<div>The ambient pressure fluctuations within a wind tunnel test environment can severely affect the boundary layer transition witnessed on test articles The Boeing/AFOSR Mach 6 Quiet Tunnel was designed to minimize these fluctuations, also referred to as noise, and is the world's premier facility for studying hypersonic boundary layer transition in a quiet flow environment. All experiments performed for this work were conducted at this facility.</div><div><br></div><div> </div><div> The freestream flow field of this tunnel has been characterized multiple times since its creation, however an extensive three-dimensional spatial sweep has never been conducted. A pitot rake model was designed to allow for an extensive spatial survey of tunnel noise. This model created measurement capabilities that were previously unknown to the BAM6QT facility, including the ability to take concurrent freestream pitot probe measurements. The performance of this new measurement method was evaluated, and suggestions for future verification tests are made. The pitot rake appears to suffer from probe-probe interactions in certain configurations, and has demonstrated variation in measurements that depends on the individual sensor used.</div><div><br></div><div> </div><div> This new measurement apparatus was used to investigate the effect that cavities in the tunnel wall created by the installation of new optical windows had on the freestream noise level. A control dataset corresponding to a perfectly conformal tunnel wall was not collected during this work. The experiments conducted provide evidence that the tunnel wall cavities do increase the noise downstream of their location by approximately 100%, however a control dataset is needed to verify this finding.</div><div><br></div><div> </div><div> In addition to tunnel characterization, a novel flat plate model was evaluated for use in the BAM6QT. This model was intended for use as a platform for observing second mode instability growth. These experiments show that the initial flat plate geometry proved incompatible with the BAM6QT as the tunnel could not achieve nominal flow conditions with the model installed. The flat plate model was streamlined to rectify the startup issue, but no evidence of the second mode instability was found. A 2.5° half angle cone is being designed to replace the flat plate model as a platform for the continuation of this project.</div>

No description available.

Temporally developing direct numerical simulations (T-DNS) are performed and validated for bypass transition of a zero pressure gradient flat plate boundary layer to understand the interplay between pressure-strain terms and flow instability mechanisms, and to propose and validate a phenomenological hypothesis for the identification of a robust transition onset marker for use in transition-sensitive Reynolds-averaged Navier-Stokes (RANS) computational fluid dynamics (CFD) simulations. Results show that transition initiates at a location where the slow pressure-strain term becomes more dominant than the rapid term in the pre-transitional boundary layer region. The slow pressure strain term is responsible for the transfer of turbulence energy from the streamwise component to other components while the rapid pressure strain term counteracts with the slow term in the pre-transitional regime before transition onset akin to a shear sheltering like effect. The relative magnitudes of the slow and rapid terms thus provide a basis for the development of physically meaningful large-scale parameters that can be used as a transition onset marker for Reynolds averaged Navier-Stokes RANS simulations.

No description available.

No description available.

