Dissertations / Theses on the topic 'BLADE ANGLES'
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Weiss, Samuel Bruce. "Vertical axis wind turbine with continuous blade angle adjustment." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/65178.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student submitted PDF version of thesis.
Includes bibliographical references (p. 26).
The author presents a concept for a vertical axis wind turbine that utilizes each blade's entire rotational cycle for power generation. Each blade has its own vertical axis of rotation and is constrained to rotate at the rate of one half of a revolution per full revolution of the rotor. For a rotor of radius r and blades of width b, a technical analysis predicts a theoretical maximum power coefficient of CP = b 2r+b, neglecting wind flow interference by upwind blades. This theoretical power coefficient is generally greater than the efficiency of a typical Savonius wind turbine (CP ~~ 0.15), and it reaches CP = 0.5 at the limiting blade width, b = 2r. The analysis also predicts a static torque and optimal tip-speed ratio that are both greater than those of a Savonius wind turbine with similar blade dimensions. Design considerations for implementing the kinematic constraint and for blade adjustment to account for changes in wind direction are discussed, and the author's prototype is presented. Testing of the prototype demonstrated that implementation of the kinematic constraint is feasible, and that efficiencies greater than those achievable by a Savonius turbine are plausible. In 4 m s wind conditions, the prototype yielded an estimated CP of 0.15, with much room for improvement through design changes and blade optimization in future iterations of this style of turbine.
by Samuel Bruce Weiss.
S.B.
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Carrasco, Mora Enrique. "Variable Stator Nozzle Angle Control in a Turbocharger Inlet." Thesis, KTH, Kraft- och värmeteknologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-174345.
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Turbochargers are becoming an essential device in internal combustion engines as they boost the intake air with more pressure in order to increase the power output. These devices are normally designed for a single steady design point but the pulsating flow delivered from the internal combustion engine is everything but steady. The efficiency drop experienced in the off-design points by the fixed geometry turbochargers have made some research groups to look into new variable geometry solutions for turbocharging. A nozzle ring is a device which normally achieves a higher performance under design conditions, but the efficiency rapidly drops at off-design conditions. In this paper, a variable angle nozzle ring is designed and implemented in the model of a radial turbine of a turbocharger in order to study its potential when working under real internal combustion engine cycles. To understand the profit margin the turbine performance is compared with two turbines with the same impeller geometry: one without nozzle ring and one with a nozzle ring with a fixed angle. The results show that the maximum efficiency angle function calculated for the variable angle nozzle ring achieves an improvement in the total efficiency of 5 % when comparing with a turbine with a fixed angle and 18 % when comparing with a vaneless turbine. The improved guidance achieved due to the variable blade angle leads to less turbine losses and therefore more mechanical energy can be extracted from the exhaust mass flow throughout all the combustion cycle but a further study should be made in order to match all the engine operations points. Notably, taking the pulsating boundary conditions into consideration, a remarkable improvement is achieved already for the fixed angle nozzle ring.
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Harson, Andrew. "A blade angle control system for large variable pitch fans." Thesis, Queen's University Belfast, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334529.
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Austin, Jeffrey G. "Mach number, flow angle, and loss measurements downstream of a transonic fan-blade cascade." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA280907.
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Riyad, Iftekhar A. "An Analysis of Harmonic Airloads Acting on Helicopter Rotor Blades." ScholarWorks@UNO, 2018. https://scholarworks.uno.edu/td/2507.
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Rotary wing aircrafts in any flight conditions suffer from excessive vibration which makes the passengers feel uncomfortable and causes fatigue failure in the structure. The main sources of vibration are the rotor harmonic airloads which originate primarily from the rapid variation of flow around the blade due to the vortex wake. In this thesis, a mathematical model is developed for rotor blades to compute the harmonic airloads at rotor blades for two flight conditions vertical takeoff and landing, and forward flight. The sectional lift, drag, and pitching moment are computed at a radial blade station for both flight conditions. The lift at a particular radial station is computed considering trailing and shed vortices and summing over each blade. The results for airloads are obtained after considering zeroth, first, and second harmonics. The calculated results for airloads are compared to the experimental flight-test data.
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Sundberg, Johanna, Martina Lundberg, Julia Solhed, and Aikaterini Manousidou. "Two-dimensional Study of Blade Profiles for a Savonius Wind Turbine." Thesis, Uppsala universitet, Elektricitetslära, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-412795.
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A Savonius wind turbine is a self-starting vertical axis rotor. It can be designed to be compact in size and also produces less noise which makes it suitable to integrate into urban spaces such as rooftops and sign-poles. These characteristics make it interesting from a sustainability point of view, especially when aiming to increase the decentralization of electricity production. This thesis aimed to investigate the aerodynamic performance of different two-bladed Savonius profiles by varying the blade arc angle and the overlap ratio. For evaluation, the dimensionless power coefficient and torque coefficient were investigated over different tip speed ratios. The study was conducted numerically with 2D simulations in Ansys Fluent. The partial differential equations describing the characteristics of the flow, including the flow turbulence effects, were solved with the Reynolds-average Navier Stokes in combination with the k-omega SST model. A validation was performed by comparing data from simulated and experimental tests of a semi-circular profile and a Benesh profile. The investigation of the blade arc angle and overlap ratio was performed on a Modified Bach profile. The profile with a blade arc angle of 130 degrees and an overlap ratio of 0.56 generated a maximal power coefficient of 0.267 at a tip speed ratio of 0.9. This blade configuration generated the best performance of all conducted simulations in this project. However, this project contained uncertainties since simulations can never be an exact description of reality. The project was also limited by the computational power available. Nevertheless, according to the conducted simulations, it was observed that a higher blade arc angle and a larger overlap ratio seem to generate higher efficiency.En Savonius vindturbin är en självstartande vertikalaxlad rotor som kan utformas i en kompakt design samtidigt som den producerar mindre oljud än horisontalaxlade vindkraftverk. Dagens hållbarhetssträvan i kombination med Savonius turbinens karakteristiska egenskaper gör den till ett potentiellt starkt vertyg för vindenergi. Då den kan placeras på exempelvis hustak eller skyltstolpar, utan att störa närliggande omgivning, finns det många möjliga sätt att implementera och integrera den i samhällets infrastruktur. Målet med detta projekt var att undersöka den aerodynamiska prestationen för Savoniusturbiner med två blad genom att variera bladvinkeln och överlappningsförhållandet. För att jämföra de olika profilerna användes den dimensionslösa effektkoefficienten och momentkoefficienten. Dessa koefficienter beräknades i förhållande till löptalet. Studien utfördes numeriskt med 2D-simuleringar i Ansys Fluent. De partiella differentialekvationerna som beskriver flödets egenskaper, inkluderat turbulenseffekterna, löstes med Reynolds-average Navier Stokes i kombination med k-ω SST modellen. En validering utfördes genom att jämföra data med simulerade och experimentella värden av en Semi-circular profil och en Benesh profil. Studien av bladvinkel och överlappningsförhållandet utgick från en Modified Bach profil. Den mest effektiva profilen hade en bladvinkel av 130 grader och ett överlappsförhållande på 0,56. Den genererade en maximal effektkoefficient av 0,267 vid löptal 0,9. Projektet innehöll en del osäkerheter då simuleringar aldrig kan beskriva verkligheten till fullo. Den tillgängliga beräkningskapaciteten begränsade även projektet ytterligare. Trots vissa begränsningar, visar ändå utförda simuleringar att ökad bladvinkel och ökat överlappningsförhållande genererar högre effekt.
This project was conducted within Stand up for wind and Stand up for energy.
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Russ, Thomas William. "A surface flow visualization study of boundary layer behavior on the blades of a solid-wall compressor cascade at high angles of attack." Thesis, Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/53161.
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The oil-film surface flow visualization technique was applied to circular arc compressor blades in a solid wall, high aspect ratio cascade for the purpose of describing the transition from corner stall to full blade stall, and the blade surface flow under fully stalled conditions. Photos of the visualizations for three stagger angles are presented and analyzed. A map quantitatively describing the observed boundary layer development at midspan is presented.
The most interesting discovery of the work showed the suction surface flow to be essentially two-dimensional, in the geometric sense, preceding and following the transition to a fully separated flow at the leading edge. Corner stall was the observed three-dimensional mechanism prior to full stall. For fully-stalled conditions, the three-dimensional mechanism took the form of recirculating flow regions at the blade ends. Complete separation at the leading edge occurred at lower angles of attack for the higher stagger angles. Special blade oil-flow tests were conducted to evaluate Reynolds number and tip clearance effects on boundary layer development.
The experimental work was done as part of a larger research program aimed at measuring and predicting the stalled performance of a compressor cascade.Master of Science
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Lewis, Daniel Russell. "Tip clearance and angle of attack effects upon the unsteady response of a vibrating flat plate in crossflow." Thesis, Virginia Tech, 1993. http://hdl.handle.net/10919/43198.
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The influence of tip clearance and angle of attack upon the mid-span unsteady pressure response of a vibrating flat plate was investigated experimentally. Unsteady pressure measurements were taken for a variety of incidence angles, vibration frequencies and tip clearances over a Mach number range of 0.2 to 0.6.
