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Design and Analysis of a Toroidal Jet-Stirred Reactor for Ammonia-Hydrogen Jet Engine DevelopmentZamora, David S 01 January 2024 (has links) (PDF)
Mixtures of ammonia and hydrogen have received significant interest recently as a possible replacement for hydrocarbon fuels. A toroidal jet-stirred reactor (TJSR) was designed and constructed to combust these mixtures in the well-stirred limit for validating chemical kinetic mechanisms and improving the current understanding of the combustion properties of this fuel. The TJSR was designed to achieve low residence times – on the order of 5 ms – to approximate the conditions in an aircraft gas turbine combustor. Simulations were conducted to determine mass flow rates, expected emissions output, and expected lean blow out. Based on these results, material studies were conducted to determine the best materials for each of the TJSR's components. Thermomechanical were conducted to determine the expected temperature distribution and thermal expansion during operation. Casing components were designed to seal the gases in the reactor as well as provide means to connect it to a pressure vessel or other piping. This work will allow for chemical mechanism validation of lean blowout in ammonia-hydrogen mixtures while laying the foundation for future high-pressure testing of such mixtures up to 60 bar.
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[en] STUDY OF RELIEF WELLS TO KILL A BLOWOUT IN A SUBSEA GAS WELL / [pt] ESTUDO SOBRE POÇOS DE ALÍVIO PARA CONTROLE DE BLOWOUT EM POÇO MARÍTIMO DE GÁSFABRICIO GONCALVES AZEVEDO 24 October 2017 (has links)
[pt] Acidentes com influxo descontrolado de hidrocarbonetos em um poço de petróleo (blowouts) são eventos com baixa probabilidade de ocorrência na indústria, porém têm impactos catastróficos. O evento de
Macondo, com uma sonda afretada pela British Petroleum (BP) no Golfo do México (GoM), mostrou que um acidente dessa proporção tem um impacto significativo nas pessoas, no meio ambiente, nos ativos e na
imagem da empresa. Portanto, uma resposta rápida e definitiva para o problema se mostra necessária. Dentre as possibilidades de se conter um derramamento de óleo ocasionado por um blowout, a mais efetiva para cessar o vazamento com segurança e abandonar definitivamente o poço em descontrole é o poço de alívio. Trata-se de um poço direcional perfurado a uma determinada distância do poço em blowout, respeitando-se critérios mínimos de segurança, com o objetivo de interceptar este no ponto estabelecido em projeto. Após a interceptação, injeta-se fluido de alta densidade que, quando preenche o poço que estava em blowout, gera uma contra-pressão capaz de cessar o influxo de hidrocarbonetos do
reservatório. Quando é feita essa contra-pressão e o poço que estava em blowout estiver estável e sem influxo, injeta-se cimento pelo poço de alívio para que seja tamponado o reservatório e o poço possa ser abandonado de forma definitiva. No presente trabalho o enfoque é no amortecimento do poço em blowout através do poço de alívio e, portanto, parte-se do pressuposto que a detecção e interceptação do poço em influxo foi feita com sucesso no ponto desejado. A detecção, a interceptação e o abandono no poço em blowout não são estudados com detalhes. O trabalho é desenvolvido tomando como base um poço exploratório de gás a ser simulado, trabalhando os requisitos de pressão e vazão que melhor se adequam ao proposto. O objetivo do amortecimento do poço em blowout pelo poço de alívio é cessar o influxo descontrolado de forma eficaz, otimizando os parâmetros de pressão, vazão e volume de fluido às
capacidades de sondas e embarcações disponíveis no mercado. Caso não seja possível o amortecimento variando a densidade do fluido injetado e a pressão nas bombas de injeção, parte-se para mudanças na
