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Submitted by ANA CARULINA REZENDE DE MORAES FERREIRA null (caru_moraes@hotmail.com) on 2017-05-04T16:53:13Z No. of bitstreams: 1 Dissertação Medpore final para impressao final.pdf: 4130459 bytes, checksum: b6913d1ec874d832fc81b851779f2184 (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-05-05T13:25:58Z (GMT) No. of bitstreams: 1 ferreira_acrm_me_araca.pdf: 4130459 bytes, checksum: b6913d1ec874d832fc81b851779f2184 (MD5) / Made available in DSpace on 2017-05-05T13:25:58Z (GMT). No. of bitstreams: 1 ferreira_acrm_me_araca.pdf: 4130459 bytes, checksum: b6913d1ec874d832fc81b851779f2184 (MD5) Previous issue date: 2017-03-08 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Entre os materiais aloplásticos, o Medpor® apresentou um aumento consideravel no uso de 17% a 30%, portanto o objetivo desse trabalho foi avaliar a utilização do Medpor® na reconstrução do assoalho orbitário. Foram utilizados 18 ratos que sofreram trauma cirúrgico no assoalho orbitário, simulando uma fratura tipo "blow-out". O lado direito do animal recebeu implante de Medpor® e o lado esquerdo não recebeu qualquer tipo de material. Nos períodos de 15, 40 e 90 dias foram realizadas as eutanásias e obtenção das peças para processamento histológico e imunohistoquímico. Os cortes obtidos foram corados com hematoxilina e eosina, tricrômico de Masson e marcação imunohistoquímica nos períodos de 15, 40 e 90 dias com a osteocalcina e RUNX2. O processo de reparo no lado controle finalizou com neoformação óssea aos 40 dias e perda do contorno ósseo inicial, criando um defeito no assoalho de órbita. O grupo tratado mostrou prevalência de tecido conjuntivo em contato com o implante de Medpor®, tanto em sua periferia quanto no seu interior. Não houve processo inflamatório intenso e ou agudo junto ao material. A imunomarcação mostrou escores intensos de OC após 15 dias de pós- operatórios e manteve expressão moderada após 40 e 90 dias pós-operatório, a RUNX2 foi moderadamente expressa em todos os períodos avaliados. Concluimos que o polietileno poroso (Medpor®) é um biomaterial bionert seguro e eficaz, a sua presença levou ao reparo ósseo local e compensou a ausência de tecido ósseo na sustentação do globo ocular. / The aim of this research was to assessed histological and immunohistochemi cal properties in the use of porous polyethylene (Medpor®) for orbital floor reconstruction. Under general anesthesia 18 male rats (Rattus, norvegicus, albinus, Wistar) underwent bilateral surgical defect, simulating blowout fracture and infraorbital rim. Groups were divided as follow: GI control group and GII surgical defects were reconstructed with Medpor®. After 15, 40, and 90 days animals were euthanized with anesthetic overdose. Orbital specimens were laboratorial process, coronal slices were stained in Hematoxylin and Eosin and Masson trichrome. Immunohistochemical assess of osteocalcin (OC) and Corebinding factor alpha1 (Cbfa1) were performed. Bone repair at the control group was achieved after 40 days with loss of the orbital rim and lack of ocular support. Immunolabeling showed intense scores of OC after 15 days post-operative and maintain moderate expression after 40 and 90 days postoperative, Cbfa1 was moderately express within all the periods evaluated. Medpor® group showed fibrous tissue in contact with the implant in the inner and outer surface, without newbone formation and without intense inflammatory infiltrate nearby the biomaterial, the Medpor® gave enough support for the ocularglobe.

