ESRDC ship notional baseline Medium Voltage Direct Current (MVDC) architecture thermal simulation and visualization

This work presents a fast visualization and thermal simulation tool developed as part of the Electric Ship Research and Development Consortium (ESRDC) funded by the Office of Naval Research (ONR) that is capable of providing quick responses during early stages of ship design. The tool allows for the visualization of thermal and electrical loads, and equipment locations and other variables of interest in the all-electric ship, proceeding to the computation of the resulting whole ship temperature and relative humidity distribution. For that, a previously developed simplified physical model [1-3] -- which combines principles of classical thermodynamics and heat transfer, resulting in a system of three-dimensional differential equations which are discretized in space using a three-dimensional cell centered finite volume scheme -- is enhanced to include fresh and sea water cooled systems throughout the ship. Therefore, the combination of the proposed simplified physical model with the adopted finite volume scheme for the numerical discretization of the differential equations is called a volume element model (VEM). A 3D simulation is performed in order to determine the temperature distribution inside the ship for the baseline Medium Voltage Direct Current (MVDC) architecture, and representative operating conditions are analyzed. VisIt visualization tool [4] is used to plot the results.United States. Office of Naval Research (Grant N00014-08-1-0080

Modular machinery arrangement and its impact in early-stage naval electric ship design

Thesis (S.M. in Naval Architecture and Marine Engineering)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 75-77).Electrical power demands for naval surface combatants are projected to rise with the development of increasingly complex and power intensive combat systems. This trend also coincides with the need of achieving maximum fuel efficiency at both high and low hull speeds. A proposed solution to meet current and future energy needs of conventionally powered naval surface combatants is through the use of an Integrated Power System (IPS), which is seen as the next evolution in naval ship design. Unfortunately, historically-based ship design process models and parametrics cannot accommodate new-concept designs that are not incremental changes to previous practice. Additionally, integrating IPS with the next generation of ship designs is also synonymous with the desire of conducting system-level tradeoffs early within the ship design process. In an effort to enhance the relationship between new-concept designs and historically-based ship design processes, this thesis focuses on a novel approach of incorporating IPS at the earliest stage of the design process as part of assessing system-level tradeoffs early. This thesis describes a methodology for the system design and arrangement of an IPS machinery plant based on an objective of meeting a desired power generation level, effectively introducing a power constraint at the start of the design process. In conjunction with the methodology development, a hierarchical process and design tool for integration with Graphics Research Corporation's (GRC) naval architecture software suite, Paramarine, is also produced to assist in rapid development and evaluation of various IPS arrangements. The result of this process, through several case studies, provides insight into equipment selection philosophy, the initial sizing of the ship's machinery box, and the initial definition of electrical zones. Lastly, the developed tool is also used to aid in the creation of "design banks," allowing the naval architect to manage weight, power, and volume at the beginning of the ship design process; therefore, supporting early system-level tradeoffs for new-concept designs.by David J. Jurkiewicz.S.M.S.M.in Naval Architecture and Marine Engineerin

The Pressure Peaking Phenomenon for Ignited Under-Expanded Hydrogen Jets in the Storage Enclosure: Experiments and Simulations for Release Rates of up to 11.5 g/s