estratégia de amortecimento como, por exemplo, variação no número de poços de alívio a serem perfurados para amortecer o poço em blowout ao mesmo tempo. Não será objetivo do presente trabalho a modificação no projeto do poço com o objetivo de facilitar o amortecimento. / [en] Accidents with uncontrolled influx of hydrocarbons into an oil well (blowouts) are events with a low probability of occurrence in the industry. Although, if they occur, the impact may be catastrophic. The Macondo event, with British Petroleum s rig (BP) in the Gulf of Mexico (GoM), showed that an accident of this proportion has a significant impact on people, environment and an image of the company. Therefore, a quick and definitive response for the problem is necessary. There are several possibilities to contain an oil spill caused by a blowout. However, the most effective way to safely plug and abandon (P and A) the blowout well is the relief well. This technique consists of the construction of a directional well at a certain distance from the blowout well, respecting minimum safety criteria, in order to intercept this at the point established in the project. After the interception, kill mud is pumped at high rates what makes a
backpressure capable of killing the blowout well. When this backpressure is enough to kill the blowout well, cement is pumped through the relief well to plug and abandon permanently the well. In the present work, the objective is to kill the blowout well and we consider that detection and interception of the blowout well was successfully been made at the target point. Detection, interception and P and A of the blowout well are not covered in detail. This work is developed based on an exploratory gas well to be simulated, working the pump rate and pump pressure requirements that best fit in the proposed one. The purpose of well killing is to kill the well optimizing the parameters of pressure, flow and volume of fluid considering the rig and vessels available in the market. If well killing is not possible by varying the density of the kill mud and pump pressure it will be tried new strategies like changing the number of relief wells at the same time to be drilled killing the blowout well. It s not a purpose of this study to change the well design.
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[en] A STUDY ON BLOWOUT CONTROL VIA RELIEF WELL: INCREASING DRILLSHIP CAPACITY / [pt] ESTUDO SOBRE AMORTECIMENTO DE POÇO EM BLOWOUT VIA POÇO DE ALÍVIO: AUMENTO DA CAPACIDADE DAS SONDASELIZA GALVAO DA SILVA CARDOSO 02 September 2024 (has links)
[pt] A energia desempenha um papel estratégico global, com a indústria do
petróleo sendo uma fonte crucial. No entanto, iniciativas visando reduzir a
dependência do petróleo surgem, impulsionadas principalmente por preocupações
ambientais, como as mudanças climáticas. A transição energética ganha destaque
nas agendas nacionais, refletindo a interligação entre energia e meio ambiente.
Apesar da redução na previsão de crescimento da demanda a indústria global de
petróleo e gás, a indústria do petróleo permanece vital, sustentando fontes de
energia, gerando receitas e empregos. Contudo, a indústria enfrenta pressões
ambientais crescentes, destacando a necessidade de investir continuamente em
segurança nas operações de exploração de poços. O blowout, apesar de ser evento
com baixa probabilidade de ocorrência, representa uma ameaça grave, não apenas
para a imagem da empresa, mas também para o meio ambiente e a vida das pessoas.
O exemplo do blowout de Macondo, ocorrido no Golfo do Mexico, em operação da
British Petroleum (BP) evidencia os impactos significativos. O combate ao blowout
envolve mitigação de impacto e controle da fonte. Estratégias essenciais para
mitigação de impactos e o controle da fonte incluem o fechamento do poço com
equipamento de bloqueio (capping) e a construção de um poço de alívio. O primeiro
é uma ação rápida para fechar o poço e cessar o vazamento de hidrocarboneto para
o meio ambiente, enquanto o segundo visa construir um poço adicional para
interceptar, amortecer e abandonar de forma definitiva o poço em blowout. O
presente trabalho concentra-se em apresentar soluções para amortecimento do poço
em blowout via poço de alívio em situações que exigem altas vazões e volumes.