Several nuclear research reactors use or are planned with cores containing flat-plate- type fuel elements. The nuclear fuel is contained in parallel plates that are separated by narrow channels through which the fluid flows to remove the heat generated by fission reactions. One of the problems of this fuel element design is the mechanical stability of the fuel plates. High-velocity coolant flowing through the channels can cause large deflections of these plates leading to local overheating, structural failure or plate collapse. As a consequence, the safe operation of the reactor may be affected. In this work, a numerical fluid-structure interaction study was conducted for evaluating the mechanical stability of nuclear fuel plates under axial flow conditions. Five different cases were analyzed. In all cases, the system consisted of two fuel plates bounded by fluid channels but, in case 5, a support comb at the leading edge of the plates was inserted. The pressure loadings caused by the fluid flow were calculated using a Computational Fluid Dynamics model created with ANSYS CFX. The structural response was determined by means of a Finite Element Analysis model generated with ANSYS Mechanical. Both models were coupled using the two-way fluid-structure interaction approach. The results from Case 1 allowed proposing a methodology to predict the critical velocity of the assembly without an inlet support comb. The maximum deflection of the plates was detected at their leading edges. It was detected that, for flow rates in the channels less than a certain value, the maximum deflection increased linearly with the square of the coolant velocity. In contrast, for greater flow rates, a nonlinear behavior was observed. Therefore, that fluid velocity was identified as the critical velocity of the system. Besides, above the critical velocity, an extra deflection peak was observed near the trailing edge of the plates. In cases 2, 3 and 4, the influence of manufacturing deviations and the change of materials properties due to the increment of temperature on the critical velocity was investigated. With these conditions, the critical velocity of the system was found at lower values. Lastly, in Case 5, the effectiveness of using a support comb at the leading edge of the plates was investigated. The results showed that the static divergence at the inlet end is effectively eliminated with the installation of the comb. In addition, the flow-induced deflections along the length of the plates were significantly diminished with the comb. / Muitos reatores nucleares de pesquisa usam ou são planejados com elementos combustíveis tipo placas planas. O combustível nuclear está contido em placas paralelas que são separadas por canais estreitos através dos quais o fluido refrigerante passa para remover o calor gerado pelas reações de fissão. Um dos problemas deste tipo de elemento combustível é a estabilidade mecânica das placas de combustível. O líquido refrigerante a alta velocidade pode causar deflexões excessivas dessas placas, bloqueando o canal de escoamento e levar ao superaquecimento nas placas, falha estrutural ou colapso da placa. Como consequência, a operação segura do reator pode ser afetada. Neste trabalho, foi realizado um estudo numérico de interação fluido-estrutura para avaliar a estabilidade mecânica de placas de combustível nuclear sob condições de fluxo axial. Cinco diferentes casos foram analisados. Em todos os casos, o sistema consistiu em duas placas de combustível delimitadas por canais de fluido, mas, no caso 5, um pente de suporte na borda de ataque das placas foi inserido. As cargas de pressão causadas pela vazão foram calculadas usando um modelo de Dinâmica dos Fluidos Computacional, criado com ANSYS CFX. A resposta estrutural foi determinada por meio de um modelo de elementos finitos, gerado com ANSYS Mechanical. Os modelos foram acoplados usando a abordagem de interação fluido-estrutura bidirecional. Os resultados do Caso 1 permitiram propor uma metodologia para prever a velocidade crítica do sistema sem o pente de suporte. A deflexão máxima das placas foi observada em suas bordas de ataque. Foi detectado que, para velocidades nos canais inferiores a um determinado valor, a deflexão máxima aumentava linearmente com o quadrado da velocidade do líquido refrigerante. Em contraste, para maiores vazões, um comportamento não linear foi observado. Portanto, essa velocidade do fluido foi identificada como a velocidade crítica. Além disso, acima da velocidade crítica, um pico extra de deflexão foi observado próximo à borda de saída das placas. Nos casos 2, 3 e 4, a influência dos desvios de fabricação e da alteração das propriedades dos materiais devido ao incremento de temperatura na velocidade crítica foi investigada. Sob essas condições, a velocidade crítica foi encontrada a valores mais baixos. Por fim, no Caso 5, a eficácia do uso do pente de suporte na borda de entrada das placas foi estudada. Os resultados mostraram que a divergência estática na extremidade de entrada foi efetivamente eliminada com a instalação do pente. Além disso, as deflexões induzidas pelo fluido ao longo do comprimento das placas foram significativamente diminuídas com o pente.

