Orientador: Cecília Amélia de Carvalho Zavaglia / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-24T09:00:21Z (GMT). No. of bitstreams: 1 Uebelhart_Beatriz_M.pdf: 3346622 bytes, checksum: f0a455713e558d11ecb3ef1e865148a0 (MD5) Previous issue date: 2013 / Resumo: Uma Bomba de Sangue Centrífuga Implantável (BSCI) está sendo desenvolvida para ser utilizada como assistência circulatória em pacientes com doenças cardiovasculares graves (DCVs). Para algumas doenças cardíacas, a única forma de tratamento é o transplante cardíaco. Um Dispositivo de Assistência Circulatória (DAV) pode ser utilizado para manter a vida do paciente enquanto ele aguarda na fila de espera por um transplante. A BSCI consiste de um DAV e é composta de protótipo, cânulas, motor, controlador, e fonte de energia. A complexidade geométrica de seu rotor dificulta sua construção através de processos de usinagem convencionais. Ao mesmo tempo, o aperfeiçoamento e construção de novos protótipos é essencial, pois permite a realização da análise de seu funcionamento, identificação e correção de falhas. A tecnologia selecionada que permite a construção rápida de um modelo tridimensional de geometria complexa é a prototipagem rápida (PR). Neste trabalho foram utilizados três diferentes tipos de processos de PR no desenvolvimento de protótipos da BCI para realização de testes "In Vitro" e "In Vivo". Os modelos físicos foram construídos através dos processos de Sinterização Seletiva a Laser (SLS), de Modelagem por Fusão e Deposição (FDM) e Estereolitografia (SLA). Através de análises qualitativas selecionou-se um dos processos para confecção dos protótipos da BSCI. Os protótipos foram submetidos a testes "In Vitro" e experimentos "In Vivo". A tecnologia de PR selecionada foi a Estereolitografia. O resultado do teste de desempenho hidrodinâmico apresentou-se satisfatório quando comparado a estudos anteriores. O teste em simulador demonstrou uma melhora nas condições fisiológicas simuladas quando um organismo simulado é submetido a assistência da BCI. Através dos testes "In Vivo" foi possível analisar o comportamento do protótipo e estudar técnicas de implante da BCI, os resultados se apresentaram satisfatórios / Abstract: An Implantable Centrifugal Blood Pump (ICBP) is being developed to be used as circulatory assistance in patients with severe cardiovascular diseases. For certain heart diseases, the only treatment is the heart transplant. A Ventricular Assist Device (VAD) can be used to maintain the patient's life while he waits for a heart transplant. ICBP consists of a VAD and is composed of a prototype, cannulae, motor, controller and energy source. Due the complexity of spiral geometry of the impeller, ICBP prototypes construction is difficult through conventional manufacturing processes. At the same time, the improvements and construction of new prototypes is essential because allows the performance analysis, identification and correction of failures. The chosen technology that allows fast construction of 3D models with complex geometry is Rapid Prototyping (RP). In this study were used three different technologies of RP to develop new ICBP prototypes and perform "In Vitro" and "In Vivo" tests. The physical models were constructed through the processes of Selective Laser Sintering (SLS), Fused and Deposition Modeling (FDM) and Stereolithography (SLA). Through qualitative analysis, between processes, one was selected to construct the ICBP 3D models. "In Vitro" and "In Vivo" tests were performed. SLA rapid prototyping process was selected to construct ICBP models. Hydrodynamic tests results presented satisfactory when compared with previous studies. Cardiovascular Simulator test results presented an improvement in simulated physiological conditions when the organism was submitted to ICBP assistance. Through "In Vivo" tests was possible to analyze the ICBP prototype performance and study ICBP implant techniques, and the results presented satisfactory / Mestrado / Materiais e Processos de Fabricação / Mestra em Engenharia Mecânica