Simulações revelam desafios técnicos, como demandas de grandes volumes e altas
vazões de amortecimento. Portanto, a pesquisa busca oferecer soluções
diferenciadas para atender a essas demandas específicas e contribuir para a
segurança e eficácia das operações. / [en] Energy plays a global strategic role, with the oil industry being a crucial
source. However, initiatives aimed at reducing dependence on oil are emerging,
mainly driven by environmental concerns such as climate change. Energy transition
gains prominence in national agendas, reflecting the interconnectedness between
energy and the environment. Despite the reduction in the demand growth forecast,
the global oil and gas industry, the oil industry remains vital, sustaining energy
sources, generating revenue, and jobs. However, the industry faces increasing
environmental pressures, highlighting the need for continuous investment in safety
in well drilling operations. Blowouts, although events with low probability of
occurrence, represent a serious threat not only to the company s image but also to
the environment and people s lives. The example of the Macondo blowout in the
Gulf of Mexico, during British Petroleum (BP) operation, illustrates significant
impacts. Combatting blowouts involves impact mitigation and source control.
Essential strategies for impact mitigation and source control include well capping
and the construction of a relief well. The former is a rapid action to close the well
and stop hydrocarbon leakage into the environment, while the latter aims to build
an additional well to intercept, killing, and permanently abandon the blowout well.
This work focuses on presenting solutions for blowout well killing via relief well
in situations requiring high flow rates and volumes. Simulations reveal technical
challenges, such as demands for large volumes and high pump rates. Therefore, the
research seeks to offer differentiated solutions to meet these specific demands and
contribute to the safety and effectiveness of operations.
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Improved regulatory oversight using real-time data monitoring technologies in the wake of MacondoCarter, Kyle Michael 10 October 2014 (has links)
As shown by the Macondo blowout, a deepwater well control event can result in loss of life, harm to the environment, and significant damage to company and industry reputation. Consistent adherence to safety regulations is a recurring issue in deepwater well construction. The two federal entities responsible for offshore U.S. safety regulation are the Department of the Interior’s Bureau of Safety and Environmental Enforcement (BSEE) and the U.S. Coast Guard (USCG), with regulatory authorities that span well planning, drilling, completions, emergency evacuation, environmental response, etc. With such a wide range of rules these agencies are responsible for, safety compliance cannot be comprehensively verified with the current infrequency of on-site inspections. Offshore regulation and operational safety could be greatly improved through continuous remote real-time data monitoring. Many government agencies have adopted monitoring regimes dependent on real-time data for improved oversight (e.g. NASA Mission Control, USGS Earthquake Early Warning System, USCG Vessel Traffic Services, etc.). Appropriately, real-time data monitoring was either re-developed or introduced in the wake of catastrophic events within those sectors (e.g. Challenger, tsunamis, Exxon Valdez, etc.). Over recent decades, oil and gas operators have developed Real-Time Operations Centers (RTOCs) for continuous, pro-active operations oversight and remote interaction with on-site personnel. Commonly seen as collaborative hubs, RTOCs provide a central conduit for shared knowledge, experience, and improved decision-making, thus optimizing performance, reducing operational risk, and improving safety. In particular, RTOCs have been useful in identifying and mitigating potential well construction incidents that could have resulted in significant non-productive time and trouble cost. In this thesis, a comprehensive set of recommendations is made to BSEE and USCG to expand and improve their regulatory oversight activities through remote real-time data monitoring and application of emerging real-time technologies that aid in data acquisition and performance optimization for improved safety. Data sets and tools necessary for regulators to effectively monitor and regulate deepwater operations (Gulf of Mexico, Arctic, etc.) on a continuous basis are identified. Data from actual GOM field cases are used to support the recommendations. In addition, the case is made for the regulator to build a collaborative foundation with deepwater operators, academia and other stakeholders, through the employment of state-of-the-art knowledge