng met
Pseudomonas sp strain CT07: gfp was gesirkuleer in die gemodifiseerde vloeisel deur ‘n
multikanaal peristaltiese pomp vir 48 uur voordat die beskermde metaalskywe verwyder en gewas
is om chemiese en aanpakwerende analise uit te voer. Al die industriële beskermingslae en
biosied-verrykte epoksie-beskermingslae het aan die vereistes van termiese stabiliteit van ‘n
waterverkoelingsisteem voldoen. Skandeer elektronmikroskopie (SEM) en X-straal spektroskopie
(EDX) analise het aangetoon dat die aantrekkingseienskappe van industriële beskermingslae TC en QAC in waterige oplossings onvoldoende was en dat die koper- en silwerione uit die biosiedverrykte
epoksie-resin beskermingslae diffundeer. Die kwalitatiewe analise van die aanpaksel van
bakterieë op die oppervlaktes van beide industriële en biosied -verrykte epoksie-beskermingslae
was bevestig deur SEM en CLSM. Die aangepakte bakterieë was verwyder en kwantitatief
geanaliseer deur middel van plaattellings en vloeisitrometrie. Nie een van die industriële
beskermingslae of die biosied-bevattende epoksie beskermingslae wat in hierdie studie gebruik is,
is dus gepas vir gebruik op metaaloppervlaktes in waterverkoelingsisteme nie.
Derdens was verskeie pogings aangewend om ‘n poli(stireen-alt-maleic anhidried) (SMA)
beskermingslaag chemies te bind tot ‘n furanoon afgeleide 2.5-demitiel-4-hidroksie-3-(2H)-
furanoon, tot die polimeer-ruggraat van die SMA beskermingslaag vir aanwending as ‘n
aanpakwerende beskermingslaag vir waterverkoelingsisteme. Die sintese van SMA was bevestig
deur 1H NMR en SEC en die sintese van tert-butyl 2-(2-hirdoksie-etoksie) etielkarbamaat en 4-(2-
(2-(tert-butoksiekarboniel)etoksie)etoksie)-4-oksobutanoiesesuur was bevestig deur 1H NMR en
ES-MS+. Die sintese van die uiteindelike afgeleide furanoon kon egter nie behaal word nie.
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Identification and characterization of additives in colourants by advanced analytical techniquesMaku, Lebogang Jennifer 12 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Various types of anionic, non-ionic, cationic and zwitterionic additives are used in the coatings industry for the production of paints and colourants. These additives are added to enhance properties such as stabilization of pigment dispersions, wetting of pigments and improvement of open time and freeze/thaw stability. Very often the exact chemistry of these commercial additives is unknown and this is a limitation for new product developments. The identification and characterization of these multi-component polymeric materials continues to be a challenging task. This research presents the use of various advanced analytical techniques to identify and characterize commercial additives that are used in a multi-component colourant formulation. The focus of the present study is on additives that are based on poly(ethylene glycol) (PEG). The molar mass distribution of PEG-based additives was determined with liquid chromatography coupled to mass spectrometry (LC-MS) using solvent gradient elution and at critical conditions of adsorption (LCCC) of PEG. Using the combination of LC-MS, proton nuclear magnetic resonance spectroscopy (1H NMR), pyrolysis gas chromatography (py-GC-MS) and Fourier transform infrared spectroscopy in attenuated total reflectance mode (FTIR-ATR), different additives were identified in terms of the number and type of polymer end groups. The efficiency of the extraction and identification protocol was demonstrated for a blend of additives in a colourant formulation. / AFRIKAANSE OPSOMMING: Verskeie tipes anioniese, nie-ioniese, kationiese en zwitterioniese bymiddels word gebruik in die bedekking nywerheid vir die vervaardiging van verwe en kleurmiddels. Hierdie bymiddels word bygevoeg om sekere eienskappe, soos die stabilisering van pigment dispersie, benatting van pigmente en die verbetering van ope tyd en vries/dooi stabiliteit te versterk. Dikwels is die presiese chemie van hierdie kommersiële bymiddels onbekend en het dit ʼn beperking vir nuwe produk ontwikkeling tot gevolg. Die identifisering en karakterisering van hierdie meer-komponent polimeriese materiaal duur voort om ʼn uitdagings te wees. Hierdie navorsingstudie stel voor die gebruik van verskeie tegnieke om kommersiële bymiddels te identifiseer en karakteriseer wat in meer-komponent kleurmiddel formulasies gebruik word. Die fokus is geplaas op bymiddels wat gebaseer is op poli(etileen glikol) (PEG). The molêre massa verdeling van PEG-gebaseerde bymiddels was bepaal met vloeistofchromatografie gekoppel tot massaspektrometrie (VC-MS) met die gebruik van oplosmiddel gradient eluasie en by kritiese toestande van adsorpsie (VCKT) van PEG. Deur die kombinasie van VC-MS, proton kern magnetiese resonansie spektroskopie (1H KMR), pirolisegaschromatografie (pir-GC-MS) en Fourier-transformasie infrarooi spektroskopie in verswakking totale refleksie modus (FTIR-VTR), is verskillende bymiddels geïdentifiseer in terme van die hoeveelheid en tipe polimeer eindgroep teenwoordig. Die doeltreffendheid van die ekstrahering en identifisering protokol is gedemonstreer vir ʼn mengel van bymiddels in ʼn kleurmiddel formulering.