It was found that changes in tip clearance had an effect on measured pressure fluctuations at higher angles of attack and larger Mach numbers. It was also observed that the amplitude of the unsteady pressure increased as the incidence angle was increased.
The plate was mechanically induced to oscillate in translation, simulating the flISt bending mode. Averaged Fast Fourier Transforms were used to determine pressure oscillation amplitudes and phase lags with respect to the plate motion.
Master of Science
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Герасимчук, Галина Андріївна, and Galina Gerasimchuk. "Обґрунтування параметрів комбінованого однодискового копача кормових буряків." Thesis, Тернопільський національний технічний університет ім. Івана Пулюя, 2011. http://elartu.tntu.edu.ua/handle/123456789/877.
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Робота виконана у Луцькому національному технічному університеті Міністерства освіти і науки, молоді та спорту України, м. Луцьк.
Захист відбувся 3 березня 2011 р. о 1200 годині на засіданні спеціалізованої вченої ради Д.58.052.02 при Тернопільському національному технічному університеті імені Івана Пулюя за адресою: 46001, м. Тернопіль, вул. Руська, 56.
З дисертацією можна ознайомитись в бібліотеці Тернопільського національного технічного університету імені Івана Пулюя за адресою: 46001, м. Тернопіль, вул. Руська, 56.Дисертація присвячена вирішенню наукової задачі підвищення показників якості збирання кормових буряків шляхом обґрунтування параметрів комбінованого копача, виконаного у вигляді сферичного диска, встановленого під кутом атаки до напрямку його руху, у робочій зоні якого і над ним змонтовано горизонтальний вал з очисними лопатями, які закріплено на осях, повернутих відносно осі вала на деякий кут. На основі проведених теоретичних і експериментальних досліджень обґрунтовано раціональні параметри копача. Результати досліджень використовуються проектно-конструкторськими організаціями в процесі розробки КМ.
В диссертации на основании совокупности обобщенных результатов решена актуальная научная задача, которая состоит в повышении показателей качества работы выкапывающих рабочих органов кормовой свеклы путем обоснования параметров работы комбинированного однодискового копателя. В первом разделе проведен анализ литературных источников. В частности, рассмотрены классификация выкапывающих рабочих органов и очистителей головок корнеплодов кормовой свеклы, их конструкции, основные технологии сбора кормовой свеклы, а также обоснован выбор рабочего органа для проведения исследований. Во втором разделе теоретически исследовано секундные подачи примесей вороха корнеплодов и коэффициенты технологической эффективности работы копателя в зависимости от параметров копателя, характеристик корнеплодов и условий работы корнеуборочной машины. На основании анализа процесса взаимодействия очистительной лопати горизонтального вала с головкой корнеплодов получены математические модели, характеризирующие условия невываливания корнеплодов с почвы та их неповреждения, определена критическая угловая скорость вращения лопати. В третьем разделе представлено программу экспериментальных исследований, приведено перечень оборудования, приборов, разработанных опытных установок и методики проведения исследований. С учетом программы экспериментальных исследований изготовлена экспериментальная лабораторно-полевая установка комбинированного копателя кормовых корнеплодов. В четвертом разделе приведены результаты экспериментальных исследований. Установлено влияние конструктивно-кинематических параметров копателя на секундные подачи примесей вороха и основные показатели качества работы – потери, повреждения корнеплодов, остатки ботвы на головках корнеплодов. В пятом разделе определены перспективные направления усовершенствования конструкций рабочих органов копателей и основные показатели экономической эффективности использования копателя. Конструктивная новизна разработок защищена двумя патентами Украины на изобретения.
Dissertation is devoted to the scientific problem of improving indexes of quality of gathering fodder beet by grounding parameters of combined digger, designed as a spherical disc which is set due to an angle of attack to the direction of its movement in the working area of which it is mounted a horizontal shaft with scrubbing blades that are fixed on turned on defined angle axis according to axis of a shaft. It was grounded rational parameters of a digger on the basis of theoretical and experimental studies. Research results are used by design organizations in the development of RDM.
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Bouchet, Claire. "Les métaphores dans la poésie de William Blake : enjeux de traduction." Paris 3, 2004. http://www.theses.fr/2004PA030125.
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Cette étude a pour objet de montrer, mesurer et qualifier l’apport d’une approche traductive à l’herméneutique littéraire. Le champ d’étude est circonscrit à la figure particulière de la métaphore, au sein de cette partie de l’œuvre poétique de William Blake que l’on appelle les Livres Prophétiques, et à travers quatre de leurs traductions. Le repérage des références extra-textuelles, le décodage des réseaux intratextuels, l’analyse des choix de traduction selon les contraintes de la sémantique, de la syntaxe ou de la morphologie, tant de la langue de départ que de la langue d’arrivée et l’analyse des spécificités de l’écriture poétique contribuent à montrer que la traduction est une activité créatrice qui se fonde sur un travail de lecture spécifique et qui fait du traducteur un critique littéraire, un révélateur du style de l’auteur et un créateur d’œuvre littéraireThis study aims at probing, measuring and defining how the act of translating can contribute to literary analysis. It concentrates particularly on metaphors as they appear in four French translations of William Blake’s “Lambeth Books”. Translation is an activity which involves defining the cultural references of the work of art as well as the inner networks of imagery, and leads to making decisions in translating the text, according to the rules of semantics, syntax or morphology in both languages. Added to the analysis of the specificity of poetry writing, all these elements tend to show that translating is a creative activity based on a specific strategy of reading and which show how the translator is also a literary critic, the initiator into an author’s style and a creator of literary works
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Wang, Qiang. "The Dynamics of Workplace Harassment and Revenge: Mediation and Moderation Effects." Wright State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=wright1221586560.
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Fernström, Vilma. "Böjning av kräppschabern vid mjukpapperstillverkning : Ändring av kräppvinkeln." Thesis, Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-74460.
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Inom mjukpappersindustrin är det viktigt att utvecklas och upprätthålla en så bra kvalité som möjligt på produkterna för att hålla sig kvar på marknaden. Det är därför betydelsefullt att ha kunskap kring tillverkningsprocessens alla steg och hur de påverkar det slutgiltiga resultatet. En viktig del av tillverkningen är kräppningsprocessen som till stor del ger papperet sina egenskaper och kvalité. Det är i detta steg av tillverkningen som strukturen på papperet bestäms. Detta gör att ett stort fokus ligger på att förstå och utveckla kräppningsprocessen. Denna rapport görs i samarbete med en mjukpapperstillverkare som under den senaste tiden upptäckt en större efterfrågan hos kunder att vara med och styra inställningarna av kräppschabern. Då det råder en bristande kunskap om hur olika faktorer påverkar kräppningen har en osäkerhet uppstått. Syftet med denna rapport är att bidra med den kunskap som krävs kring kräppningsprocessen och klingegenskaperna för att företaget ska ha möjlighet att tillfredsställa kundernas efterfrågan och behov. I kräppningsprocessen är kräppschabern den viktigaste komponenten att granska då det är denna klinga som utför själva kräppningen. De mest relevanta faktorerna för kräppschaberns inställning väljs ut för att undersökas i denna rapport. Analysen av parametrarna utförs genom att variera en parameter i taget för att sedan kontrollera hur böjningen av kräppschabern ser ut. Med hjälp av utböjningen av klingan kan sedan en kräppvinkel beräknas för att slutligen få fram förhållandet mellan de utvalda parametrarna och kräppvinklen. Detta kommer utföras med hjälp av tre olika metoder vars resultat sedan jämförs med varandra för att fastställa de beräknade förhållandena. De olika metoderna som används är en analytisk beräkning som baseras på den elastiska linjens ekvation samt två undersökningar i FEM-program där klinggeometrin modelleras. Plottar utformas med värden från de olika undersökningarna som grund. Ett diagram för varje parameter skapas, diagrammen visar hur kräppvinkeln ändras då parametern varierar inom de utvalda intervallen. Alla parametrar som undersökts visade sig påverka kräppvinkeln på en nivå som gör de relevanta för inställningen av kräppschabern då en önskad kvalité är efterfrågad. Efter en jämförelse mellan resultaten från de olika metoderna kunde vissa avvikelser hittas. Dessa avvikelser är dock inte stora och kan därför försummas. Det finns många tänkbara anledningar till avvikelserna som t.ex. olika antaganden och beräkningsmässiga skillnader. Slutsatserna som kan göras av denna rapport är att alla de parametrar som undersöktes har en betydande roll för kräppvinklens minskning och att de olika beräkningssätten gav överensstämmande resultat. I framtida undersökningar kan därför den smidigaste av de undersökta metoderna rekommenderas.In the tissue industry, it is important to develop and maintain as good a quality as possible on the products in order to stay on the market. It is therefore important to have knowledge of all the steps of the manufacturing process and how they affect the final result. An important part of the production is the creping process, which largely gives the paper its properties and quality. It is in this stage of manufacturing process that the structure of the paper is determined. This means that a great focus is to understand and develop the creping process. This report is made in collaboration with a tissue manufacturer who recently discovered a greater demand from customers to participate in and control the settings in their projects. Since there is a lack of knowledge of how different factors affect the creping, uncertainty has arisen. The purpose of this report is to contribute with the knowledge required about the creping process in order to reduce uncertainty in the company and satisfy the customers' demand and needs. In the creping process, creping blade is the most important component to examine as it is this blade that performs the creping itself. The most relevant factors for the creping blades settings are selected to be examined in this report. The analysis of the parameters is performed by varying one parameter at a time and then checking how the bending of the creping blade looks. With the deflection of the blade, a crepe angle can be calculated in order to highlight the relationship between the chosen parameters and the crepe angle. This will be accomplished by using three different methods, the results of which are then compared with each other to determine the calculated conditions. The different methods who are used is an analytical calculation based on the linear elasticity equation and two studies in FEM programs where the blade geometry is modeled. Plots are designed, displaying values from the different analysis’s as a basis. A chart for each parameter is created, the charts show how the crepe angle changes as the parameter varies within the selected intervals. All parameters examined were found to affect the crepe angle more or less, but all at a level that makes them relevant to the setting of the creping blade as a certain desired quality is required. After a comparison of the results from the different methods, some deviations could be found. However, these deviations are not significant and may therefore be ignored. There are many possible reasons for these deviations such as e.g. various presumptions and computational differences. The conclusions that can be made about this report are that all the parameters that were examined have a significant role in the reduction of the crepe angle and that the results from the various methods gave consistent results. In future investigations, therefore, the most convenient of the methods tested may be recommended.