This work focuses on the experimental and numerical investigation of maximum overpressure and pressure dynamics during ignited hydrogen releases in a storage enclosure, e.g., in marine vessel or rail carriage, with limited vent size area, i.e., the pressure peaking phenomenon (PPP) revealed theoretically at Ulster University in 2010. The CFD model previously validated against small scale experiments in a 1 m3 enclosure is employed here to simulate real-scale tests performed by the University of South-Eastern Norway (USN) in a chamber with a volume of 15 m3. The numerical study compares two approaches on how to model the ignited hydrogen release conditions for under-expanded jets: (1) notional nozzle concept model with inflow boundary condition, and (2) volumetric source model in the governing conservation equations. For the test with storage pressure of 11.78 MPa, both approaches reproduce the experimental pressure dynamics and the pressure peak with a maximum 3% deviation. However, the volumetric source approach reduces significantly the computational time by approximately 3 times (CFL = 0.75). The sensitivity analysis is performed to study the effect of CFL number, the size of the volumetric source and number of iterations per time step. An approach based on the use of a larger size volumetric source and uniform coarser grid with a mesh size of a vent of square size is demonstrated to reduce the duration of simulations by a factor of 7.5 compared to the approach with inflow boundary at the notional nozzle exit. The volumetric source model demonstrates good engineering accuracy in predicting experimental pressure peaks with deviation from −14% to +11% for various release and ventilation scenarios as well as different volumetric source sizes. After validation against experiments, the CFD model is employed to investigate the effect of cryogenic temperature in the storage on the overpressure dynamics in the enclosure. For a storage pressure equal to 11.78 MPa, it is found that a decrease of storage temperature from 277 K to 100 K causes a twice larger pressure peak in the enclosure due to the pressure peaking phenomenon

Modeling and Simulation Roadmap to Enhance Electrical Energy security of U.S. Naval Bases

The enhancement of the electrical energy security of Navy bases within the continental U.S. has been studied using an approach based on modeling and simulation, with the intent to achieve real time control and energy management. The commercially available software packages are reviewed and the most suitable ones are indicated. A notional base was developed and used for this study. Its format is general enough to be able to be used as a template for each specific Navy installation. Several preliminary simulations using commercial software have been performed on the power system of this notional base addressing a variety of operating scenarios including islanded mode and the impact of wind and solar power sources. Results of steady state and transient operation are also reviewed. The results of these simulations indicate that existing software packages available today, with proper adaptations, can provide a well validated and consistent process for evaluating power system architectures and technologies and, therefore, can become a valuable tool for the implementation of the described plan for Navy bases. The study concludes giving the details of the roadmap to move forward in the process of energy security enhancement of U.S. Navy bases through modeling and simulation.Center for Electromechanic

STATE OF THE ART AND RESEARCH PRIORITIES IN HYDROGEN SAFETY

Wide spread deployment and use of hydrogen and fuel cell technologies can occur only if hydrogen safety issues have been addressed in order to ensure that hydrogen fuel presents the same or lower level of hazards and associated risk compared to conventional fuel technologies. To achieve this goal, hydrogen safety research should be directed to address the remaining knowledge gaps using risk-informed approaches to develop engineering solutions and Regulation Codes and Standards (RCS) requirements that meet individual and societal risk acceptance criteria, yet are cost-effective and market-competitive. IA HySafe and JRC IET partnered to organize a Research Priorities Workshop in Berlin on October 16-17, 2012 hosted by BAM (on behalf of IA HySafe) to address knowledge gaps in CFD modelling of hydrogen safety issues. The findings of the workshop are described in the report. The document aims to become a reference document for researchers/scientists and technical (including industry) experts working in the area worldwide. It is also a welcomed contribution for the Fuel Cell and Hydrogen Joint Undertaking (FCH JU) and for other funding bodies/organizations that must make decisions on research programmes and during the selection/choice of projects to be financially supported pursuing the safe use of hydrogen within Horizon 2020 framework.JRC.F.2-Energy Conversion and Storage Technologie

Survey of Concurrent Engineering Environments and the Application of Best Practices towards the Development of a Multiple Industry, Multiple Domain Environment

This thesis investigates the best practices of fifteen existing Concurrent Engineering Environments (CEE). A CEE is defined as any environment, from physical to virtual, designed to facilitate concurrent engineering with multiple domain experts real time. All existing environments surveyed have been focused on the aerospace industry showing significant reductions in design time and cost. I have identified hardware, software, and peopleware as three major classifications as well as sixteen subcategories with which to compare the different CEEs. The success in reducing time and cost of designs seen in the aerospace industry with the introduction of CEEs can and should be leveraged into additional domains and industries. This thesis explores the attributes of existing environments, the needs of additional industries, and the recommended concurrent engineering environment configuration appropriate for a multi-industry/multi-domain focus