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Mechanistic aspects of acylal hydrolysisLe, Vu Truong January 1996 (has links)
No description available.
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FRM AIRCON : What can be done to improve the personal protective equipment for auto body painters?Eriksson, Ruben January 2016 (has links)
The professional auto body painter works in an extreme environment, where the painter faces constant movement, ever-changing working situations and pressure to deliver a flawless paint job: the paint booth. The temperature in the paint booth is high, often around 30˚ Celsius. The floor is very hard, made of metal grid or concrete, and the painter usually has to move around a lot, at least 9 km per day. For this project I chose to focus on the painter’s work footwear as a major part of the personal protective equipment. My goal is to create a new standard in working shoes, specifically made for this environment and context. A comfortable shoe that could withstand heat, paint dust and wear. A shoe that is made for its users: the FRM AIRCON.
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Forgotten MemoriesPremeaux, Benjamin 01 January 2005 (has links)
Memories are experiences that are removed from our present time and space. The images I create are also removed; they are of a specific time and place, an instant or series of instances captured. The work I have produced in this program is an amalgamation of two artistic media, photography and paint. I choose to layer images to emphasize the complexity of experiences and to illustrate a sense of time. The combination of a mechanical and a handmade object emphasizes the intricacy of our experiences. What is revealed is a combination of color and image that creates multiple compositions within the whole. Layering paint with photography and sculpture allows me to continue to experiment and explore the variety of media that I find most interesting. I draw inspiration from many artists including Jackson Pollack, Willem DeKooning, Richard Diebenkorn, the Starn Twins, David Hockney and Frida Kahlo.These influences and my own interpretations are what makes my work my own.
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Heart of FleshMcSpadden, Joseph Aaron 01 January 2006 (has links)
In the past two years my paintings have fluctuated from figuration to abstraction. Dense surfaces, physical weight, and sense of touch have been dominant characteristics of my work. I have tried to animate oil paint by pushing it to the outer edges of the painting support and by using it to perform unorthodox tasks. I have stretched the limits of oil paint, creating works that reference flesh and the figure even while the forms remain amorphous and minimal. My work is a way for me to question the meaning of material and spiritual transformation.
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La réception de l'œuvre de Joaquín Sorolla de 1881 à 2009 / The reception of Sorolla's complete works, from 1881 to 2009Fauvey, Jordane 13 October 2012 (has links)
La thèse de M. Jordane Fauvey explore un siècle élargi de réception critique de l'ouvre du peintre espagnol Joaquin Sorolla (1863-1923) depuis sa première participation à l'Exposition Nationale de Madrid en 1881, jusqu'à la récente présentation en Espagnede sa dernière oeuvre majeure, Vision de Espaça, de 2007 à 2009. En exploitant comme source principale la collection de presse du Musée Sorolla de Madrid (4.068 articles), l'auteur situe la naissance médiatique de Sorolla en 1895, l'année de son premier succès parisien. Il retrace son parcours de "savonnier" dans les capitales européennes et met tout particulièrement en évidence le paradoxe suivant : Alors que sa peinture lumineuse et dynamique perce à l'étranger, elle est rejetée à Madrid. / Mr Jordan Fauvey's thésis explorés a large century of critical réception of the Spanish painter Joaquïn Sorolla's work tram his first participation to the National Exhibition in Madrid in 1 881 to the récent introduction of his lest major work, Vision of Spain, from2007 to 2009. Exploiting as principal source the press collection of the Sorolla Museum in Madrid (4.068 articles), the author situates Sorolla's mediatised birth in 1895,the year of his fîrst Parisian Success. He recountsh is way in the Europeanc apitale' salons and particularly highlights the following paradox: Although his bright and dynamic painting becomes famous abroad, ït is rejected in Maadrid.