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Puentes, Katerina. "On the effects of preservation , blade angle and intra- and inter-individual differences on the identification of tool class characteristics retained on human costal cartilage in cut marks analysis." Master's thesis, Faculdade de Medicina da Universidade do Porto, 2011. http://hdl.handle.net/10216/63789.
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Puentes, Katerina. "On the effects of preservation , blade angle and intra- and inter-individual differences on the identification of tool class characteristics retained on human costal cartilage in cut marks analysis." Dissertação, Faculdade de Medicina da Universidade do Porto, 2011. http://hdl.handle.net/10216/63789.
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Maher, Sean William. "Noir and the urban imaginary." Thesis, Queensland University of Technology, 2010. https://eprints.qut.edu.au/42216/1/Sean_Maher_Thesis.pdf.
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Noir and the Urban Imaginary is creative practice based PhD research comprising critical analysis (40%) exegesis (10%) and a twenty-six minute film, The Brisbane Line (50%). The research investigates intersection of four elements; the city, the cinema, history and postmodernity. The thesis discusses relationships between each of the four elements and what cinematic representation of cities reveals about modern and postmodern urban experience and historicisation. Key concepts in the research include, 'urbanism', 'historiography', 'modernity', 'postmodernity', 'neo-noir'.
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Macháček, Tomáš. "Návrh stabilizátoru automobilu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230471.
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Tato diplomová práce je zaměřená na stabilizátory u podvozku aut. První část popisuje všeobecné znalosti vlivu naklonění karosérie na jizdní vlastnosti auta a možnosti konstrukčních řešení používaných v praxi. Dále jsou v této části uvedeny nevýhody použití stabilizátoru a jejich náhrady. Nasledující téma se zaměřuje na soutěž Formule Student a její všeobecná pravidla. Hlavní částí této práce je analýza stabilizátoru Formule Ford, na kterou v poslední části této práce navazuje analýza předního a zadního stabilizátoru Formule Student. Byly vytvořené kompletní MBS modely pro přední a zadní zavěšení včetně stabilizátoru. Díky těmto modelům bylo možné provést výpočty klopných tuhostí a pevnostní výpočty. Z těchto výpočtů bylo možné určit vhodné nastavení stabilizátoru. Všechny modely mohou být dále použitelné pro analýzu jízdních vlastností příslušného vozidla.
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Мілтих, Вікторія Станіславівна, Виктория Станиславовна Милтых, and Viktoriia Stanislavivna Miltykh. "Підвищення енергоефективності насосної станції з насосами типу д впливом геометричних параметрів їх робочих коліс на форму напірної характеристики." Thesis, Сумський державний університет, 2016. http://essuir.sumdu.edu.ua/handle/123456789/46028.
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Робота спрямована на подальший розвиток науково-методичного забезпечення розв’язання задачі підвищення енергетичної ефективності роботи насосної станції з насосами типу Д шляхом заміни їх робочих коліс на нові, спроектовані з наперед визначеною крутизною напірної характеристики. За результатами огляду науково-технічної інформації визначена та обґрунтована актуальність теми дисертаційної роботи, сформульовані її мета і задачі. Поставлену наукову задачу вирішено шляхом впливу на крутизну напірної характеристики насоса зміною ширини робочого колеса на виході.
За результатами математичного моделювання робочого процесу робочих коліс насосів типу Д отримано картини течії у робочому колесі та визначено вплив зміни його ширини на виході на його напірні та енергетичні характеристики. Математична залежність крутизни напірної характеристики від ширини робочого колеса на виході отримана за умови незмінності інших геометричних розмірів елементів проточної частини насосів типу Д. На базі результатів проведеного дослідження уточнено математичну модель функціонування насосної станції з насосами типу Д при використанні ступеневого регулювання її подачі, яка комплексно враховує характеристику гідравлічної мережі, форму напірної характеристики насоса та спосіб регулювання подачі насосної станції. Існуюча методика розрахунку робочого колеса доповнена залежністю крутизни напірної характеристики від ширини робочого колеса на виході для проектування з наперед визначеною крутизною напірної характеристики, що дає можливість підвищення енергоефективності функціонування насосних агрегатів типу Д у складі насосних станцій.Работа направлена на дальнейшее развитие научно-методического обеспечения решения задачи повышения энергетической эффективности работы насосной станции с насосами типа Д путем замены их рабочих колес на новые, спроектированные с предопределенной крутизной напорной характеристики. По результатам анализа научно-технической информации определена и обоснована актуальность темы диссертационной работы, сформулированы ее цели и задачи. Поставленную научную задачу решено путем воздействия на крутизну напорной характеристики насоса изменением ширины рабочего колеса на выходе. По результатам математического моделирования с использованием численных моделей получено картины течения в рабочем колесе и определено влияние изменения его ширины на выходе на его напорные и энергетические характеристики. Математическая зависимость крутизны напорной характеристики от ширины рабочего колеса на выходе получена при неизменности других геометрических размеров элементов проточной части насосов типа Д. Для колес насосов типа Д с ns = 85...160 впервые определен диапазон изменения крутизны напорной характеристики, которая достигается изменением ширины рабочего колеса на выходе, при отклонении показателей энергоэффективности функционирования насоса в пределах 5 % от их номинальных значений. Установлено, что с уменьшением относительной ширины b2/D2 исследуемых рабочих колес, функция характеристики мощности уменьшает скорость возрастания, а при некотором ее значении мощность начинает уменьшаться в диапазоне подач больших за расчетное значение На базе результатов проведенного исследования уточнено математическую модель функционирования насосной станции с насосами типа Д при использовании ступенчатого регулирования ее подачи, которая комплексно учитывает характеристику гидравлической сети, форму напорной характеристики насоса и способ регулирования подачи насосной станции. Существующая методика расчета рабочего колеса дополнена зависимостью крутизны напорной характеристики от ширины рабочего колеса на выходе для проектирования с предопределенной крутизной напорной характеристики, что предоставляет возможность повысить энергоэффективность функционирования насосных агрегатов типа Д в составе насосных станций.
The work is focused on the further scientific and methodological support development of the improving the energy efficiency of the pumping station with pumps of type D problem solving by replacing its impellers on the new ones, which are designed with predetermined slope of characteristic curve. According to the scientific and technical information analysis results, the dissertation theme relevance is determined and grounded, its goals and objectives are formulated. The assigned scientific task is solved by affecting on slope of characteristic curve changing impeller outlet width. According to the mathematical modeling results using numerical models, impeller flow patterns are developed and its width output changing effect on its pressure and power characteristics is determined. Slope of characteristic curve mathematical dependence on impeller outlet width is obtained using other type D pumps firm parts elements geometrical dimensions. For type D impellers with ns = 85...160 the slope of characteristic curve change range was firstly defined, which is achieved by impeller outlet width changing under pump operation energy efficiency rate deviation within 5 % from its nominal values. On the basis of the study results, the pumping station with type D pumps functioning mathematical model was refined, using its step control supply, which takes into account hydraulic network characteristics, characteristic curve form and the pump station supply regulating method. The existing impeller calculating method is complemented by slope of characteristic curve from impeller output width for engineering with predetermined slope of characteristic curve, which provides an opportunity to increase energy efficiency of type D pumping units functioning being a part of the pumping stations.
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Липовий, Віталій Миколайович, Виталий Николаевич Липовый, and Vitalii Mykolaiovych Lypovyi. "Підвищення енергетичних показників ортогональних вітродвигунів для використання вітрових потоків малої потужності." Thesis, Вид-во СумДУ, 2015. http://essuir.sumdu.edu.ua/handle/123456789/40886.
Full textAbstract:
Дисертація на здобуття наукового ступеня кандидата технічних наук за
фахом 05.05.17 – гідравлічні машини та гідропневмоагрегати. – Сумський
державний університет, Суми, 201 5.
