O fígado é um órgão importante para se analisar como o animal reage a agressões químicas. Um dos métodos utlizado para estudar a regeneração hepática é a hepatectomia parcial (HP). Assim, nosso objetivo foi verificar a influência da hepatectomia de 30% e de 70% sobre a taxa de proliferação das células hepática medida pela incorporação de BrdU na região da incisão e no resto do fígado e a proliferação de ductos biliares e de células epiteliais pré-ductulares biliares (CEPDBs) com o uso de uma combinação de 2 anticorpos específicos para citoqueratinas humanas, AE1/AE3. O pico de proliferação nos animais que sofreram HP de 30% do parênquima hepático deu-se após 1 dia da cirurgia enquanto que os animais que sofreram a HP de 70% o pico ocorreu no terceiro dia após a cirurgia.O índice de proliferação foi semelhante para a região próxima ou distante do corte. Para ambas as HP não houve diferença na regeneração do tecido retirado próximo ou distante da área de incisão. Nas regiões distantes da HP havia maior número de ductos havendo o pico do número de ductos coincidindo com o pico de proliferação celular de ambas as HP. Depois da HP o número de CEPDBs cresce consideravelmente. Os pico de proliferação também ocorreram no primeiro e terceiro dia para a HP de 30% e de 70% respectivamente, sendo mais altos na região distante do corte. Assim, durante a regeneração do fígado de C. gariepinus ocorre hiperplasia compensatória por proliferação de hepatócitos, de ductos biliares e de CEPDBs. A hepatectomia de 30% gerou uma resposta regenerativa intensa e é menos traumática para o animal, a região distante do corte reage mais intensamente que a região próxima do corte no que se refere aos ductos biliares e as CEPDBs. / The liver is an important organ in studies aimed to the verification of animals reactions to chemical injuries. The partial hepatectomy (PH) is one of the methods that are usually employed in hepatic regeneration experiments. Our objectives in this work were to verify the influence of 30% and 70% PH on the hepatic cells proliferation index as it is measured by BrdU nuclear uptake in two regions: close to the hepatic surgery region and in a farther region. The biliary ducts and bile preductular epithelial cells (BPDECs) proliferation was quantified with a combination of two antibodies against the human cytokeratins AE1/AE3. The proliferation index peak in 30% hepatectomy animals occurred one day after the surgery, but in 70% hepatectomy animals the peak was only observed after three days from the surgery. Differences between the proliferation index of the close and the far region were not observed and likewise histological differences were absent. In the regions far from the PH site more biliary ducts were counted than in closer regions, but the peaks were coincident in both regions with the hepatocytes proliferation index. It was also observed that the quantity of BPDECs increased. The peaks occurred in the first and third days for the 30% and 70% PH respectively, and both peaks were higher in the region far from the PH site. We may conclude that C. gariepinus liver regeneration after 30% and 70% PH occurs by means of compensatory hyperplasia by hepatocytes, biliary ducts and BPDECs proliferation. The 30% HP stimulated a strong regenerative response and is less traumatic to the animals. The regions far from the PH site reacts more intensely that the close region concerning the stimulation of biliary ducts and BPDECs proliferation.

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Air intake system (AIS) plays an important role on affecting the performance of the engine and the vehicle. The design and optimization of the structures and materials of AIS contributes to producing a quality reliable system, reducing noise, cost and weight at the same time, which are significant to improve the performance of engine and vehicle. Fresh air hoses/pipes are intended to transport, in air cleaner purified, air from the air cleaner to the throttle fitted on the inlet manifold or to the compressor fitted to the exhaust manifold. Air cleaner box is responsible for filtering out the dust and impurities in the air. The charge air pipes are intended to transport purified compressed air from the compressor to the charge air cooler and then to the throttle fitted on the inlet pipe. For the air cleaner box optimization, through the benchmarking and the innovation ideas from the daily life, two alternative optimized designs were introduced to reduce the cost and weight. The first is four clips connectors and the other is spring clamps. For the hose clamps, another innovation design was introduced to replace the previous hose clamps, which is called friction connector on the inner side of the bellow hose, the outer side of the air cleaner box lid and the clean side duct. For the material of the charge air ducts, TPEE was selected to replace the previous EACM rubber hoses. Further tests and prototypes should be conducted and produced to verify the effect of the optimization.

Detached Eddy Simulations (DES) is a hybrid URANS-LES technique that was proposed to obtain computationally feasible solutions of high Reynolds number flows undergoing massive separation with reliable accuracy. Since its inception, DES has been applied to a wide variety of flow fields, but mostly limited to unbounded external aerodynamic flows. This is the first study to apply and validate DES to predict the internal flow and heat transfer in non-canonical flows of industrial relevance. The prediction capabilities of DES in capturing the effects of Coriolis forces, which are induced by rotation, and centrifugal buoyancy forces, which are induced by thermal gradients, are also authenticated. The accurate prediction of turbulent flows is sensitive to the level of turbulence predicted by the turbulence scheme. By treating the regions of interest in LES mode, DES allows the unsteadiness in these regions to develop and hence predicts the turbulence levels accurately. Additionally, this permits DES to capture the effects of system rotation and buoyancy. Computations on a rotating system (a sudden expansion duct) and a system subjected to thermal gradients (cavity with a heated wall) validate the prediction capability of DES. The application of DES is further extended to a non-canonical, internal flow which is of relevance in internal cooling of gas turbine blades. Computations of the fully developed flow and heat transfer shows that DES surpasses several shortcomings of the RANS model on which it is based. DES accurately predicts the primary and secondary flow features, the turbulence characteristics and the heat transfer in stationary ducts and in rotating ducts, where the effects of Coriolis forces and centrifugal buoyancy forces are dominant. DES computations are carried out at a computational cost that is almost an order of magnitude less than the LES with little compromise on the accuracy. However, the capabilities of DES in predicting the transition to turbulence are inadequate, as highlighted by the flow features and the heat transfer in the developing region of the duct. But once the flow becomes fully turbulent, DES predicts the flow physics and shows good quantitative agreement with the experiments and LES. / Ph. D.