management tools and techniques. This will allow the regulator to do “more with less”, in order to address the fast pace of activity expansion and technology adoption in deepwater well construction, while maximizing corporate knowledge and retention. Knowledge management provides a connection that can foster a truly collaborative relationship between regulators, industry, and non-governmental organizations with a common goal of safety assurance and without confusing lines of authority or responsibility. This solves several key issues for regulators with respect to having access to experience and technical know-how, by leveraging industry experts who would not normally have been inaccessible. On implementation of the proposed real-time and knowledge management technologies and workflows, a phased approach is advocated to be carried out under the auspices of the Center for Offshore Safety (COS) and/or the Offshore Energy Safety Institute (OESI). Academia can play an important role, particularly in early phases of the program, as a neutral playing ground where tools, techniques and workflows can be tried and tested before wider adoption takes place. / text
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Mechanisms of Lean Flame ExtinctionLasky, Ian M 01 January 2018 (has links) (PDF)
Lean flame blowout is investigated experimentally within a high-speed combustor to analyze the temporal extinction dynamics of turbulent premixed bluff body stabilized flames. The lean blowout process is induced through fuel flow reduction and captured temporally using simultaneous high-speed particle imaging velocimetry (PIV) and CH* chemiluminescence. The evolution of the flame structure, flow field, and the resulting strain rate along the flame are analyzed throughout extinction to distinguish the physical mechanisms of blowout. Flame-vortex dynamics are found to be the main driving mechanism of flame extinction; namely, a reduction of flame-generated vorticity coupled with an increase of downstream shear layer vorticity. The vorticity dynamics are linked to hydrodynamic instabilities that vary as a function of the decreasing equivalence ratio. Frequency analysis is performed to characterize the dynamical changes of the hydrodynamic instability modes during flame extinction. Additionally, various bluff body inflow velocity regimes are investigated to further characterize the extinction instability modes. Both equivalence ratio and flow-driven instabilities are captured through a universal definition of the Strouhal number for the reacting bluff body flow. Finally, a Karlovitz number-based criterion is developed to consistently predict the onset of global extinction for different inflow velocity regimes.
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NON-REACTING SPRAY CHARACTERISTICS OF ALTERNATIVE AVIATION FUELS AT GAS TURBINE ENGINE CONDITIONSDongyun Shin (10297850) 06 April 2021 (has links)
<div>The aviation industry is continuously growing amid tight restrictions on global emission</div><div>reductions. Alternative aviation fuels have gained attention and developed to replace the</div><div>conventional petroleum-derived aviation fuels. The replacement of conventional fuels with</div><div>alternative fuels, which are composed solely of hydrocarbons (non-petroleum), can mitigate</div><div>impacts on the environment and diversify the energy supply, potentially reducing fuel costs.</div><div>To ensure the performance of alternative fuels, extensive laboratory and full-scale engine</div><div>testings are required, thereby a lengthy and expensive process. The National Jet Fuel Combustion</div><div>Program (NJFCP) proposed a plan to reduce this certification process time and</div><div>the cost dramatically by implementing a computational model in the process, which can be</div><div>replaced with some of the testings. This requires an understanding of the influence of chemical/</div><div>physical properties of alternative fuels on combustion performance. The main objective</div><div>of this work is to investigate the spray characteristics of alternative aviation fuels compared</div><div>to that of conventional aviation fuels, which have been characterized by different physical</div><div>liquid properties at different gas turbine-relevant conditions.</div><div>The experimental work focuses on the spray characteristics of standard and alternative</div><div>aviation fuels at three operating conditions such as near lean blowout (LBO), cold engine</div><div>start, and high ambient pressure conditions. The spray generated by a hybrid pressureswirl</div><div>airblast atomizer was investigated by measuring the drop size and drop velocity at</div><div>a different axial distance downstream of the injector using a phase Doppler anemometry</div><div>(PDA) measurement system. This provided an approximate trajectory of the largest droplet</div><div>as it traveled down from the injector. At LBO conditions, the trend of decreasing drop size</div><div>and increasing drop velocity with an increase in gas pressure drop was observed for both</div><div>conventional (A-2) and alternative aviation fuels (C-1, C-5, C-7, and C-8), while the effect of</div><div>fuel injection pressure on the mean drop size and drop velocity was observed to be limited.