Submitted by Marilene Donadel (marilene.donadel@unioeste.br) on 2019-03-11T22:27:03Z No. of bitstreams: 1 Camila_Hinterholz_2018.pdf: 6217665 bytes, checksum: a00620aa466c15bb7a0ac5126e8c3614 (MD5) / Made available in DSpace on 2019-03-11T22:27:03Z (GMT). No. of bitstreams: 1 Camila_Hinterholz_2018.pdf: 6217665 bytes, checksum: a00620aa466c15bb7a0ac5126e8c3614 (MD5) Previous issue date: 2018-11-13 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The objective of this study was to develop a laboratory-scale photobioreactor (PBR) capable of obtaining microalgae cultures with high cell density. For this, the cultivation of Poterioochromonas malhamensis was evaluated in a flat-plate PBR, built with a useful volume of 10 L. The microalga strain was isolated from an artificial lake from Toledo – PR. The whole study was based on the System Analysis Theory, in which the research was divided into four hierarchical levels. In the first level, the mass transfer (MT) parameters were evaluated by means of a fractionated factorial design (FFD) considering four factors: gas inlet flow (Qgas), CO2 in the inlet gas (φCO2), antifoam concentration (CAE) and salinity of the medium (φsal), whose adjustable values may represent the MT for the responses K_L a_(O_2 ),〖 K〗_L a_(CO_2 ),O_2^eq e CO_2^eq. Thus, the parameters K_L a_(O_2 ) (14.88 to 79.32 h-1) and K_L a_(CO_2 ) (0 to 125.40 h-1) were verified experimentally, as well as the equilibrium concentration variations: O_2^eq (37.33 to 99.66%) and CO_2^eq (0 to 98.33%) respectively, relative to the equilibrium values of the species dissolved in pure water. Still in the first level, the Euler-Euler model was used for the study of the fluid dynamics inside the PBR, with the software Comsol®, being evaluated three configurations: PBRA – without disperser; PBRB – with simple bubble disperser; and PBRC – with perforated disperser, whose bubble dispersion proposal ensured a higher frequency of the light-dark cycles, according to the simulations of water and bubbles flows performed in mono and multiphase systems, respectively. The influence of the bubble dispersion module on cell growth was verified experimentally with PBRA and PBRC runs, which showed a 175% increase in biomass production (15.7 g L-1) with use of PBRC. In the second hierarchical level, the tolerance of the strain to the adjustable conditions of the system was studied: Qgas, φCO2, in addition to temperature, lighting conditions, nutrient concentrations and organic carbon, using the pulse technique. Within the evaluated ranges, the results did not show inhibition of growth, but was accentuated in values above 30 °C. Also, at this level, assuming the production of 1 g L-1 biomass, M-8 and BG-11 media were optimized by linear mathematical programming, whose objective function subjected to constraints based elemental composition of the biomass. Therefore, the original and optimized media were evaluated regarding biomass production, as well as protein, carbohydrate, lipid and pigment chlorophyll-a, chlorophyll-b and carotenoids content of cells. ANOVA indicated the best medium for the production of biomass (M-8), whose optimized values were prepared in the nitrogen source evaluation cultures. In these, three inorganic sources – NH4NO3, NaNO3 and KNO3; and an organic – urea were compared, and it was verified by ANOVA that the most appropriate source for the production of biomass was urea. In the third hierarchical level, a growth model was proposed based on mass balances and the definitions of specific transformation velocity, conversion definition, CO2 and O2 dissociation reactions in water and Henry's Law. After applying the phenomenological modeling of unstructured and non-segregated models, a set of stoichiometric equations was built, which were used to evaluate kinetic models obtained from the literature, by which the influence of light, dissolved CO2 and O2, pH and temperature on cell growth. Using the results obtained at previous levels, the fourth-level study indicated that the simplified model proposed to describe the experimental data of Poterioochromonas malhamensis culture in closed PBR (cell growth, CO2 consumption in the gas phase, and variation in the pH of the medium) was adequate, whose simulations were also satisfactory for the consumption of the