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Experimental investigation of film cooling effectiveness on gas turbine bladesGao, Zhihong 15 May 2009 (has links)
The hot gas temperature in gas turbine engines is far above the permissible metal temperatures. Advanced cooling technologies must be applied to cool the blades, so they can withstand the extreme conditions. Film cooling is widely used in modern high temperature and high pressure blades as an active cooling scheme. In this study, the film cooling effectiveness in different regions of gas turbine blades was investigated with various film hole/slot configurations and mainstream flow conditions. The study consisted of four parts: 1) effect of upstream wake on blade surface film cooling, 2) effect of upstream vortex on platform purge flow cooling, 3) influence of hole shape and angle on leading edge film cooling and 4) slot film cooling on trailing edge. Pressure sensitive paint (PSP) technique was used to get the conduction-free film cooling effectiveness distribution. For the blade surface film cooling, the effectiveness from axial shaped holes and compound angle shaped holes were examined. Results showed that the compound angle shaped holes offer better film effectiveness than the axial shaped holes. The upstream stationary wakes have detrimental effect on film effectiveness in certain wake rod phase positions. For platform purge flow cooling, the stator-rotor gap was simulated by a typical labyrinth-like seal. Delta wings were used to generate vortex and modeled the passage vortex generated by the upstream vanes. Results showed that the upstream vortex reduces the film cooling effectiveness on the platform. For the leading edge film cooling, two film cooling designs, each with four film cooling hole configurations, were investigated. Results showed that the shaped holes provide higher film cooling effectiveness than the cylindrical holes at higher average blowing ratios. In the same range of average blowing ratio, the radial angle holes produce better effectiveness than the compound angle holes. The seven-row design results in much higher effectiveness than the three-row design. For the trailing edge slot cooling, the effect of slot lip thickness on film effectiveness under the two mainstream conditions was investigated. Results showed thinner lips offer higher effectiveness. The film effectiveness on the slots reduces when the incoming mainstream boundary layer thickness decreases.
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Experimental investigation of film cooling effectiveness on gas turbine bladesGao, Zhihong 15 May 2009 (has links)
The hot gas temperature in gas turbine engines is far above the permissible metal temperatures. Advanced cooling technologies must be applied to cool the blades, so they can withstand the extreme conditions. Film cooling is widely used in modern high temperature and high pressure blades as an active cooling scheme. In this study, the film cooling effectiveness in different regions of gas turbine blades was investigated with various film hole/slot configurations and mainstream flow conditions. The study consisted of four parts: 1) effect of upstream wake on blade surface film cooling, 2) effect of upstream vortex on platform purge flow cooling, 3) influence of hole shape and angle on leading edge film cooling and 4) slot film cooling on trailing edge. Pressure sensitive paint (PSP) technique was used to get the conduction-free film cooling effectiveness distribution. For the blade surface film cooling, the effectiveness from axial shaped holes and compound angle shaped holes were examined. Results showed that the compound angle shaped holes offer better film effectiveness than the axial shaped holes. The upstream stationary wakes have detrimental effect on film effectiveness in certain wake rod phase positions. For platform purge flow cooling, the stator-rotor gap was simulated by a typical labyrinth-like seal. Delta wings were used to generate vortex and modeled the passage vortex generated by the upstream vanes. Results showed that the upstream vortex reduces the film cooling effectiveness on the platform. For the leading edge film cooling, two film cooling designs, each with four film cooling hole configurations, were investigated. Results showed that the shaped holes provide higher film cooling effectiveness than the cylindrical holes at higher average blowing ratios. In the same range of average blowing ratio, the radial angle holes produce better effectiveness than the compound angle holes. The seven-row design results in much higher effectiveness than the three-row design. For the trailing edge slot cooling, the effect of slot lip thickness on film effectiveness under the two mainstream conditions was investigated. Results showed thinner lips offer higher effectiveness. The film effectiveness on the slots reduces when the incoming mainstream boundary layer thickness decreases.
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