У дисертаційній роботі приведено вирішення питання самозапуску
вертикально-осьового вітродвигуна для малих та середніх розмірів вітроколіс
при використанні вітрових потоків низької потужності. Розроблено
аналітичний метод визначення оптимальних характеристик потоку повітря для
продукування максимального тягового зусилля на всій траєкторії руху лопаті.
Чисельним моделюванням обтікання лопаті потоком повітря вирішено питання
визначення аеродинамічних коефіцієнтів для заданого профілю, що з певним
припущенням дозволяє відмовитися від натурного експерименту продувки
профілю в аеродинамічній трубі.
Запропоновано механізм впливу на ортогональне вітроколесо шляхом
уведення допоміжного вектору швидкості, з метою підвищення його
аеродинамічних характеристик. Цей механізм випробувано на
експериментальному стенді та доведено доцільність його використання під час
роботи вітроколеса на нерозрахункових режимах.
У результаті досліджень визначено показники крутних моментів на валу
ортогональної вітротурбіни з прямими лопатями парусного типу. Доведено
підвищення стартового тягового моменту. Для запропонованих конструкцій
симетричних гнучких профільованих лопатей наведені інтегральні
характеристики при змінних геометричних показниках вітроколеса.
Результати дисертаційної роботи дозволяють розробляти високоефективні
вітроенергетичні установки, орієнтовані на використання вітрових потоків
низької потужності, що є актуальним для території України.Диссертация на соискание ученой степени кандидата технических наук по специальности 05.05.17 - гидравлические машины и гидропневмоагрегаты. - Сумской государственный университет, Сумы, 2015. В диссертационной работе приведены решения вопроса самозапуска вертикально-осевого ветродвигателя для малых и средних размеров ветроколес при использовании ветровых потоков низких мощностей. Разработан аналитический метод определения оптимальных характеристик потока воздуха для возникновения максимального тягового усилия на всей траектории движения лопасти. Численным моделированием обтекания лопасти потоком воздуха решен вопрос определения аэродинамических коэффициентов для заданного профиля, что с определенным предположением позволяет отказаться от натурного эксперимента продувки профиля в аэродинамической трубе. Предложен механизм влияния на ортогональное ветроколесо путем введения вспомогательного вектора скорости с целью повышения его энергетических характеристик. Данный механизм испытано на экспериментальном стенде и доказана целесообразность его использования при работе ветроколеса на нерасчетных режимах. Впервые разработано двухструйную математическую модель ортогонального ветродвигателя для определения кинематических характеристик потока воздуха, которые влияют на повышение мощности ветроколеса. Разработано аналитические зависимости для определения влияния на эффективность работы ветротурбины дополнительного вектора скорости W̅', что приводит к смещению треугольников скоростей в сторону увеличения тяговой силы на поверхности лопасти. В результате исследований определены показатели крутящих моментов на валу ортогональной ветротурбины с прямыми лопастями парусного типа. Доказано повышение стартового тягового момента. Для предложенных конструкций симметричных гибких профилированных лопастей приведены интегральные характеристики при переменных геометрических показателях ветроколеса. Экспериментальным путем определено, что введение вспомогательного вектора скорости путем установки экрана на дуге круговой траектории в области нулевого азимутального угла β=0 позволяет повысить мощность ветроколеса. Плоский экран длинной 120 мм, наклоненный под углом 20° на азимутальном угле 36° повышает генерируемую мощность ветроколеса в 2,5 раза. Определено, что использование гибких парусных лопастей симметричного профиля позволяет получить высокие значения начального крутящего момента на валу ортогональной ветротурбины. При низкой быстроходности θ ˂ 0,5 значение коэффициента крутящего момента составляет Cm = 0,47. При дальнейшем разгоне ветроколеса Cm падает до значения жесткой симметричной лопасти C m = 0,1. Результаты диссертационной работы позволяют разрабатывать высокоэффективные ветроэнергетические установки, ориентированные на использование ветровых потоков низкой мощности, что актуально для территории Украины.
Thesis for the degree of candidate of technical sciences, specialty 05.05.17 - hydraulic machines and hydropneumaticunits. – Sumy State University, Sumy, 2015. The thesis shows the solution to the question of self-start of vertical-axis wind turbine for small and medium-sized windwheels using wind currents low capacity. An analytical method for determining the optimal characteristics of the air flow for the occurrence of maximum power to the entire trajectory of the blade. Numerical simulation of flow around the blade airflow resolved the question of determining the aerodynamic coefficients for a given profile, with certain assumptions eliminates the natural experiment blowing in the wind tunnel profile. The mechanism of the effect of the orthogonal wind wheel, by introducing auxiliary velocity vector, in order to improve its energy performance. This mechanism is tested on experimental stand and prove the feasibility of its use in the operation of the wind wheel on the off-nominal conditions. The studies identify indicators torque of the orthogonal wind turbine with straight blades sailing type. Proven to increase the starting of torque. For the proposed construction of symmetric flexible profiled blades are given integral characteristics with variable geometry have been the propeller. The results of the thesis allow you to develop highly efficient wind turbines focused on the use of wind flows low power, which is important for Ukraine.
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Цьонь, Олег Петрович, and O. P. Tsion. "Удосконалення конструкції дообрізувача гички цукрових буряків активного типу." Thesis, Тернопільський національний технічний університет ім. Івана Пулюя, 2014. http://elartu.tntu.edu.ua/handle/123456789/5432.
Full textAbstract:
Робота виконана у Тернопільському національному технічному університеті імені Івана
Пулюя Міністерства освіти і науки України.
Захист відбувся “ 27 ” січня 2015 року о “ 14 ” годині на засіданні спеціалізованої
вченої ради Д 58.052.02 в Тернопільському національному технічному університеті імені Івана
Пулюя за адресою: 46001, м. Тернопіль, вул. Руська, 56, аудиторія 79.Удосконалення конструктивної схеми доочисника головок коренеплодів, який забезпечує підвищення показників надійності та якості виконання технологічного процесу, можливо досягти шляхом розроблення гичкозрізуючого пристрою з активним плоским ножем. Перевагою запропонованого конструктивного рішення, порівняно з активним дисковим ножем, є підвищена експлуатаційна надійність, значно менша маса та простота виготовлення.
Дисертацію присвячено питанням підвищення ефективності та надійності технологічного процесу дообрізування залишків гички з головок коренеплодів цукрових буряків на основі обґрунтування конструктивно-технологічних параметрів механізму дообрізувача гички активного типу. Теоретично досліджено: процес взаємодії активного плоского ножа з головками коренеплодів при режимі різання з ковзанням; НДС ножа при приведенні у рух; модель руху дообрізувача гички з активним робочим органом по рядках коренеплодів цукрових буряків; коефіцієнт ковзання в системі “коренеплід – плоский ніж”. Експериментально досліджено залежність сили різання головок цукрових буряків активним плоским ножем від робочої швидкості бурякозбирального агрегату; зворотно-поступальної швидкості ножа та товщини його леза; діаметра коренеплодів. Встановлено корозійний вплив на функціональну здатність конструкційних матеріалів ножів середовища соку цукрових буряків. Застосування запропонованої конструкції дообрізувача активного типу дозволить підвищити ефективність та надійність процесу доочищення головок коренеплодів цукрових буряків від залишків гички.
The thesis is dedicated to the problem of improving the efficiency and reliability of technological topping the residual tops of sugar beet crowns taking into consideration the structural and technological parameters of an active type topper. The following aspects are theoretically researched: interaction of an active flat knife with the root beet crowns in mode of cutting with sliding; tensely deformed status of that knife when moving; model of moving the topper with active working bodies along sugar root beets rows; coefficient of sliding in the system “root – flat knife”. The dependence of sugar beet crowns cutting force by means of active flat knife on the working speed of a beet harvester, as well as on the knife reciprocating speed, knife blade thickness, root diameter, is developed experimentally. The corrosion effect of beet juice on functional capability of knife structural materials is researched. The use of active type topper design will improve the efficiency and reliability of toping the sugar beet crowns.
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Desenfans, Philip. "Aerodynamics of the Maple Seed." Aircraft Design and Systems Group (AERO), Department of Automotive and Aeronautical Engineering, Hamburg University of Applied Sciences, 2019. http://d-nb.info/1204982848.
Full textAbstract:
Purpose - The paper presents a theoretical framework that describes the aerodynamics of a falling maple (Acer pseudoplatanus) seed. --- Methodology - A semi-empirical method is developed that provides a ratio stating how much longer a seed falls in air compared to freefall. The generated lift is calculated by evaluating the integral of two-dimensional airfoil elements using a preliminary falling speed. This allows for the calculation of the definitive falling speed using Blade Element Momentum Theory (BEMT); hereafter, the fall duration in air and in freefall are obtained. Furthermore, the input-variables of the calculation of lift are transformed to require only the length and width of the maple seed. Lastly, the method is applied to two calculation examples as a means of validation. --- Findings - The two example calculations gave percentual errors of 5.5% and 3.7% for the falling speed when compared to measured values. The averaged result is that a maple seed falls 9.9 times longer in air when released from 20 m; however, this result is highly dependent on geometrical parameters which can be accounted for using the constructed method. --- Research limitations - Firstly, the coefficient of lift is unknown for the shape of a maple seed. Secondly, the approximated transient state is yet to be verified by measurement. --- Originality / Value - The added value of this report lies in the reduction of simplifications compared to BEMT approaches. In this way a large amount of accuracy is achieved due to the inclusion of many geometrical parameters, even though simplicity is maintained. This has been accomplished through constructing a simple three-step method that is fundamental and essentially non-iterative.