Advanced Simulation Methods for Occupant-Centric Building Design

Performance quantification through simulation has been particularly advantageous to building design, as it can be applied to non-existent buildings in the design process, allows for testing design variants under identical conditions, and demands much less resources as compared to physical measurements. Consequently, use of building simulation in the design process has evolved to – for example – establish and verify design performance, screen and optimize design parameters, and study robustness and adaptability in adverse conditions. In this context, the present chapter investigates how the state-of-the-art simulation-aided design procedures can contribute to realize occupant-centric design objectives. To this end, the chapter, first, discusses the ways in which simulation-aided design methods can represent occupants and capture their interactions with buildings’ environmental control systems. Subsequently, a number of key simulation-aided design methods and objectives are explored with a focus on the role of occupants. Finally, a carefully described prototypical building model serves to demonstrate and test the introduced occupant-centric simulation-aided design procedures

Planning cities for the post-carbon age : a metabolic analysis of the urban form

[Resumen] El siglo veinte ha sido la edad de las ciudades, en la cual han experimentado la mayor expansión de su historia. La concentración de personas y actividades ha permitido un avance tecnológico sin precedentes, una larga etapa de prosperidad económica y el desarrollo de la actividad cultural. Cada día, miles de personas emigran desde sus hogares rurales en busca de las oportunidades que ofrece la metrópolis. Sin embargo, el triunfo de la ciudad ha sido a costa de la degradación de otros parajes, externos a ella, ya que absorben recursos desde distancias cada vez más lejanas. Las ciudades han crecido como sistemas voraces, basadas en el consumismo, por lo que requieren un suministro constante de materiales, agua, alimentos y energía para sostener su actividad y economía. Como tema central de investigación, las ciudades han sido estudiadas desde casi todas las perspectivas posibles. Algunas investigaciones previas han propuesto una analogía ecológica para medir los flujos del sistema urbano, lo que supone entender la ciudad como un ecosistema con un metabolismo característico. Este sería un primer paso para discernir las variables espaciales que influyen en el consumo urbano de recursos externos. Sin embargo, estos estudios todavía no han podido establecer de forma inequívoca la conexión entre la estructura física de la ciudad y su comportamiento ambiental. La abstracción de los postulados teóricos y las interferencias de múltiples factores en el análisis empírico han limitado el número de certezas en la ciencia urbana. El objetivo de esta tesis es explorar los vínculos entre forma urbana y los patrones de demanda de energía, mediante la combinación de la capacidad de exploración de modelos teóricos con el pragmatismo derivado del estudio de casos reales. Para ello, se ha elaborado un modelo de evaluación energética a escala urbana, tratando de responder a la carencia de instrumentos específicos que permitan integrar análisis y el diseño. Esta aplicación se prueba y aplica en diferentes escenarios derivados de los casos de estudios. Las experiencias de regeneración en los Docklands de Londres y el Poblenou de Barcelona proporcionan un marco real para entender la lógica de las transformaciones morfológicas en las ciudades existentes, introduciendo nuevas variables y aspectos, aunque manteniendo el foco principal de la investigación en la relación entre energía y forma urbana.[Resumo] O século vinte foi a era das cidades, na cal experimentaron a maior expansión da súa historia. A concentración de persoas e actividades permitiu un avance tecnolóxico sen precedentes, unha longa etapa de prosperidade económica e o desenvolvemento da actividade cultural. Cada día, miles de persoas emigran dende os seus fogares rurais, en busca das oportunidades que ofrece a metrópole. Non obstante, o triunfo da cidade produciuse a custa da degradación ambiental doutros paraxes, externos a ela, xa que absorben recursos dende distancias cada vez máis afastadas. As cidades creceron como sistemas voraces, baseadas no consumismo, e requiren un fluxo constante de bens, auga, alimentos e enerxía para soster as súas actividades e a súa economía. Como tema central de investigación, as cidades foron analizadas dende case todas as perspectivas posibles. Algunhas investigacións previas propuxeron unha analoxía ecolóxica para medir os fluxos do sistema urbano, o que supuso entender a cidade coma un