<p>Rising fuel costs and growing environmental concerns have forced gas turbine engine manufacturers to place high value on reducing fuel burn. This trend has pushed compressor technology into new design spaces that are not represented by historical experience. Specifically, centrifugal compressor diffusers are trending toward higher pressure recovery and smaller diameters. The internal fluid dynamics in these new flow regimes are not well understood and additional study is necessary. This work outlines detailed experimental and numerical observations of the flow field through a vaned diffuser for aeroengine applications.</p> <p>The experimental data consist of extensive Laser Doppler velocimetry measurements of the unsteady velocity field from the impeller trailing edge through the majority of the diffuser passage. These data were obtained non-intrusively and yielded all three components of the velocity vector field at approximately 2,000 geometric points. The correlation between fluctuations in the three velocity components were also observed at several key locations to determine the components of the local Reynolds stress tensor.</p> <p>These data indicated a jet/wake profile at the impeller exit represented by a consistent velocity deficit region from hub to shroud adjacent to the suction surface of the passage. This region was more prevalent adjacent to the splitter blade. The unsteady fluctuations due to the propagation of the jet and wake through the diffuser passage persist to 40% downstream of the throat. A complex secondary flow field was also observed with large axial velocities and a passage-spanning vortex developing through the diffuser passage. The velocity data and total-pressure data indicated a region of flow separation developing along the pressure surface of the vane near the hub due to the unsteady propagation of the jet and wake flow through the diffuser. Although this region was stable in time, its development arose due to unsteady aspects of the flow. Finally, the strong interconnection between the jet and wake flow, unsteady fluctuations, secondary velocities, incidence, and flow separation was demonstrated. </p> <p>Computationally, a “best-practice” methodology for the modelling of a centrifugal compressor was developed by a systematic analysis of various turbulence models and many modelling features. The SST and BSL-EARSM turbulence models with the inclusion of fillets, surface roughness, and non-adiabatic walls was determined to yield the best representation of the detailed flow development through the diffuser in steady (mixing-plane) simulations. The accurate modelling of fillets was determined to significantly impact the prediction of flow separation with the SST turbulence closure model. Additionally, the frozen rotor approach was shown to not accurately approximate the influence of unsteady effects on the flow development.</p> <p>Unsteady simulations were also compared to the detailed experimental data through the diffuser. The BSL-EARSM turbulence model best matched the experimentally observed flow field due to the SST model’s prediction of flow separation in the shroud-pressure side corner of the passage. In general, lower levels of axial velocity were predicted numerically that resulted in less spanwise mixing between the endwall and freestream flows. Additionally, the turbulent kinetic energy levels in the computational results showed little streamwise variation through the vaneless and semi-vaneless space. The large variation observed experimentally indicated that the production and dissipation of turbulent kinetic energy through this region was not accurately predicted in the two turbulence models implemented for the unsteady simulations.</p>

This study was conducted to address the controlling factors of biosolids stability as they relate to mesophilic anaerobic digestion, dewatering processes and digestion enhancement by wet sludge disintegration technologies. The working hypothesis of this study is that digestion performance; nuisance odor generation and the degree of digestion enhancement by wet sludge disintegration are directly related to anaerobic floc structure and its interaction with shearing forces. Mesophilic digestion was studied in two modes of operation, convention high rate and internal recycle mode to enhanced digestion using a wet sludge disintegration device. The internal recycle system operated on the premise that stabilized sludge would be removed from the digester disintegrated, either by mechanical shear or ultrasonic disintegration for this study, and returned it for to the digester further for further stabilization. Both benchscale and full-scale demonstrations found this mode of digestion enhancement to be effective for mechanical shear and ultrasonic disintegration. It was also determined that volatile solids destruction in both conventional and enhanced mesophilic anaerobic digesters can be reasonably predicted by the concentration of cations in the sludge being treated. It was found that depending on the disintegration device used to enhance digestion performance was influenced by different cation associated fractions of the sludge floc. Along with the improvement of digester performance, overall biosolids stability was investigated through of volatile organic sulfur emissions from dewatered biosolids. In doing so, a method to mimic high solids centrifugation in the laboratory was developed. The centrifugation method identified three major factors that contribute to the generation of odors from biosolids: shear, polymer dose, and cake dryness. The inclusion of shearings suggest that one means of reducing odors from biosolids generated by centrifugation is to use a shear enhanced digestion technology to degrade odor precursors, such as amino acids, within the digester prior to dewatering. Furthermore, the mechanical shearing within a digester is thought to be similar to that of mechanical shear enhanced digestion; therefore, the floc properties that control the digestion process would control observed odor generation. / Ph. D.

This diploma thesis deals with the phenomenon appearing in hydrodynamic pumps at the sub-optimal flow rate. This phenomenon is inlet recirculation, which is an undesirable phenomenon in the suction of the pump. This recirculation causes cavitation, pressure pulsations and may cause clogging of the suction line. The main goal of the diploma thesis is CFD simulation for the recirculation mode, identification of the flow phenomena, and designs of possible measures to suppress inlet recirculation.