Improvements to heritage gas turbine engines will be needed in the coming years as the demand made on these systems increase. While industry continually presses for higher performance of both military and civilian aero engines, the government simultaneously raises the bar for emissions standards in the commercial sector to support public health. The next generation of aerospace gas turbine engines will be defined by their ability to operate at high power conditions while maintaining efficiency. This challenge is compounded by airlines' proposition of a return to supersonic flight- an operating regime characterized by higher total temperatures, and thus more NOx production. Lean Direct Injection (LDI) is a combustion scheme that was proposed by NASA, and inherently addresses the needs of both the private sector and the military. LDI is a liquid fueled combustor that promotes rapid mixing of fuel and air at the entrance of the combustor. Despite the benefits of LDI, it has never been implemented, nor has any other lean burning scheme been implemented in an aircraft due to the system level complications of such technology. This dissertation focuses on the dynamics of thermoacoustic instability and lean blowout (LBO), two of the major complications that industry will face when they attempt to incorporate LDI in a production engine. The present dissertation investigates these dynamics from a fundamental and applications standpoint. Fundamental insights on thermoacoustic instabilities are developed by investigating droplet dynamics in a self-excited flow field, and significant oscillations in droplet diameters are discerned. PDPA measurement will be taken to identify coupling of the fuel spray with the instability, and a phase locking algorithm will be used to develop a new spray parameter than is more indicative of combustion heat release that the standard Sauter mean diameter. Next, while varying the swirl number and the venturi geometry of the combustor, the evolution of the flow field will be characterized. An in-house innovation called the Direct Rotation Swirler (DRS) is built for this purpose. The DRS uses an active geometry to provide continuously variable swirl number modulation. The effects of these changes on lean blow out, pressure drop and NOx emissions will then be experimentally determined. Venturis were rapidly manufactured using a ii casting procedure that was developed to make venturi geometries from a commercially available ceramic at very low cost. / Doctor of Philosophy / Improvements to heritage gas turbine engines will be needed in the coming years as the demand made on these systems increase. While industry continually presses for higher performance of both military and civilian aero engines, the government simultaneously raises the bar for emissions standards in the commercial sector to support public health. The next generation of aerospace gas turbine engines will be defined by their ability to operate at high power conditions while maintaining efficiency. This challenge in compounded by airlines' proposition of a return to supersonic flight- an operating regime characterized by higher total temperatures, and thus more NOx production. Lean Direct Injection (LDI) is a combustion scheme that was proposed by NASA, and inherently addresses the needs of both the private sector and the military. LDI is a liquid fueled combustor that promotes rapid mixing of fuel and air at the entrance of the combustor. Rapid mixing yields a clean, even flame and eliminates the fuel-rich primary zone which is the heart of NOx production. Despite the benefits of LDI, it has never been implemented, nor has any other lean burning scheme been implemented in an aircraft due to the system level complications of such technology. This dissertation focuses on two of the major complications that industry will face when they attempt to incorporate LDI in a production engine. Drastically reducing the local hot spots in the primary zone is fundamentally necessary to improve pattern factor and emissions, but this change is directly at odds with two dynamic phenomenon that plague combustors. These effects are thermoacoustic instabilities, and lean blow out. Thermoacoustic instabilities are a major concern in any type of combustor and instabilities are more common and more intense in lean engines which is a significant safety risk to aircraft. A thermoacoustic instability occurs when pressure waves in an engine grow to high amplitudes. Small pressure waves are normal in any combustion process, but when the acoustic waves couple with the heat release, the waves can grow uncontrollably. The amplitudes can reach magnitudes capable of damaging the combustor or significantly reducing its cyclic life. Due to the high iv standard of safety in the aerospace industry, lean combustion will not be implemented until engines can be designed to avoid instabilities throughout the entire flight envelope. Lean blow out occurs when the fuel to air ratio of the engine becomes too low to sustain a flame. Lean blow out is a transient phenomenon that is dependent on local flame speeds, local chemical time scales and turbulence parameters. Typically, lean blow out is combated by designing a rich flame anchoring region that burns with plenty of excess fuel so that even if the fuel flow rate is reduced, a core region is still within its flammability regions. The present dissertation investigates these dynamics from a fundamental and applications standpoint. Fundamental insights on thermoacoustic instabilities are developed by investigating droplet dynamics in a self-excited flow field, and significant oscillations in droplet diameters are discerned. PDPA measurement will be taken to identify coupling of the fuel spray with the instability, and a phase locking algorithm will be used to develop a new spray parameter than is more indicative of combustion heat release that the standard Sauter mean diameter. Next, while varying the swirl number and the venturi geometry of the combustor, the evolution of the flow field will be characterized. An in-house innovation called the Direct Rotation Swirler (DRS) is built for this purpose. The DRS uses an active geometry to provide continuously variable swirl number modulation. The effects of these changes on lean blow out, pressure drop and NOx emissions will then be experimentally determined. Venturis were rapidly manufactured using a casting procedure that was developed to make venturi geometries from a commercially available ceramic at very low cost.

