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Increasing the combustion temperatures in a gas turbine engine to achieve higher efficiency and power output also results in high heat loads to turbine components downstream of the combustor. The challenge of adequately cooling the nozzle guide vane directly downstream of the combustor is compounded by a complex vortical secondary flow at the junction of the endwall and the airfoil. This flow tends to increase local heat transfer rates and sweep coolant away from component surfaces, as well as decrease the turbine aerodynamic efficiency. Past research has shown that a large fillet at the endwall-airfoil junction can reduce or eliminate the secondary flow. Also, leakage flow from the interface gap between the combustor and the turbine can provide some cooling to the endwall. This study examines the individual and combined effects of a large fillet and realistic combustor-turbine interface gap leakage flow for a nozzle guide vane. The first study focuses on the effect of leakage flow from the interface gap on the endwall upstream of the vane. The second study addresses the influence of large fillets at the endwall-airfoil junction, with and without upstream leakage flow. Both studies were performed in a large low-speed wind tunnel with the same vane geometry. Endwall shear stress measurements were obtained for various endwall-airfoil junction geometries without upstream leakage flow. Endwall heat transfer and cooling effectiveness were measured for various leakage flow rates and leakage gap widths, with a variety of endwall-airfoil junction geometries. Results from these studies indicate that the secondary flow has a large influence on the coverage area of the leakage coolant. Increased leakage flow rates resulted in better cooling effectiveness and coverage, but also higher heat transfer rates. The two fillet geometries tested affected coolant coverage by displacing coolant around the base of the fillet, which could result in undesirably high gradients in endwall temperature. The addition of a large fillet to the endwall-airfoil junction, however, reduced heat transfer, even when upstream leakage flow was present. / Master of Science

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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1979. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND AERONAUTICS. / Vita. / Includes bibliographical references. / Ph.D.

The deregulation of the electric power market introduced a strong element of competition. Power plant operators strive to develop advanced operational strategies to maximize the profitability in the dynamic electric power market. New methodologies for gas turbine power plant operational modeling and optimization are needed for power plant operation to enhance operational decision making, and therefore to maximize power plant profitability by reducing operations and maintenance cost and increasing revenue. In this study, a profit based, lifecycle oriented, and unit specific methodology for gas turbine based power plant operational modeling was developed, with the power plant performance, reliability, maintenance, and market dynamics considered simultaneously. The generic methodology is applicable for a variety of optimization problems, and several applications for operational optimization were implemented using this method. A multiple time-scale method was developed for gas turbine power plants long term generation scheduling. This multiple time-scale approach allows combining the detailed granularity of the day-to-day operations with global (seasonal) trends, while keeping the resulting optimization model relatively compact. Using the multiple timescale optimization method, a profit based outage departure planning method was developed, and the key factors for this profit based approach include power plant aging, performance degradation, reliability deterioration, and the energy market dynamics. A novel approach for gas turbine based power plant sequential preventive maintenance scheduling was also introduced. Finally, methods to evaluate the impact of upgrade packages on gas turbine power plant performance, reliability, and economics were developed, and TIES methodology was applied for effective evaluation and selection of gas turbine power plant upgrade packages.

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Thesis (Ph.D.) -- McMaster University, 1998. / Includes bibliographical references (leaves 206-210). Also available via World Wide Web.

Thesis (Ph. D.)--Carleton University, 2004. / Includes bibliographical references (p. 259-274). Also available in electronic format on the Internet.

Thesis (M.App.Sc.) - Carleton University, 2005. / Includes bibliographical references (p. 182-190). Also available in electronic format on the Internet.