inorganic dissolved carbon species, as well as for the mass transfer between the phases. In this step, 32 kinetic and stoichiometric parameters were estimated in the fit of the proposed model to the experimental data, through an algorithm based on the Genetic Algorithms implemented in the software Maple®. Therefore, this study presented the use of the perforated bubble disperser module coupled to the proposed PBR, which allowed the achievement of what is characterized by ultra-high density culture, since ≈ 15 g L-1 of biomass were produced by the culture of P. malhamensis. It was also highlighted the possibility of optimizing important conditions for biomass cultivation, as well as for the design of PBRs, through the collection of experimental data, associated to appropriate statistical methodologies of evaluation and to kinetic and fluid dynamics modeling, according to the General Theory of Systems applied. / Este estudo teve por objetivo o desenvolvimento de um fotobiorreator (PBR) em escala laboratorial capaz de obter culturas de microalgas com alta densidade celular. Para isto, avaliou-se o cultivo de Poterioochromonas malhamensis em um PBR de placas planas, construído com volume útil de 10 L. A cepa desta microalga foi isolada de um lago artificial de Toledo – PR. Todo o estudo foi baseado na Teoria Geral de Sistemas em que se dividiu a pesquisa em quatro níveis hierárquicos. No primeiro nível avaliaram-se os parâmetros da transferência de massa, por meio de um planejamento fatorial fracionado (PFF) considerando-se quatro fatores: vazão de entrada de gás (Qgás), CO2 no gás de entrada (ϕCO2), concentração de antiespuma (CAE) e salinidade do meio (ϕsal), cujos valores ajustáveis podem representar a TM para as respostas K_L a_(O_2 ),〖 K〗_L a_(CO_2 ),O_2^eq e CO_2^eq. Com isso, foram verificados experimentalmente os parâmetros: K_L a_(O_2 ) (14,88 a 79,32 h-1) e K_L a_(CO_2 ) (0 a 125,40 h-1), bem como as variações de concentração das espécies dissolvidas no equilíbrio: O_2^eq (37,33 a 99,66%) e CO_2^eq (0 a 98,33%), respectivamente relativo aos valores de equilíbrio das espécies dissolvidas em água pura. Ainda no primeiro nível, o modelo de Euler-Euler foi utilizado para o estudo da fluidodinâmica dentro do PBR, por meio do software Comsol®, sendo avaliadas três configurações: PBRA – sem dispersor; PBRB – com dispersor de bolhas simples; e PBRC – com dispersor perfurado, cuja proposta de dispersão de bolhas garantiu maior frequência dos ciclos claro-escuro, de acordo com as simulações de fluxos de água e de bolhas realizadas em sistema mono e multifásico, respectivamente. A influência do módulo dispersor de bolhas sobre o crescimento celular foi verificada experimentalmente por ensaios feitos com o PBRA e o PBRC, a partir dos quais se verificou o aumento de 175% na produção de biomassa (15,7 g L-1) com a utilização do PBRC. No segundo nível hierárquico, foi estudada a tolerância da cepa frente às condições ajustáveis do sistema: Qgás, ϕCO2, CAE, além de temperatura, condições de iluminação, e concentrações de nutrientes e carbono orgânico, utilizando-se a técnica de pulsos. Dentro das faixas avaliadas, os resultados não mostraram inibição do crescimento, porém este foi acentuado em valores acima de 30°C. Também, neste nível, admitindo-se a produção de 1 g L-1 de biomassa, os meios M-8 e BG-11 foram otimizados por programação matemática linear cuja função objetivo sujeita a restrições baseadas na composição elementar da biomassa. Com isso, os meios originais e otimizados foram avaliados quanto à produção de biomassa, e ao teor de proteínas, carboidratos, lipídeos e pigmentos clorofila-a, clorofila-b e carotenoides. A ANOVA indicou o melhor meio para a produção de biomassa (M-8), cujos valores otimizados foram preparados nos cultivos de avaliação da fonte de nitrogênio. Nestes, três fontes inorgânicas – NH4NO3, NaNO3 e KNO3; e uma orgânica – ureia foram comparadas, verificando-se pela ANOVA que a fonte mais indicada para a produção de biomassa foi a ureia. No terceiro nível hierárquico, foi proposto um modelo de crescimento com base em balanços de massa e nas definições de velocidade específica de transformação, definição de conversão, reações de dissociação do CO2 e O2 em água e a Lei de Henry. Após a aplicação da modelagem fenomenológica de modelos não