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Chang, Chih-Lin, and 張志凌. "The effects of proper tactics and blade angles on fencing performance." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/68040987541899142688.
Full textAbstract:
碩士國立臺灣體育學院
體育研究所
89
ABSTRACT The purpose of this study aim to adjust the direction of training through the study of tactics, from the view of human factors to evaluate the influence on efficiency and injury, through different tactics and blade angles. Skill and good physical training are the very fundamental elements to execute tactics properly. In research of tactics with the ANOVA and Duncan’s Grouping Multiple tests, fencers in 1999 World Championship clearly reflect that different attacks - tactics determined the result of a fight. Dividing these fencers into two groups (group of winner and group of loser), we could see the frequency of using attack to achieve a winning hit in both groups were the same; but to those whom used more counter attack in competition, it definitely promoted them into the winners group. Attack should always be the essential tactic, but coaches should also realize that counter attack affect the result. The speed in a fight is accelerated by footworks, the most serious injuries among Taiwan fencers are ankle joint, as well as waist, knee and thigh. We could easily find these information from foreign documentation, and it should helps to avoid these injuries.Wrist injuries is the most common part on upper body. In the experiment of blade angles, the ANOVA Multiple tests indicated that different blade angles effect various accuracy with fling hit. Blade angle at 9 degree created highest accuracy in experiment, can also accelerate counter attack to highest performance. More downward the angle is, less ulnar deviation appeared on wrist, saved strength and less fatigue. Therefore, from view of human factors research and in consideration of safety and efficiency, blade angle at 9 degree was the best choice. Key Words: Foil, attack, riposte, simultaneous attack, counter attack, fling hit, accuracy, exercising efficiency, ulnar deviation, radial deviation
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Yu, Kuo-Chuan, and 余國全. "Numerical Study of Changing Blade-Outlet-Angles on the performance of a Small Backward-Inclined Centrifugal Pump." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/87996677059518199196.
Full textAbstract:
碩士國立臺灣科技大學
機械工程系
93
Abstract Pump is widely used to the fluid transportation in the industry. Recently, the small centrifugal pump has drawn increasing attention on its application in the design of artificial heart. There is a substantial need to realize the flow patterns and shear-stress distribution generated by the pump for a safe application on human body. Therefore, this work aims at the application of the numerical code to simulate the associated flow field inside a small BI centrifugal pump. The numerical outcomes are utilized for the flow visualization to identify the possibility of performance enhancement. The designs of impeller and spiral housing adopted the design scheme that was recommended in the previous literatures. Consequently, a water pump comprised a 72.6-mm-diameter scroll housing and an impeller with 50-mm-diameter and seven airfoil blades is designed to meet the 5 l/min volume-flow-rate requirement for the artificial heart. Then, the efficiencies of pump with different blade outlet angles are analyzed numerically. The analysis shows that the max flowrate will be 4.08 l/min when the blade outlet angle is set at 30 . For the case of 22.5 blade outlet angle, the pressure around the rotor distributes uniformly and thus generates the tiniest vibrations on the pump. However, the results from the above analyses did not approach our previous design goal. Hence, this research intends to remove the rotor hub in order to enlarge the inlet area for producing extra mass flowrate. Numerical simulation indicates that the max flow rate increases about 69.5% while the pump’s output pressure enhances dramatically. In conclusion, this numerical result is not only matching the original design target but also proving that the inlet area affects the pump efficiency and performance substantially.
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KUMAR, MANISH. "SIMULATION OF FLOW AND HEAT TRANSFER IN A CHANNEL WITH RECTANGULAR VORTEX GENERATORS AT DIFFERENT REYONALD NUMBERS AND BLADE ANGLES." Thesis, 2015. http://dspace.dtu.ac.in:8080/jspui/handle/repository/15556.
Full textAbstract:
The compact heat exchanger is widely used in fields such as automobile industry, heating and air
conditioning, power system, chemical engineering, electronic chip cooling and aerospace, etc.
The subject of heat transfer enhancement is of significant interest in developing compact heat
exchanger to meet the desire of high efficiency and low cost with the volume as small as possible
and the weight as light as possible.
The use of ribs/baffles placing in the cooling channels or channel heat exchangers is one of the
commonly used passive heat transfer enhancement technique in single-phase internal flows.
Periodically positioned ribs/baffles in the channels interrupt hydrodynamic and thermal boundary
layers. Downstream of each rib/baffle the flow separates, recalculates, and impinges on the
channel wall and these effects are the main reasons for heat transfer enhancement in such
channels. The use of ribs/baffles increases not only the heat transfer rate but also substantial the
pressure loss. The rib/baffle geometry and arrangement in the channel also alter the flow field
resulting in different convective heat transfer distribution. In particular, the angled ribs, the rib
cross-section, the rib-to-channel height ratio and the rib pitch-to-height ratio are all parameters
that influence both the convective heat transfer coefficient and the overall thermal performance.
It is, thus, difficult to realize the advantage of rib/baffle arrangements or geometry and the use of
staggered ribs/ baffles with rib height and pitch spacing of 0.1 (0.5 for baffles) and 1 time of the
channel height respectively is often recommended in most of the previous work.
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HUNG, MING-CHUNG, and 洪銘泉. "Optimal Blade Angle Design forSmall Wind Turbines." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/89439503262929118395.
Full textAbstract:
碩士逢甲大學
航太與系統工程所
98
ABSTRACT The purpose of this thesis is to design a set of optimal blades for small wind turbines. For a three blade turbine, NACA airfoils and the twist angle of blades are studied to obtain the maximum power from the wind for blades with 1 m radius. Since lift coefficients correlate with surface roughness concern, we study the 4 digital NACA airfoil types, i.e., NACA 4408、4412、4415. This thesis is based on Workbench CFX computation in the condition of wind velocity 6 m/s to find out the optimal design for starting to work in the low wind velocity and obtaining the maximum torque in the field of middle Taiwan. After the evaluation of CFX data, as increase of airfoil thickness can capture more power of wind energy. Superior concern, NACA 4412 airfoil can be used for weight and power. Keyword : Blade of wind turbines, blade angle, wind turbine, NACA airfoil.
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Chen, Li-ru, and 陳麗如. "Effects of Blade Root Angle of Attack and Blade Twist on Fan Performance and Flow Characteristics." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/88011204003200186188.
Full textAbstract:
碩士國立臺灣科技大學
機械工程系
96
This study uses the STAR-CD, a commercial code of Computational Fluid Dynamics, to calculate and analyze the flow field characteristics and performance curve of an axial fan. The static grid is employed in the computation. A new computational approach other than the conventional simulation method, which is widely used by investigators, is developed. The flow field were obtained by changing the root angle, attack angle and blade torsion. Based on the data gathered from computer simulations, result show at least three emphases. First, the deviation of the calculated fan performance curve by using the new approach from the experimental results can attain a level less than 2%, which is a drastic improvement over that obtained by using the convention method. Second, during the separation, attach, vortex and recirculation flow at the surface of rotator blade, tip clearance and surface of stator blade will decay the fan’s performance. Such flow phenomenon dramatically decrease the worse performance of fan. Third, for the flow structure, changing the torsion angle will make the flow to become turbulent than changing the attack angle. Changing the fan’s attack angle guarantees better performance than changing the torsion angle.
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Tseng, Shih-Hou, and 曾世豪. "The Influences of Doctor Blade Angle on Gravure Printing Quality." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/44543875037990958556.
Full textAbstract:
碩士國立臺灣藝術大學
應用媒體藝術研究所
93
Gravure is one of the four major printing processes. Gravure printing products are full of our daily life. Most of the plastic packaging in the supermarket are printed by Gravure. Good printing quality is very important for printer to expand market. Most of the press operation items like tension control, dryer temperature, impression pressure, and registration have fixed data according to different substrates. The doctor blade angle adjustment is one of the two major controls in press run as well as ink viscosity. The doctor blade angle control plays a vital role in printing quality. In order to understand the influences of gravure doctor blade angle on printing quality, the research set different blade angle at 65, 60, 55, 45 degree to test on printing quality of solid ink density, tone value increase, printing contrast, trapping, color gamut, line resolution, and gradation. Each angle printed 100 pieces after test run and collected 35 pieces for mesurement by systematic random sampling. The data were recorded and analysed. The results of the study show that: 1.The doctor blade angle has significant influences on printing quality of solid ink density, tone value increase, line resolution, and gradation. 2.There is no influence on trapping and color gamut. 3.There is an influence on printing contrast, but it is minor
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LIN, CHENG-HONG, and 林承宏. "Effect and analysis of the blade angle to axial-fan." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/34215129762158203215.