An unsteady, finite-rate, one-dimensional model has been developed for the analysis for gas-turbine combustors. The basis of the model is the one-dimensional, integral form of the conservation equations for multi-species, non-equilibrium, reacting mixtures. Special procedures were devised for the flow-division of the inlet flow into primary- and annular-flows, for both straight- and reverse-flow combustors. This allows the model to handle complete combustor configurations, which at present are beyond the reach of more sophisticated CFD tools. The model was validated with a steady-state analytical solution for a basic problem, and with steady-state results from a production code applied to a production combustor. Additional calculations show the ability of the code to predict blow-out due to rich and lean mixtures, and to predict the response of a combustor to perturbations in operating and boundary conditions. / Ph. D.

No description available.

Oil well blow outs are investigated to determine methods to quickly and accurately respond to an emergency situation. Flow rate is needed to guide containment and dispersal operations. The Stratified Integral Multiphase Plume, SIMP, model was used to investigate the range of initial conditions available to integral modeling. Sensitivity to initial conditions is modest, but without experimental data at the appropriate scale the most accurate condition is unable to be determined. Flow rates are difficult to directly measure in blow out situations, so another method must be determined; therefore, sensitivity of several parameters to flow rate was also evaluated. Methane concentration in the first intrusion can be used in conjunction with velocity and trap height measurements to determine flow rate using an integral model. Plume width and temperature were determined to have little sensitivity. Separately, a containment dome was tested in the laboratory to determine if a full scale dome can be used to contain an oil leak in the field. The dome was found to have satisfactory entrapment in the designed position.

NOx sensors have become salient components in the development of efficient exhaust after treatment system for heavy duty vehicles in the past few years. When the accumulated water inside the silencer splashes on to the NOx sensor, it can cause permanent cracks in the sensor. To protect the sensor from this mode of failure, a dew point strategy is developed at Scania. This is important to predict when it is safe to switch on the NOx sensor without causing any harm to it. But the strategy currently includes only the phase transfer phenomena and neglects the effect of the water blow out phenomena inside the silencer. To investigate the effect of water blow out, an experimental test method is designed and the experiments are conducted at different locations in the silencer. The results from the experiments shows that the effect of water blow out is certainly an important factor to develop a better dew point strategy model. For a selected location, the quantity of water remaining after blow out and the time taken for the blow out phase are collected as data from the experiments. A mathematical model for the water blow out phenomena is developed in MATLAB. The model estimates the maximum amount of water which could be present in all the subvolumes of the silencer considering the effect of water blow out. The model is verified with the experimental data for a Scania CAS1 silencer. Calibration guidelines for the developed blow out model are also documented in this report. / NOx sensorer har blivit viktiga komponenter i utvecklingen av ett effektivt avgassystem för tunga fordon under de senaste åren. När det ackumulerade vattnet i ljuddämparen stänker på NOx-sensorn kan det orsaka permanenta sprickor i sensorn. För att skydda sensorn från detta misslyckande utvecklas en daggpunktsstrategi på Scania. Detta är viktigt att förutsäga när det är säkert att slå på NOx-sensorn utan att skada den. Men strategin innehåller för närvarande endast fasöverföringsfenomenen och försummar effekten av att vatten blåser ut fenomen inuti ljuddämparen. För att undersöka effekten av utblåsning av vatten utformas en experimentell testmetod och experimenten utförs på olika platser i ljuddämparen. Resultaten från experimenten visar att effekten av vattenblåsning verkligen är en viktig faktor för att utveckla en bättre daggpunktsstrategimodell. För en vald plats samlas mängden vatten kvar efter utblåsning och den tid det tar för utblåsningsfasen som data från experimenten. En matematisk modell för fenomen för vattenblåsning utvecklas i MATLAB. Modellen uppskattar den maximala mängden vatten som kan finnas i ljuddämparens undervolymer med tanke på effekten av vatten som blåser ut. Modellen verifieras med experimentdata för en Scania CAS1 ljuddämpare. Kalibreringsriktlinjer för den utvecklade utblåsningsmodellen dokumenteras också i denna rapport.