estruturados e não segregados, obteve-se um conjunto de equações estequiométricas, que foram utilizadas para avaliar modelos cinéticos obtidos da literatura, pelos quais se avaliaram a influência da luz, CO2 e O2 dissolvidos, pH e temperatura sobre o crescimento celular. Utilizando-se os resultados alcançados nos níveis anteriores, o estudo do quarto nível indicou que o modelo simplificado proposto para descrever os dados experimentais de cultivo de Poterioochromonas malhamensis em PBR fechado (crescimento celular, consumo de CO2 na fase gasosa, e variação no pH do meio) foi adequado, cujas simulações mostraram-se satisfatórias também para o consumo das espécies de carbono inorgânico dissolvido, bem como para a transferência de massa entre as fases. Nesta etapa, 32 parâmetros cinéticos e estequiométricos foram estimados no ajuste do modelo proposto aos dados experimentais, por meio de um algoritmo baseado nos Algoritmos Genéticos implementado no software Maple®. Portanto, o presente estudo apresentou a utilização do módulo dissipador de bolhas perfurado acoplado ao PBR proposto, o que permitiu a obtenção do que se caracteriza por cultura de densidade ultra alta, uma vez que ≈15 g L-1 de biomassa foram fornecidos pelo cultivo de P. malhamensis. Destacou-se, também, a possibilidade da otimização de condições importantes para o cultivo de biomassa, bem como para o projeto de PBRs, por meio do levantamento de dados experimentais, associado às adequadas metodologias estatísticas de avaliação e à modelagem cinética e fluidodinâmica, conforme se verificou pela Teoria Geral de Sistemas aplicada.

Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2019-03-13T15:52:53Z No. of bitstreams: 1 José Maurício de Moura Leitão_.pdf: 2775602 bytes, checksum: b3838f30f897415be8b7b629885f3a15 (MD5) / Made available in DSpace on 2019-03-13T15:52:53Z (GMT). No. of bitstreams: 1 José Maurício de Moura Leitão_.pdf: 2775602 bytes, checksum: b3838f30f897415be8b7b629885f3a15 (MD5) Previous issue date: 2018-11-21 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Eficiência e economia na produção de energia são fatores-chave no desenvolvimento social e econômico de um país. A energia solar é uma fonte de energia limpa e renovável, utilizada em sua maior parte para o aquecimento de água por meio de coletores solares. Nos últimos 15 anos, os coletores solares planos vêm, devido ao apelo mundial para o uso de materiais mais facilmente recicláveis e ao baixo custo, utilizando cada vez mais materiais poliméricos, substituindo os convencionais. Para analisar quais materiais poliméricos podem ser usados em coletores solares planos, este trabalho realizou um teste de intemperismo acelerado nos materiais polissulfona (PSU), polietileno (PE) e policarbonato (PC). Destacam-se o PSU e o PE. O PSU tem o melhor resultado em relação ao nível de degradação, pois sua cadeia polimérica é composta por anéis aromáticos e fortes ligações de carbono, enxofre e oxigênio dentro da espinha dorsal do polímero. Adicionalmente, foram realizadas análises do infravermelho nos materiais envelhecidos na câmara de intemperismo acelerado pelo método ATR ou refletância total atenuada. Eles apresentaram, na cadeia molecular, pequenas mudanças nos espectros na região do infravermelho à medida que o tempo exposto na câmara de envelhecimento aumentava. Por fim, foi desenvolvida uma simulação numérica de um coletor solar plano na plataforma ESS (Engineering Equation Solver) em que foi simulado o efeito do número de tubos no absorvedor com diferentes materiais e foi simulada uma geometria de tubos de sessão quadrada no absorvedor. A simulação apresentou o melhor resultado com um absorvedor construído com 100 tubos de sessão quadrada de polissulfona, no qual a eficiência teoricamente pode chegar a 81,62%. / Efficiency and economy in energy production are key factors in the social and economic development of a country. Solar energy is a source of clean and renewable energy used for heating water through solar collectors. Over the past 15 years, due to the worldwide appeal for the use of more readily recyclable materials and their low cost, flat solar collectors have increasingly used polymeric materials to replace conventional ones. In order to assess which polymeric materials can be used in flat-plate solar collectors, an