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Cheng, Cheng-Hung, and 鄭政泓. "Effect of Blade Thickness, Solidities and Pitch Angle on the VAWT System." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/39677404704640421164.
Full textAbstract:
碩士國立中興大學
機械工程學系所
99
This study analyzes the effects of the blade thickness, the solidity and the pitch angle on the performance of VAWT system by Double Multiple Streamtube model (DMS model). The VAWT system includes three blades, situated 120°apart, with a chord length 0.1009m. The inflow wind speed is 10m/s, and the uncambered blades ( NACA0012, NACA0015 and NACA0018) are employed. The solidity varies from 0.07 to 0.3 by changing the rotating radius. The pitch angles of the blade are 0°and -2°. Some important results are concluded as follows: (1)When the tip speed ratio (TSR) is smaller than 3, the relative angle of attack are greater than the static stall angle during most of the rotating cycle. Thus, the cyclic tangential forces are mostly negative at the upwind and the downwind regions during each revolution, and result in a negative average torque. When the TSR is greater than 3, the relative angle of attack are smaller than the static stall angle, thus, the cyclic tangential forces are positive and increases in magnitude at the upwind region. On the other hand, those in the downwind region are negative and small in magnitude. This leads to a positive averaged torque during each revolution. (2)When the thickness of the uncambered airfoil increases, the critical tip speed ratio that produces the positive power and torque coefficients decreases. While the thickness decreases, both the maximum power and torque coefficients and the corresponding tip speed ratio increase. (3) The effect of solidity on the critical TSR that generates the positive torque and power coefficients is insignificant. As the solidity decreases, the changes of the magnitudes of maximum power and torque coefficients are minor; however, the corresponding TSR increases. (4)When the pitch angle is fixed at 0°, the operating ability at low TSR is better than that for the pitch angle of -2°. The maximum power and torque coefficients for the zero pitch angle are always greater than those for the pith angle of -2°.
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Chen, Guan Syu, and 陳冠旭. "Study of twist Angles for the Blades in Micro Horizontal Axis Wind Turbines." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/80496600164760091488.
Full textAbstract:
碩士長庚大學
機械工程學系
101
When a blade was designed without the consideration of the axial induction factor, the blade has a problem of excessive twist angle, which reduces the performance of the blade. Therefore, the purpose of this study is to find the optimized twist angle for the blade of a micro horizontal axis wind turbine and to fabricate the blade for performance verification. Firstly, we estimate the blade size based on the rated parameters. Secondly, we choose the airfoil type, chord length, and twist angle without considering the axial induction factor for each section of the blade. Then, the twist angle of the blade is characterized with a factor, p, which represents the degree of twist. The blades with varying p are analyzed with the Blade Element Momentum theory for their performance. After that, the power of coefficient CP of each section with independently varied twist angle is calculated and the combination of the twist angles with the highest CP is recorded. Finally, the blade with the optimal combination of twist angles is modeled with a 3D computer aided design software and fabricated. The model blades are installed on a vehicle mounted test-bench for performance tests. The results show that, the optimal design blade has a CP of 0.45 under a TSR (tip speed ratio) of 6.2. This CP is 0.05 higher than that of a non-optimal blade. More over, the maximum TSR becomes 10 from a previous value of 8, which shows a much stable output from the rotor can be expected. However, the optimal twisted blade has a higher start-up speed than that of the non-optimal bladed. This suggests that a pitch-adjustment mechanism is needed for the optimal blades so that the high performance would not be overlooked.
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Dong-LiTzeng and 曾東立. "Realization of a Pitch Angle Change Mechanism for Quadcopter Blades." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/tgknx6.
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Fang, Mei-Chih, and 方美智. "Simulation and analysis for the effect of axial fan blade angle on performance curve." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/13056195277959121480.
Full textAbstract:
碩士國立高雄應用科技大學
機械與精密工程研究所
99
Three axial-fan blade angles, i.e. fixed stagger angle, free stagger angle and horizontal inclination angle, are studied in this thesis by Taguchi Method. Influences of different fan angles on the performance, flow, pressure, torque, efficiency, noise and other characteristics of a fan are examined. In simulation, three axial-fan blade angles had used the Taguchi Method. Totally, 18 sets of simulation data are obtained. The data are analyzed through Signal-to-Noise Ratio (SNR) method, by using MINITAB software. For all of the control factors, set the quality characteristics to be either the larger is better or the smaller is better, and statistically analyze the influence of the every control factor on the fan characteristic. The results show that free stagger angle can significantly affect the performance curve of a fan. By the ANOVA (Analysis of Variance) can know to affect the flow rate of 19.46 %, static pressure of 59.24%, blade efficiency of 68.59% and the fan efficiency of 92.18%. In this study, a primary model is taken as an experimental model. It is compared with the experimental data, by using the Ansys CFD software to perform simulation. In the flow field simulation, the error of performance curve is less than 5% and the error of noise is within 10%. The accuracy of the simulation is significantly improved due to the CFD software and Taguchi Method, compared with the traditional method. It can reduce the more cost of materials, manpower and time.
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Yang, Yu-Sheng, and 楊裕勝. "Design and Fabrication of Pitch and Blaze-Angle Tunable Grating Device." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/46360517321306562043.
Full textAbstract:
博士國立清華大學
動力機械工程學系
97
This study aims at developing a novel pitch and blaze angle tunable grating device via Micro-Electro Mechanical Systems (MEMS) technologies. Grating is a powerful optical component for dispersing incident ray into specific angular direction corresponding to individual optical wavelength. After the first tunable grating device GLVTM was reported, tunable grating devices initiated a new region of optics since device design is variable, enabling easy construction of a flexible optical system. Pitch tunable gratings and blaze angle tunable gratings have been developed individually, but grating with these two tuning functions simultaneously has never been presented so far. In our group, we have been developing such gratings to bring more applications. According to the grating equation, the constructively interfered wavelength is in proportion to the grating pitch for the same diffraction angle. Thus we can tune the grating pitch and then detect all spectral lines sequentially by a photodetector. Besides, blaze angle tuning could adjust the intensity of the spectrum and enhance the grating performance. In our device, the pitch tuning function is carried out by bulk-micromachined thermal actuators, and the blaze angle tuning function is realized by electrostatic actuators. In order to enlarge the pitch tuning range, a novel thermal actuator is designed for our grating device. The experimental results show that the maximum output displacement of this actuator is over 316�慆 within 5.48W. The non-uniform stiffness results from non-uniform pre-strain on the slats, which comes from the quality control of our fabrication facility available. Thus the blaze angle of our grating device presently could only work with on-off two modes. Although the blaze angle is tuned by electrostatic force via non-linear pull-in phenomenon, it is theoretically possible to tune the blaze angle stably before the pull-in happens if the quality of the fabrication facility is good to achieve good structure pre-strain uniformity. Although this tunable grating device does not function well due to some fabrication limits of available facilities, experimental results verify that this is a workable tunable grating design with feasible fabrication process. If better fabrication facilities are available, the full features of the high-performance grating device could be realized soon and bring more applications.
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Chen, Bo-Jian, and 陳柏堅. "Analysis of the Blade Dihedral Angle on the Power Output Effect of the Wind Turbine." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/56200011635781843311.
Full textAbstract:
碩士國立屏東科技大學
機械工程系所
96
This research studies the effects of blade dihedral angle on the power output of a horizontal axis wind turbine. The purpose is to adjust the dihedral angle to reduce the power output of the blades, such that preventing damage the electric generator from over-speed the system. Both the blade element theory and momentum theory are used to develop the 3-dimensional blade shape, and then the Computational Fluid Dynamics (C.F.D.) method is introduced to resolve the flow-field details, and evaluate the performance of the system. The 3-dimensional blade shape is submitted to a mesh generator, GAMBIT, to create the mesh for the flow solver, which is FLUENT. NACA4415 airfoil is used for the blade sections. Various dihedral angles are used to make a map to determine the suitable angle that can make the wind turbine delivers the rated-power at a specified wind speed which is higher then the rated-wind speed. The results showed that the dihedral angle required at wind speed of 10 m/s is about 20°, at 11 m/s is about 25°, and at 12 m/s is about 30°. Therefore, the model of adjusting the output power by regulate the turbine blade dihedral angle suggested in this work is proved feasible.
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Huang, Hui-Ren, and 黃暉仁. "Research on the influence of blade twist angle on the performance of horizontal-axis wind turbine system." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/56091916818386588808.
Full textAbstract:
碩士中原大學
機械工程研究所
101
This paper conducts a study on the performance of horizontal-axis wind turbine system. The purpose is to investigate the influence of blade twist angle on its mechanical energy, electrical energy, and conversion efficiency for different wind speeds and blade numbers. First, we present blades of different twist angles by using industrial plastics and generate different wind conditions by setting a wind tunnel testing system. Then, we measure the rotational speed, torque, and power generation, so as to obtain the horizontal-axis wind turbine system performance data at different wind speeds and blade numbers. Finally, we use STAR CCM+ for simulation analyze the blade surface pressure and velocity fields, so as to realize the cause of dynamic phenomena. It is found that when the value of the blade twist angle increases at a fixed wind speed and blade number, all the mechanical energy, electrical energy, and conversion efficiency increase to their maxima and then decrease. This critical twist angle can be magnified by increasing the wind speed and blade number.