Diplomová práca je zameraná na mikrovlákna na báze biopolyméru poly(3-hydroxybutyrátu) a ich využitie v medicínskych aplikáciách. Teoretická časť práce sa zaoberá štúdiom procesu tvorby vláken pomocou technológie odstredivého zvlákňovania, jeho kinetikou a faktormi ovplyvňujúcimi vznik a vlastnosti vláken. Teoretická časť sa následne orientuje na krátky prehľad biopolymérov používaných v tejto technológii, charakteristiku materiálu poly(3-hydroxybutyrátu) a taktiež prezentuje návrh potenciálnej cieľovej aplikácie daných mikrovláken. Praktická časť sa koncentruje sa prípravu mikrovláken zo spomínaného poly(3-hydroxybutyrátu). Sledované a optimalizované sú viaceré parametre vedúce k lepšej zvlákniteľnosti materiálu. Praktická časť je rozšírená o modifikáciu polymérneho roztoku prídavkom iných biopolymérov a zmäkčovadiel a prípravu mikrovláken z takto modifikovanej polymérnej zmesi. Pozornosť je venovaná taktiež optimalizácii procesných parametrov. Pripravené mikrovlákna sú následne analyzované a charakterizované viacerými metódami a vzájomne porovnávané s cieľom vyvinúť alternatívu k súčasne používaným substrátom pre rast buniek v 3D.

ABSTRACT Photobioreactor Design for Improved Energy Efficiency of Microalgae Production Alexander Burns The objective of this research was to investigate a new photobioreactor (PBR) design for microalgae production that retains the typical advantages of existing tubular PBRs while reducing power consumption by providing simultaneous culture circulation and gas exchange with airlift alone and no centrifugal recirculating pump. Traditional tubular PBR designs feature a compressed air supply and a centrifugal pump for culture circulation and gas exchange. Circulation and gas exchange in a closed-system PBR is necessary to keep the algae suspended and to provide sufficient mass transfer (mainly for the exchange of oxygen and carbon dioxide). In a traditional tubular PBR sparged air keeps the culture well mixed and strips out excess dissolved oxygen in an airlift-column unit, while the centrifugal pump circulates the culture in the tubular stage and decreases the amount of air bubbles traveling into this stage; where most of the photosynthesis occurs. The PBR design proposed herein does away with the usual centrifugal pump. The air blower performs both gas exchange in the airlift columns and system-wide circulation. This builds on a previous tubular PBR design that provides circulation and gas exchange by airlift alone, which was patented by Cathcart in 2011. However, the Cathcart patent does not provide data on mixing, gas exchange, energy consumption, flow regime or biomass productivity. The new design described here builds on the Cathcart design, but includes several unique design features, such as larger diffuser columns which provide airlift-induced flow for a series of vertical PBR tubes. To perform a power consumption v analysis, a pilot-scale prototype of the new PBR design was built and operated. The prototype PBR consisted of two airlift columns attached to 9 m of vertical serpentine tubing connected to the top and bottom by standard 90-degree PVC elbows in a U-bend fashion to each column to make a total working volume of 235 L. The airlift columns were about 1.5 m tall and 30.5 cm ID, while the serpentine tubes were about 0.9 m tall and 7.6 cm ID to make a total of five vertical tubes for every airlift column. Data collected for this prototype design suggest an average overall areal productivity (OAP) of 111 g m-2 d-1 (g biomass m-2 total land area with empty space day-1), an average illuminated surface productivity (ISP) of 14.3 g m-2 d-1 (g biomass m-2 reactor photo-stage day-1), an average volumetric productivity (VP) of 0.55 g L-1 d-1 (g biomass L-1 reactor working volume day-1), a specific power input in the range of 330 to 360 W m-3 (W power needed for culture circulation and gas exchange m-3 reactor working volume) and a specific biomass productivity (SBP) in the range of 17.6 to 19.1 mg kJ-1 (mg biomass kJ-1 energy needed for culture circulation and gas exchange) with Chlorella vulgaris as the model algae. The biomass productivity per energy input (SBP) of the new PBR design appears to be higher than that of similar designs currently described in the literature. Elimination of the centrifugal pump in a tubular PBR design is a concept worth further study for potential energy savings.

This thesis includes the theoretical part explaining problematic of centrifugal pumps, Y(Q) characteristics of these centrifugal pumps and stability of these characteristics, ways and conditions for stabilisation and adaptations heading to stabilisation.

The master thesis deals with design for casting mould of an impeller wheel for investment casting lost wax and machining technology with utilization CAD software SolidWorks 2008 and CAM software PowerMill 9. Subsequent verification of machining on vertical machining center MCV 1210. At the end, techno-economic evaluation is done.

This master's thesis includes theoretical analysis of characteristics of a centrifugal pump, conditions of stability of Y(Q) characteristic, calculation of characteristics ßč(ns), modifications leading to stabilization of a spiral body and a runner, a design of the spiral, the runner and follow-up computation in Fluent program.

The master's thesis deals with compressor turbochargers used for supercharging of combustion engines. The aim of the thesis is feasibility study of compressor surge limit simulation. First of all the principle and purpose of supercharged combustion engines is described and the compressors' types using for supercharging are mentioned as well. The main part of the thesis is focused on flow instabilities and their influence on compressor operating zone. There are mentioned some possibilities of operating zone extension. The practical part comprises the simplified computation of a one stage of centrifugal compressor and flow analysis by means of CFD simulation.