accelerated temperature test has been conducted on polysulfone (PSU), polyethylene (PE), and polycarbonate (PC). PSU and EP have stood out. PSU had the best result for degradation because its polymeric chain is composed of aromatic rings and strong bonds of carbon, sulfur and oxygen within the backbone of the polymer. Additionally, infrared analyses have been made of the materials aged in the accelerated temperature chamber according to the ATR method or attenuated total reflectance. They presented small molecular chain changes in the spectra in the infrared region as exposure time in the UV chamber increased. Finally, a numerical simulation of a flat solar collector was developed in the ESS (Engineering Equation Solver) platform in which the effect of the number of tubes in the absorber with different materials was simulated as well a geometry of square session tubes in the absorber. The simulation presented the best result with an absorber built with 100 polysulfone square session tubes, in which efficiency can theoretically reach 81.62%.

PERFORMANCE-BASED ANALYSIS OF A REINFORCED CONCRETE SHEAR WALL BUILDING Garrett Richard Hagen In this thesis, a special reinforced concrete shear wall building was designed per ASCE 7-05, and then the performance was investigated using the four analysis procedures outlined in ASCE 41-06. The proposed building was planned as a 6-story office building in San Francisco, CA. The structural system consisted of a two-way flat plate and reinforced concrete columns for gravity loads and slender structural walls for seismic loads. The mathematical building models utilized recommendations from ASCE 41-06 and first-principle mechanics. Moment-curvature analysis and fiber cross-section elements were used in developing the computer models for the nonlinear procedures. The results for the analysis procedures showed that the building met the Basic Safety Objective as defined in ASCE 41-06. The performance levels for the nonlinear procedures showed better building performance than for the linear procedures. This paper addresses previously found data for similar studies which used steel special moment frames, special concentric braced frames, and buckling restrained braced frames for their primary lateral systems. The results showcase expected seismic performance levels for a commercial office building designed in a high seismicity region with varying structural systems and when using different analysis procedures. Keywords: reinforced concrete structural walls, shear walls, performance-based analysis, ETABS, Perform-3D, flat plate, two-way slab.

<p>This thesis investigates the possibility of using an unglazed flat-plate solar collector as a cooling radiator. The solar collector will be connected to the condenser of a heat pump and used as cooler during nighttime. Daytime the solar collector will be connected to the evaporator of the heat pump and used as heat source. The two widely differing fields of application make special demands on the solar collector. The task is given by the heat pump manufacturer Thermia and the main objective is to find out whether a solar collector should be used as a cooler or not. The performance of the solar collector under varying environmental conditions is investigated using COMSOL Multiphysics 3.3. Only the cooling properties are investigated here. The performance of the solar collector as a heat exchanger is estimated using the effectiveness-NTU method, and the solar collector is found to be a good heat exchanger at low wind speeds. The heat transfer coefficients of the convection and radiation are determined for varying temperature and wind speeds. The convective heat transfer coefficient is lowered by tubes above the absorber plate and for a high convective heat transfer rate the solar collector surface should be smooth. For a high radiative heat transfer rate the surface needs to have a high emissivity. The cooling rate is higher from a warm surface than from a cold and since no temperature change of the heat carrier is necessary the solar collector should be kept at a high temperature. To increase the cooling rate alterations need to be made to the solar collector that makes its heating performance deteriorate. A solar collector that can be used for cooling is not an efficient solar collector.</p>