</div><div>Moreover, the high-speed shadowgraph images were also taken to investigate the effect of</div><div>the pressure drop and fuel injection pressures on the cone angles. Their effects were found</div><div>to be limited on the cone angle.</div><div><div>The spray characteristics of standard (A-2 and A-3) and alternative (C-3) fuels were</div><div>investigated at engine cold-start conditions. At such a crucial condition, sufficient atomization</div><div>needs to be maintained to operate the engine properly. The effect of fuel properties,</div><div>especially the viscosity, was investigated on spray drop size and drop velocity using both</div><div>conventional and alternative aviation fuels. The effect of fuel viscosity was found to be minimal</div><div>and dominated by the effect of the surface tension, even though it showed a weak trend</div><div>of increasing drop size with increasing surface tension. The higher swirler pressure drop</div><div>reduced the drop size and increased drop velocity due to greater inertial force of the gas for</div><div>both conventional and alternative aviation fuels at the cold start condition. However, the</div><div>effect of pressure drop was observed to be reduced at cold start condition compared to the</div><div>results from the LBO condition.</div><div>The final aspect of experimental work focuses on the effect of ambient pressures on the</div><div>spray characteristics for both conventional (A-2) and alternative (C-5) aviation fuels. Advanced</div><div>aviation technology, especially in turbomachinery, has resulted in a greater pressure</div><div>ratio in the compressor; therefore, greater pressure in combustors for better thermal efficiency.</div><div>The effect of ambient pressure on drop size, drop velocity, and spray cone angle was</div><div>investigated using the PDA system and simultaneous Planar Laser-Induced Fluorescence</div><div>(PLIF) and Mie scattering measurement. A significant reduction in mean drop size was</div><div>observed with increasing ambient pressure, up to 5 bar. However, the reduction in the mean</div><div>drop size was found to be limited with a further increase in the ambient pressure. The effect</div><div>of the pressure drop across the swirler was observed to be significant at ambient pressure of</div><div>5 bar. The spray cone angle estimation at near the swirler exit and at 25.4 mm downstream</div><div>from the swirler exit plane using instantaneous Mie images was found to be independent of</div><div>ambient pressure. However, the cone angle at measurement plane of 18 mm in the spray</div><div>was observed to increase with increasing ambient pressure due to entrainment of smaller</div><div>droplets at higher ambient pressure. Furthermore, the fuel droplet and vapor distribution in</div><div>the spray were imaged and identified by comparing instantaneous PLIF and Mie images.</div><div>Lastly, a semi-empirical model was also developed using a phenomenological three-step</div><div>approach for the atomization process of the hybrid pressure-swirl airblast atomizer. This</div><div>model includes three sub-models: pressure-swirl spray droplet formation, droplet impingement, and film formation, and aerodynamic breakup. The model predicted drop sizes as a</div><div>function of ALR, atomizing gas velocity, surface tension, density, and ligament length and</div><div>diameter and successfully demonstrated the drop size trend observed with fuel viscosity,</div><div>surface tension, pressure drop, and ambient pressure. The model provided insights into the</div><div>effect of fuel properties and engine operating parameters on the drop size. More experimental</div><div>work is required to validate the model over a wider range of operating conditions and</div><div>physical fuel properties.</div><div>Overall, this work provides valuable information to increase understanding of the spray</div><div>characteristics of conventional and alternative aviation fuels at various engine operating</div><div>conditions. This work can provide valuable data for developing an advanced computational</div><div>combustor model, ultimately expediting the certification of new alternative aviation fuels.</div></div>
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Experiments with a High Pressure Well Stirred ReactorGross, Justin Tyler January 2014 (has links)
No description available.
