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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Continuous processing of vesiculated beads

Gous, 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.
72

Characterisation and development of antifouling coatings for metal surfaces in aquatic environments

Volschenk, 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.
73

Identification and characterization of additives in colourants by advanced analytical techniques

Maku, 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.
74

Mechanistic aspects of acylal hydrolysis

Le, Vu Truong January 1996 (has links)
No description available.
75

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.
76

Forgotten Memories

Premeaux, 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.
77

Heart of Flesh

McSpadden, 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.
78

La réception de l'œuvre de Joaquín Sorolla de 1881 à 2009 / The reception of Sorolla's complete works, from 1881 to 2009

Fauvey, 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.
79

Experimental investigation of film cooling effectiveness on gas turbine blades

Gao, 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.
80

Experimental investigation of film cooling effectiveness on gas turbine blades

Gao, 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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