ecosistema cun metabolismo característico. Este sería un primeiro paso para discernir as variables espaciais que inflúen no consumo urbano de recursos. Non obstante, estes intentos de establecer unha conexión entre o comportamento das cidades e a súa estrutura física non son aínda concluíntes. A abstracción dos postulados teóricos e as interferencias de múltiples factores na análise empírica limitaron o número de certezas na ciencia urbana. O obxectivo desta tese é explorar os vínculos entre a forma urbana e os patróns de demanda de enerxía mediante a combinación da capacidade de exploración dos modelos teóricos coas aprendizaxes derivadas do estudio de casos reais. Elabórase un modelo de análise enerxético urbano para responder á carencia de instrumentos específicos de planificación que permitan integrar a análise e o deseño. Esta aplicación próbase e aplícase en diferentes escenarios de forma urbana derivados dos casos de estudos. As experiencias de rexeneración nos Docklands de Londres e o Poblenou de Barcelona proporcionan un marco real para entender a lóxica das transformacións morfolóxicas nas cidades existentes, introducindo novas variables e aspectos máis amplos, ainda que mantendo o foco principal da investigación na relación entre enerxía e forma urbana.[Abstract] The 20th century has been the age of cities, as they have experienced their greatest expansion over history. The concentration of people and activities has enabled unprecedented technological advance, economic prosperity and the enhancement of culture. Thousands of people move every day from their rural homes, looking for the opportunities provided in the metropolis. However, the triumph of the city has been achieved at the expense of external environments, as they draw to themselves resources from further and further distances. Cities have grown as voracious systems, highly based on consumerism thus requiring massive flows of goods, water, food and energy to sustain their activities. As a central field of research, cities have been studied from all possible perspectives. Previous investigations have proposed an ecological analogy to measure the flows of the urban system, understanding the city as an ecosystem with a characteristic metabolism. It was meant as a first step to discern the spatial variables that influence urban consumption patterns. Nevertheless, these attempts to establish a connection between the performance of cities and their physical structure have been inconclusive so far. The abstraction of theoretical postulates and the interferences of multiple factors in empirical observations have limited the number of certainties in current urban science. The aim of this thesis is to explore the links between the urban form and energy demand patterns by combining the exploratory capacity of theoretical models with the learning outcomes from real case studies. As new planning instruments are needed to integrate analysis into design, an urban energy mode and tool has been worked out. The application was then tested and applied on alternative urban form scenarios, derived from the case studies. The regeneration experiences in London Docklands and Barcelona Poblenou provide a framework to understand the logic of morphological transformations in existing cities, introducing further variables and broader issues while keeping the control on the primary focus of the investigation: the relation between energy and urban form

Research Naval Postgraduate School, v.13, no.1, February 2003

NPS Research is published by the Research and Sponsored Programs, Office of the Vice President and Dean of Research, in accordance with NAVSOP-35. Views and opinions expressed are not necessarily those of the Department of the Navy.Approved for public release; distribution is unlimited

Computational Tools and Facilities for the Next-Generation Analysis and Design Environment

This document contains presentations from the joint UVA/NASA Workshop on Computational Tools and Facilities for the Next-Generation Analysis and Design Environment held at the Virginia Consortium of Engineering and Science Universities in Hampton, Virginia on September 17-18, 1996. The presentations focused on the computational tools and facilities for analysis and design of engineering systems, including, real-time simulations, immersive systems, collaborative engineering environment, Web-based tools and interactive media for technical training. Workshop attendees represented NASA, commercial software developers, the aerospace industry, government labs, and academia. The workshop objectives were to assess the level of maturity of a number of computational tools and facilities and their potential for application to the next-generation integrated design environment