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MULTIOBJECTIVE DESIGN OPTIMIZATION OF GAS TURBINE BLADE WITH EMPHASIS ON INTERNAL COOLING
Title
MULTIOBJECTIVE DESIGN OPTIMIZATION OF GAS TURBINE BLADE WITH EMPHASIS ON INTERNAL COOLING.
Creator
Nagaiah, Narasimha, Geiger, Christopher, Nazzal, Dima, Reilly, Charles, Kapat, Jayanta, University of Central Florida
Abstract / Description
In the design of mechanical components, numerical simulations and experimental methods are commonly used for design creation (or modification) and design optimization. However, a major challenge of using simulation and experimental methods is that they are time-consuming and often cost-prohibitive for the designer. In addition, the simultaneous interactions between aerodynamic, thermodynamic and mechanical integrity objectives for a particular component or set of components are difficult to...
Show moreIn the design of mechanical components, numerical simulations and experimental methods are commonly used for design creation (or modification) and design optimization. However, a major challenge of using simulation and experimental methods is that they are time-consuming and often cost-prohibitive for the designer. In addition, the simultaneous interactions between aerodynamic, thermodynamic and mechanical integrity objectives for a particular component or set of components are difficult to accurately characterize, even with the existing simulation tools and experimental methods. The current research and practice of using numerical simulations and experimental methods do little to address the simultaneous (")satisficing(") of multiple and often conflicting design objectives that influence the performance and geometry of a component. This is particularly the case for gas turbine systems that involve a large number of complex components with complicated geometries.Numerous experimental and numerical studies have demonstrated success in generating effective designs for mechanical components; however, their focus has been primarily on optimizing a single design objective based on a limited set of design variables and associated values. In this research, a multiobjective design optimization framework to solve a set of user-specified design objective functions for mechanical components is proposed. The framework integrates a numerical simulation and a nature-inspired optimization procedure that iteratively perturbs a set of design variables eventually converging to a set of tradeoff design solutions. In this research, a gas turbine engine system is used as the test application for the proposed framework. More specifically, the optimization of the gas turbine blade internal cooling channel configuration is performed. This test application is quite relevant as gas turbine engines serve a critical role in the design of the next-generation power generation facilities around the world. Furthermore, turbine blades require better cooling techniques to increase their cooling effectiveness to cope with the increase in engine operating temperatures extending the useful life of the blades.The performance of the proposed framework is evaluated via a computational study, where a set of common, real-world design objectives and a set of design variables that directly influence the set of objectives are considered. Specifically, three objectives are considered in this study: (1) cooling channel heat transfer coefficient, which measures the rate of heat transfer and the goal is to maximize this value; (2) cooling channel air pressure drop, where the goal is to minimize this value; and (3) cooling channel geometry, specifically the cooling channel cavity area, where the goal is to maximize this value. These objectives, which are conflicting, directly influence the cooling effectiveness of a gas turbine blade and the material usage in its design. The computational results show the proposed optimization framework is able to generate, evaluate and identify thousands of competitive tradeoff designs in a fraction of the time that it would take designers using the traditional simulation tools and experimental methods commonly used for mechanical component design generation. This is a significant step beyond the current research and applications of design optimization to gas turbine blades, specifically, and to mechanical components, in general.
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Date Issued
2012
Identifier
CFE0004495, ucf:49282
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0004495
Species and habitat interactions of the gopher tortoise: A keystone species?
Title
Species and habitat interactions of the gopher tortoise: A keystone species?.
Creator
Catano, Christopher, Hinkle, Charles, Stout, I, Jenkins, David, University of Central Florida
Abstract / Description
Species-species and species-habitat interactions have been demonstrated to be important in influencing diversity across a variety of ecosystems. Despite generalities in the importance of these interactions, appropriate mechanisms to explain them are absent in many systems. In sandhill systems of the southeast U.S., gopher tortoises have been hypothesized to be a crucial species in the maintenance of diversity and function. However, the mechanisms and magnitude in which they influence their...
Show moreSpecies-species and species-habitat interactions have been demonstrated to be important in influencing diversity across a variety of ecosystems. Despite generalities in the importance of these interactions, appropriate mechanisms to explain them are absent in many systems. In sandhill systems of the southeast U.S., gopher tortoises have been hypothesized to be a crucial species in the maintenance of diversity and function. However, the mechanisms and magnitude in which they influence their communities and habitats have rarely been empirically quantified. I examined how habitat structure influences tortoise abandonment of burrows and how tortoise densities influence non-volant vertebrate community diversity. Tortoise burrow abandonment is directly influenced by canopy closure, with each percent increase in canopy cover relating to a ~2% increase in the probability of burrow abandonment. In addition, tortoise burrow density was positively correlated with diversity and evenness, but not species richness. This influence was directly proportional to burrow density, supporting a dominance role for this species and rejecting the commonly asserted keystone species mechanism. I also quantified the influence of tortoises in influencing diversity relative to other environmental and habitat variables. Through this research, I have demonstrated that disturbance and habitat structure are important, but diversity responds most to density of burrows in the habitat. These findings demonstrate the intricate relationships interacting to maintaining diversity in sandhill systems. In particular, habitat change leading to declines of gopher tortoises may have drastic negative impacts on vertebrate species diversity.