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"Effect of blade surface roughness on profile loss and exit angle in a rectilinear steam turbine cascade." Thesis, 2002. http://localhost:8080/iit/handle/2074/5137.
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Huang, Guan-Ming, and 黃冠銘. "Performance Analysis of an Innovative Vertical Axis Turbine Consisting of Variable-Angle Blades." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/32726065909836545869.
Full textAbstract:
碩士國立高雄海洋科技大學
造船及海洋工程研究所
103
The aim of this study is to investigate the performance of a variable-angle-blade turbine (VABT) of ocean current and tide energy application. Because the vertical axis turbine can be driven by multi-directional current flow, it is suitable to extract ocean current and tide the tide energy with using vertical axis turbine. This study reveals an innovative vertical axis turbine which consists of four variable-angle-blades to obtain a higher energy conversion performance. By the interaction of the connecting rods between these blades, the torque of pressure face increases and the resistance of suction face reduces. Therefore the overall performance of the VABT for current energy conversion can be increased. The commercial Computer fluid dynamics (CFD) code, Ansys_Fluent is used to simulate the streamline and pressure distributions and to calculate the torque of VABT. The power coefficient of the VABT is obtained numerically to evaluate the performance with various rotating speed. The maximal power coefficient of the VABT and corresponding optimal tip speed ratio are also obtained. Furthermore, the performance comparisons of the power coefficients for the VABT and traditional fixed-angle-blade turbine are carried out. The results show that the optimal power coefficient of VABT is 40.4% higher than that of FABT as tide current speed at 1 m/s. Moreover, the effects of the parameters, which are blade number, the depth, height and radius of blades on performances for the VABT are also investigated. In addition, the preliminary test of prototype is illustrated experimentally to validate the feasibility of the VABT. The findings of this study are expected to provide a favorable foundation in implementing for the vertical axis turbine of the tide and ocean current.
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Wen, Ren-Fang, and 溫仁方. "The Design, Development and Testing of Small Wind Turbine Blades Changeable Angle of attack." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/t69r5s.
Full textAbstract:
碩士明道大學
材料與能源工程學系碩士班
105
In order to improve the energy shortage and global warming issues, people work heart to create a lot of renewable energy, in many renewable energy project, the technology of Wind Turbine is mature and have good economic efficiency. Wind Power Device grows very fast in the world, since 1990, the average value of annual growth is 25%, it will be stable to grow in the future and be the most important of energy, the Carbon reduction policy is one of the goals in our country to evolve renewable energy. Large Wind Turbine is saturated in development of Wind energy using effectiveness, but medium-small Wind Turbine has a lot of space for development, in order to develop and popularize medium-small wind turbine to the people, that is our purpose. Our design is a variable-angle blades using Hook’s Law spring to change the angle, the max speed can be more large, in high speed, our Axis can make the blade-angle stable in rated revolution to protect Generator, this design can make the blade and Generator more durable, design Anti strong winds Blade, lower damage for Blade and Generator also make the repairing expensed and cost lower, study safety structure and well-power of Small Wind Turbine in different wind speed to develop simple mechanical device. During the research, there are many parameters, so our research use actual test to record the result, when we got preliminary result, we joined “2016National wind energy and marine energy creative practice competition” in National Taiwan Ocean University, we earn very precious experience, and then we keep working hard and get better, joined “2016National college production innovation implementation competition” in National Changhua University of Education, we got Outstanding Award, we also had been invited to “2016Best Source Energy Technology creative exhibition” in National Science and Technology Museum. Had many kind of development experience, our research designed the wind turbine have a lot of affirmation, we have do well in security protection mechanism of Wind Turbine in variable axis and spring, the security protection mechanism turn on successfully in 8m/s with K=0.9 spring, according to the derivation of lab data, we predict the security protection mechanism is working in 11m/s with K=1.0 spring, the blades speed increase and revolution keeps stable, keep generating electricity stably in rated revolution, we also upgrade the power range of Wind Turbine in the safety situation, giving the wind turbine a good innovation and development.
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Ming-Hua, Kang, and 康明華. "Study on pitch angle adjustment of wind turbine blades for a specified power output." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/11833967778473350418.
Full textAbstract:
碩士國立屏東科技大學
機械工程系所
95
In recent years, we have been facing gradual shortages of fossil fuels; as a result, prices have risen rapidly. Various governments have been doing their utmost to seek, and develop, alternative source of energy. At present, the wind turbine has the most advanced technology among all of the alternative energy devices, as well as low pollution levels and limitless regeneration. In this paper, we show the design of a wind turbine blade that can best generate electric power at a specified design conditions, and how many degrees should the pitch angle of this wind turbine blade need to be adjusted for stable output at different wind velocity. This paper utilizes blade element method to built and analyze model. The NACA-4415 airfoil was chosen as the study’s designed wind turbine blade. We show how to adjust section pitch angle as well as angle of attack, by analyzing various wind velocity, to keep stable output of the blade. The result indicates that too high velocity variation result in high efficiency down. Single adjusting way is not good to deal with high velocity change. Using average wind velocity as the rated design base and supplement other electric resource might be the better solution for creating a higher eficiency power supply system.
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Hsu, Chi-Wei, and 許自瑋. "The Study on the Performance of the Wind Turbine Blades with Variable Pitch Angle Mechanism." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/10490114827228708751.
Full textAbstract:
碩士長庚大學
機械工程學系
99
As the rise of environmental consciousness, renewable energy becomes increasingly more prevalent, and wind energy is being used extensively for generation of electricity. Small-sized horizontal-axis wind turbines (SHAWT) offer great advantages in off grid system in rural and remote areas. However, present designs of SHAWT have some defects, such as high startup speed, fixed pitch angle and additional safety device for strong wind, etc. In order to solve these problems, we build wind turbine blades with variable pitch angle mechanism that have high wind speed efficiency, stall control and low startup speed simultaneously. The purpose of this research was to examine the performance of newly developed mechanism. In theoretical analysis, we programmed algorithms based on the Blade Element Momentum (BEM) theory with C programming language to predict the blades performance. And we also development Equation for wind turbine blades with variable pitch angle mechanism, to obtain the relationship between the blades rotational speed, and the pitch-angle variation, v. In experimental design, we establish a car-mounted experimental bench to gain performance data of the blades, which allows us to simulate variable wind conditions by controlling vehicle speed. A magnetic particle brake provides shaft load, and rotational torque sensor used for rotation speed and load measurement. An anemometer is used for wind speed measurement. All the data are recorded in a portable data logger for further analysis. The test result shows that the experimental bench is capable of measuring instantaneous wind speed, rotational speed, and shaft load of the turbine blades. Moving average method was applied to analog data for measure error reduction. The experimental data (Power-) are greatly consistent with the theoretical data, but due to the dynamic stall and the inevitable gust winds, the experiment data has circulatory phenomenon. Furthermore, current design of the safety pin and the pin hole may induce an unsteady turbine performance when Tip Speed Ratio (TSR) > 5. To solve this problem, we illustrate three feasible methods for future research.
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Lin, Fang-Jin, and 林昉瑾. "The Coupling Design and Analysis of Chord Length and Twist angle of Helicopter Rotor Blade in Unsteady Wake Dynamic System." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/72078042661563400276.
Full textAbstract:
碩士淡江大學
航空太空工程學系
87
Optimum design of two different design variables, chord length and twist angle, through an unsteady aerodynamic system will be considered in this study. Besides, this paper also discuss the coupling effect between chord length and twist angle, and apply wake dynamics, areodynamics and optimality criterion theory to obtain the optimum configuration of rotor blades. The purpose of this study is to obtain a helicopter blades' chord length and twist angle which to minimize the power output and also maintain the lift force in a misson. Because design variable doubles and couples so that the problem becomes complicated, an improve move limit with Bezier curve technique will be implemented in optimal program to overcome these effect. The BELL UH-1H helicopter rotor blades will be redesign by optimum design program exactly and steadily. The result of new design rotor blade will compare with the original rectangular rotor blade in numerical examples.
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SAMADDER, SOUVIK. "A NUMERICAL STUDY ON COMBINED EFFECT OF DEFLECTOR PLATE, TWIST ANGLE OF BLADES, AND TIP SPEED RATIO ON THE PERFORMANCE OF SAVONIUS HYDROKINETIC TURBINE." Thesis, 2022. http://dspace.dtu.ac.in:8080/jspui/handle/repository/19132.
Full textAbstract:
Savonius Hydrokinetic Turbine (SHT) is a small-scale renewable energy
source that is a sustainable solution for remote areas and rural electrification. The
current research work establishes a numerical study on combined effect of deflector
plate (no deflector, deflector at 90°, deflector at 45°), twist angle of blades (0°, 12.5°,
25°), and tip speed ratio (0.5 to 1.5) on the turbine efficiency in terms of power
coefficient (Cp) using CFD simulation considering a realizable k-ε turbulence model.