Increasing the turbine inlet temperature of gas turbine engines significantly increases their power output and efficiency, but it also increases the likelihood of thermal failure. Internal passages with tiny ribs are typically cast into turbine blades to cool them, and the ability to accurately predict the flow and heat transfer within these channels leads to higher design reliability and prevention of blade failure resulting from local thermal loading. Prediction of the flow through these channels is challenging, however, because the flow is highly turbulent and anisotropic, and the presence of rotational body forces further complicates the flow. Large Eddy Simulations are used to study these flows because of their ability to predict the unsteady flow effects and anisotropic turbulence more reliably than traditional RANS closure models. Calculations in a stationary duct are validated with experiments in the developing flow, fully developed, and 180° bend regions to establish the accuracy and prediction capability of the LES calculations and to aid in understanding the major flow structures encountered in a ribbed duct. It is found that most flow and heat transfer calculations come to within 10-15% of the measurements, typically showing excellent agreement in all comparisons. In the developing flow region, Coriolis effects are found to destabilize turbulence and increase heat transfer along the trailing wall (pressure side), while decreasing leading wall heat transfer by stabilizing turbulence. Coriolis forces improve flow turning in the 180° bend by shifting the shape of the separated recirculation zone at the tip of the dividing wall and increasing the mainstream flow area. In addition, turbulence is attenuated near the leading wall throughout the bend, while Coriolis forces have little effect on trailing wall turbulence in the bend. Introducing and increasing centrifugal buoyancy in the developing flow region increases trailing wall heat transfer monotonically. Along the leading wall, buoyancy increases the size of the recirculation zones, shifting the peak heat transfer to a region upstream of the rib, which decreases heat transfer at low buoyancy parameters but increases it as the buoyancy parameter is increased beyond a value of 0.3. Centrifugal buoyancy in the 180° bend initially decreases the size of the recirculation zone at the tip of the dividing wall, increasing flow area and decreasing flow impingement. At high buoyancy, however, the recirculation zone shifts to the middle of the bend, increasing flow resistance and causing strong flow impingement on the back wall. The Boussinesq approximation is used in the buoyancy calculations, but the accuracy of the approximation comes into question in the presence of large temperature differences. A variable property algorithm is developed to calculate unsteady low speed flows with large density variations resulting from large temperature differences. The algorithm is validated against two test cases: Rayleigh-Bénard convection and Poiseuille-Bénard flow. Finally, design issues in rotating ribbed ducts are considered. The fully developed assumption is discussed with regard to the developing flow region, and controlling the recirculation zone in the 180° bend is considered as a way to determine the blade tip heat transfer and pressure drop across the bend. / Ph. D.

[pt] Trata-se de um estudo sobre métodos de previsão de vida à fadiga de dutos com mossas submetidos a carregamento de pressão interna. Um método é proposto e com ele realiza-se previsões utilizando o método SN, sendo a influência das tensões médias calculadas segundo a parábola de Gerber. Adicionalmente são analisados outros métodos disponíveis na literatura, sendo abordados seus embasamentos teóricos, coeficientes de segurança e validações experimentais. A análise de tensões dos diferentes métodos foi realizada utilizando o Método de Elementos Finitos com o pacote computacional Abaqus 6.10, salvo nos casos em que foram fornecidas equações vindas de regressões de resultados numéricos. Todos os resultados avaliados foram comparados com resultados experimentais disponíveis na literatura, sendo um total de oito curvas avaliadas em seis casos em que se alteraram a espessura do tubo, o diâmetro do punção que gerou a mossa, a pressão inicial e o material do tubo. Os resultados indicam que as diferenças conceituais entre os diferentes métodos se refletem nas previsões geradas e que o método proposto faz previsões próximas aos resultados experimentais, sem o uso de fatores de segurança ou de confiabilidade. / [en] This study aims to analyze different methods to predict the fatigue life in pipelines with dents loaded with internal pressure. A new method is proposed which makes previsions based on the SN method; the mean pressure is taken into account according to the parabola of Gerber. Some other methods available in the literature are analyzed in terms of their safety factors and experimental validation. The stress analysis has been performed for the different methods using Abaqus 6.10, a Finite Element analysis software, except in those cases where a regression curve, based on numerical results, are provided. All the results found have been compared against experimental results available in the literature. A total of eight methods have been evaluated in six cases with different linepipe wall thicknesses, indentor diameters, materials and initial pressures. The results indicate that that different methods produce different life predictions, and the new method presented predict lives with a good match to the experimental data without using safety or reliability factors.