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Assessment Of Forensic And Clinical Criteria Of Orbital Blowout Fractures For Use In Bioarchaeological AnalysisOrnot, Dylan E 01 January 2024 (has links) (PDF)
Orbital blowout fractures are a particular facial fracture occurring within the inner eye orbits of the face caused by blunt force trauma to the eyeball or the lower orbital rim. This fracture is common in modern clinical contexts due to physical assaults, but examining this fracture in skeletal material can also provide insights into the patterns of interpersonal violence within the fields of bioarchaeology and forensic anthropology. Issues with analyzing this fracture in skeletal material arise due to the clinical assessment practices of blowout fractures, where medical practitioners are highly focused on the soft tissue presentations of the fracture in a patient. In this study, standard clinical criteria for defining an orbital blowout fracture were analyzed and translated into criteria that could be used to assess skeletal material where no soft tissue is present. A set of scoring criteria was developed to analyze skeletal material based on four traits commonly observed in this fracture pattern, and the material was examined for any post-mortem taphonomy that could be mistaken for perimortem trauma. In this study, thirteen individuals were selected from online osteological databases and examined to score the possible presence of orbital blowout fractures. The scoring results of this study were further tested using positive and negative likelihood ratio tests (LRT) and indicated that eight individuals were highly likely to have blowout fractures present. The presence of nasal fractures was noted in 69.2% of individuals utilized in this study and presents a possible correlation with blowout fractures that should be further explored. The scoring sheet developed in this study establishes a standardized methodology for reporting orbital blowout fractures in contexts lacking soft tissue, providing a valuable tool for the consistent analysis of orbital trauma in bioarchaeology.
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Návrh stykače VN pro trakční účely / Design of MV contactor for railway applicationPala, Lukáš January 2021 (has links)
In the introduction a traction circuit is analyzed with different types of electric devices. The thesis describes power railway electric circuits, their loads and types of used contactors. Railway standards chapter summarizes requirements of standards for railway contactors. Follows literature focusing on power current switching and power switching devices design. Based on previous, a design procedure is developed for railway MV contactor in accordance with end-user and standards requirements. Thesis closes with pre-designing a railway contactor by calculating electrodynamic forces, heatflow and mechanical components.
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Analysis of Flame Blow-Out in Turbulent Premixed Ammonia/Hydrogen/Nitrogen - Air CombustionLakshmi Srinivasan (14228177) 08 December 2022 (has links)
<p> </p>
<p>With economies shifting towards net-zero carbon emissions, there is an increased interest in carbon-free energy carriers. Hydrogen is a potential carbon-free energy source. However, it poses several production, infrastructural, and safety challenges. Ammonia blends have been identified as a potential hydrogen carrier and fuel for gas turbine combustion. Partially cracked ammonia mixtures consist of large quantities of hydrogen that help overcome the disadvantages of pure ammonia combustion. The presence of nitrogen in the fuel blends leads to increased NO<sub>x</sub> emissions, and therefore lean premixed combustion is necessary to curb these emissions. Understanding the flame features, precursors, and dynamics of blowout of such blends due to lean conditions is essential for stable operation, lean blowout prediction, and control. </p>
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<p>In this study, high-fidelity large eddy simulations for turbulent premixed ammonia/hydrogen/nitrogen-air flames in an axisymmetric, unconfined, bluff-body stabilized burner are performed to gain insights into lean blowout dynamics. Partially cracked ammonia (40% NH<sub>3</sub>, 45% H<sub>2</sub>, and 15% N<sub>2</sub>, by volume) is chosen as fuel since its laminar burning velocity is comparable to CH4-air mixtures. A finite rate chemistry model with a detailed chemical kinetic mechanism (36 species and 247 reactions) is utilized to capture characteristics of various species during blowout. A comprehensive study of the flow field and flame structure for a weakly stable burning at an equivalence ratio of 0.5 near the blowout limit is presented. Further, the effects of blowout on the heat release rate, vorticity, distribution of major species, and ignition radicals are studied at four time instances at blowout velocity of 70 m/s. Since limited data is available on turbulent premixed combustion of partially cracked ammonia, such studies are essential in understanding flame behavior and uncertainties with regard to blowout.</p>
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