A total of 99 simulations were performed considering all the above different
conditions. To validate the results, simulations were compared with the results of a
previous study having no deflector plate. It has been identified that SHT with blade
twist angle of 12.5° and deflector plate at 90° produces highest power coefficient as
0.364 at tip speed ratio of 0.9 and 0.5 m/s water velocity. Similarly, SHT having a
blade twist angle of 25° with deflector plate at 90° yields the highest torque coefficient
as 0.454 at a TSR of 0.5. It was observed that Cp increases by an average 15% for SHT
having blade twist and deflector plate as compared to SHT without blade twist and
deflector plate.
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Jhang, Wei-Ciao, and 張惟喬. "Analysis and Diagnosis of Wind Turbine Blades-Angle Abnormality Based on Anti-noise Hilbert-Huang Transform and Genetic Glowworm Swarm Optimization." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/aayem9.
Full textAbstract:
碩士中原大學
電機工程研究所
102
This study proposes an anti-noise Hilbert-Huang transform (AHHT) approach with the aim to enhance the angle-detection capability of wind turbine blades. Artificial neural network (ANN) are applied the features to recognize the blades faults. First, this study proposes a novel model of blades unbalanced signal analysis based on the anti-noise Hilbert–Huang transform (AHHT). The AHHT combines a particle swarm optimization (PSO) algorithm with an Hilbert-Huang transform(HHT) based on ensemble empirical mode decomposition(EEMD). The AHHT model is used to slove interference problems of signals in interference environments. Second, this thesis extract the feattures of current signals in the signal analysis method, and input these features to a genetic glowworm swarm optimization (GGSO) to select the effective features subset of features set. The GGSO combines a glowworm swarm optimization (GSO) algorithm with an genetic algorithm (GA). Finally, this thesis utilizes fast Fourier transform (FFT), multi-resolution analysis (MRA), HHT and AHHT, for blades unbalanced analysis. The results indicate that the AHHT has the best detection accuracy. Moreover, the inferior features may cause the interference phenomenon, and subsequently, the detection accuracy of probabilistic neural network (PNN) decline significantly. This study utilizes GGSO and sequential forward selection (SFS), for feature selection problem. The results indicate that the GGSO has the best detection accuracy.
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Dyson, Thomas Earl. "Effects of hole pitch variation on overall and internal effectiveness in the leading edge region of a simulated turbine blade with heat flux measurements." Thesis, 2010. http://hdl.handle.net/2152/ETD-UT-2010-05-1215.
Full textAbstract:
In this study, the cooling of a simulated blade under increasing pitch between holes was examined. The change in non-dimensional surface temperature, phi, was measured experimentally to quantify this performance loss. This critical quantification of the sensitivity of cooling to pitch between holes has not been studied previously. A range of blowing ratios and angles of attack were tested. Data are presented in terms of the laterally averaged phi, and in terms of the minimum phi, arguably more important from a design perspective. Increasing the pitch 13% produced no measureable change using either parameter. An increase of 26% in pitch produced only a 4% loss in lateral averages, while some hot points dropped by 10%. These small changes are due to compensating effects of increased internal and through-hole convective cooling. A limit to these effects was shown when increasing pitch 53%. While performance loss in the average was still relatively small at 15%, the minimum phi decreased by 27%.
Heat flux gauges were used to gather data on the internal and external surface. The internal impingement used in this study represents a more accurate representation of internal cooling for an actual engine part than has been previously studied, providing a starting point for exploring the differences between engine configurations and those generally investigated in the literature. External heat flux measurements were used to measure the ratio of heat flux with and without film cooling. These results call into question the use of the net heat flux reduction parameter, which is commonly used to quantify overall film cooling performance.text
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Oberholster, Abraham Johannes. "The application of Eulerian laser Doppler vibrometry to the on-line condition monitoring of axial-flow turbomachinery blades." Thesis, 2010. http://hdl.handle.net/2263/25794.
Full textAbstract:
The on-line condition monitoring of turbomachinery blades is of utmost importance to ensure the long term health and availability of such machines and as such has been an area of study since the late 1960s. As a result a number of on-line blade vibration measurement techniques are available, each with its own associated advantages and shortcomings. In general, on-blade sensor measurement techniques suffer from sensor lifespan, whereas non-contact techniques usually have measurement bandwidth limitations. One non-contact measurement technique that yields improvements in the area of measurement bandwidth is laser Doppler vibrometry. This thesis presents results and findings from utilizing laser Doppler vibrometry in an Eulerian fashion (i.e. a fixed reference frame) to measure on-line blade vibrations in axial-flow turbomachinery. With this measurement approach, the laser beam is focussed at a fixed point in space and measurements are available for the periods during which each blade sweeps through the beam. The characteristics of the measurement technique are studied analytically with an Euler-Bernoulli cantilever beam and experimental verification is performed. An approach for the numerical simulation of the measurement technique is then presented. Associated with the presented measurement technique are the short periods during which each blade is exposed to the laser beam. This characteristic yields traditional frequency domain signal processing techniques unsuitable for providing useful blade health indicators. To obtain frequency domain information from such short signals, it is necessary to employ non-standard signal processing techniques such as non-harmonic Fourier analysis. Results from experimental testing on a single-blade test rotor at a single rotor speed are presented in the form of phase angle trends obtained with non-harmonic Fourier analysis. Considering the maximum of absolute unwrapped phase angle trends around various reference frequencies, good indicators of blade health deterioration were obtained. These indicators were verified numerically. To extend the application of this condition monitoring approach, measurements were repeated on a five-blade test rotor at four different rotor speeds. Various damage cases were considered as well as different ELDV measurement positions. Using statistical parameters of the abovementioned indicators as well as time domain parameters, it is shown that with this condition monitoring approach, blade damage can successfully be identified and quantified with the aid of artificial neural networks.Thesis (PhD)--University of Pretoria, 2010.
Mechanical and Aeronautical Engineering
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Scheepers, Gerard. "An experimental and numerical study of heat transfer augmentation near the entrance to a film cooling hole." Diss., 2008. http://hdl.handle.net/2263/27590.
Full textAbstract:
Developments regarding internal cooling techniques have allowed the operation of modern gas turbine engines at turbine inlet temperatures which exceed the metallurgical capability of the turbine blade. This has allowed the operation of engines at a higher thermal efficiency and lower specific fuel consumption. Modern turbine blade-cooling techniques rely on external film cooling to protect the outer surface of the blade from the hot gas path and internal cooling to remove thermal energy from the blade. Optimization of coolant performance and blade-life estimation require knowledge regarding the influence of cooling application on the blade inner and outer surface heat transfer. The following study describes a combined experimental and computational study of heat transfer augmentation near the entrance to a film-cooling hole. Steady-state heat transfer results were acquired by using a transient measurement technique in an 80 x actual rectangular channel, representing an internal cooling channel of a turbine blade. Platinum thin-film gauges were used to measure the inner surface heat transfer augmentation as a result of thermal boundary layer renewal and impingement near the entrance of a film-cooling hole. Measurements were taken at various suction ratios, extraction angles and wall temperature ratios with a main duct Reynolds number of 25×103. A numerical technique, based on the resolution of the unsteady conduction equation, using a Crank-Nicholson scheme, was used to obtain the surface heat flux from the measured surface temperature history. Computational data was generated with the use of a commercial CFD solver.Dissertation (MEng)--University of Pretoria, 2008.
Mechanical and Aeronautical Engineering
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Engelbrecht, Gerhardina Cornelia. "Cognitive dissonance in trauma: the conflict between belief, autobiographical memory and overt behaviour." Diss., 2015. http://hdl.handle.net/10500/19956.
Full textAbstract:
Text in EnglishThis research was aimed at giving a voice to three women, who are constructed as having had a traumatic event recalled from their autobiographical memory. To achieve this objective an epistemological framework of social constructionism was used to investigate autobiographical memory recall of trauma. Three in-depth interviews were conducted with participants who constructed themselves as having had a traumatic event. A case study approach was used to gain access to the information and to compare themes. The research explored the way in which dissociation, voluntary thought suppression, minimisation and outright denial enabled the three participants to alter unbearable memories through the use of recurring themes. To interpret these stories the content of the themes was analysed using thematic content analysis. The participants represented different cultures, languages and religions. In sharing their symptoms this did not necessarily mean they attached the same meaning to a specific theme, as individual meaning-making corresponded to the individual‟s background and history and their perception of the trauma. The stories related by the three participants revealed a shattered worldview that brought them into opposition with community norms and standards, which the narrators experienced as silencing and judgemental. In this regard the researcher‟s aim was to generate information from the participants themselves. This inquiry into the personal trauma stories and meanings suited a qualitative research approach, a form of methodology that allowed personal insight into the meanings the three participants attributed to their trauma and the autobiographical recall of trauma. At the same time it allowed a co-constructed reality to take shape between the researcher‟s reality and the participant‟s reality, always acknowledging the importance of their being the expert of their own individual trauma memory. This is in contrast to a quantitative approach which focuses on numbers to quantify the results; a qualitative approach on the other hand is a personal, rich information-gathering tool that takes into account the emotions and meaning-making of each individual story without any intention to generalise the information gathered to a larger population It is hoped that through this research there is a realisation that although trauma victims share symptoms, the meaning-making of the individual attached to this trauma is influenced by their society and history within their respective environments.
Psychology
M.A. (Psychology)