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Date Issued
2012
Identifier
CFE0004526, ucf:49246
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0004526
Assessment, Optimization, and Enhancement of Ultrafiltration (UF) Membrane Processes in Potable Water Treatment
Title
Assessment, Optimization, and Enhancement of Ultrafiltration (UF) Membrane Processes in Potable Water Treatment.
Creator
Boyd, Christopher, Duranceau, Steven, Cooper, Charles, Randall, Andrew, University of Central Florida
Abstract / Description
This dissertation reports on research related to ultrafiltration (UF) membranes in drinking water applications. A pilot-scale investigation identified seasonal surface water quality impacts on UF performance and resulted in the development of a dynamic chemically enhanced backwash protocol for fouling management. Subsequent analysis of UF process data revealed limitations with the use of specific flux, transmembrane pressure (TMP), and other normalization techniques for assessing UF process...
Show moreThis dissertation reports on research related to ultrafiltration (UF) membranes in drinking water applications. A pilot-scale investigation identified seasonal surface water quality impacts on UF performance and resulted in the development of a dynamic chemically enhanced backwash protocol for fouling management. Subsequent analysis of UF process data revealed limitations with the use of specific flux, transmembrane pressure (TMP), and other normalization techniques for assessing UF process fouling. A new TMP balance approach is presented that identifies the pressure contribution of membrane fouling and structural changes, enables direct process performance comparisons at different operating fluxes, and distinguishes between physically and chemically unresolved fouling. In addition to the TMP balance, a five component optimization approach is presented for the systematic improvement of UF processes on the basis of TMP variations. Terms are defined for assessing process event performance, a new process utilization term is presented to benchmark UF productivity, and new measures for evaluating maintenance procedures are discussed. Using these tools, a correlation between process utilization and operating pressures was established and a sustainable process utilization of 93.5% was achieved. UF process capabilities may be further enhanced by pre-coating media onto the membrane surface. Silicon dioxide (SiO2) and powdered activated carbon (PAC) are evaluated as pre-coating materials, and the applicability of the TMP balance for assessing pre-coated membrane performance is demonstrated. The first use of SiO2 as a support layer for PAC in a membrane pre-coating application is presented at the laboratory-scale. SiO2-PAC pre-coatings successfully reduced physically unresolved fouling and enhanced UF membrane organics removal capabilities.
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Date Issued
2013
Identifier
CFE0005088, ucf:50758
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005088
Keeping Quiet: Investigating the Maintenance and Policing of Male-dominated Gaming Space
Title
Keeping Quiet: Investigating the Maintenance and Policing of Male-dominated Gaming Space.
Creator
Charles, Christopher, Pritchard, Robert, Preston-Sidler, Leandra, Grauerholz, Liz, Corzine, Harold, University of Central Florida
Abstract / Description
Despite the near parity between the number of female and male gamers (Entertainment Software Association, 2014), studies on gender in videogames illustrate a culture that typically reflects hegemonic masculinity and excludes women on a multitude of levels. Because these interactions occur within real and virtual space (both online and within games), a holistic approach is warranted to analyze these mechanisms of oppression. This paper seeks to uncover the ways by which gaming culture is...
Show moreDespite the near parity between the number of female and male gamers (Entertainment Software Association, 2014), studies on gender in videogames illustrate a culture that typically reflects hegemonic masculinity and excludes women on a multitude of levels. Because these interactions occur within real and virtual space (both online and within games), a holistic approach is warranted to analyze these mechanisms of oppression. This paper seeks to uncover the ways by which gaming culture is maintained and policed as a male-dominated space, through qualitative data collection. By using ethnographic, participant observation at a large, multi-genre convention the experiences of both male and female gamers were collected and analyzed. Their stories shed light on the means by which women are silenced, or (")kept quiet,(") by voice chat profiling, verbal abuse, and hostile Internet communities. They are subject to strict policing of gamer identity, relegation as casual gamers, and their calls for inclusiveness all too often fall on game developers' deaf ears.
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Date Issued
2016
Identifier
CFE0006281, ucf:51605
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006281