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No description available.

Type 11 hot corrosion has been identified as a major life limiting factor of gas turbine components in the topping cycle of coal fired combined cycle power plant. Impurities in the coal combustion gases provide the environmental contaminants necessary for type 11 hot corrosion to occur. It is the purpose of the present study to develop corrosion lifting models such that corrosion rates and thus component lives in coal fired combined cycle plant gas turbines may be accurately predicted thus minimising efficiency losses and plant downtime due to corrosion related problems. Type 11 hot corrosion has been shown to follow bi11lodal distributions which cannot be modelled using the well known mathematical models. It has been shown that a probabilistic approach to modelling is appropriate and that the Gumbel Type I extreme value model of maxima can be used to model the maximum extreme corrosion data This is appropriate as it is the maximum extreme corrosion which in life limiting in the plant gas turbine. Basic corrosion data has been generated through a series of laboratory hot corrosion tests designed to simulate the ambient conditions within the plant gas turbine. The variables having most influence on the corrosion process have been identified as ; temperature, thermal cycling, alkali (Na + K) metal sulphate deposition rate, S02 and HCl in the ambient atmosphere. The corrosion models have been developed from this data which accurately predict the type 11 hot corrosion rates observed in the coal fired gas turbine of a combined cycle power plant.

Two linear combination models for the transition zone in two-dimensional incompressible boundary layers have been programmed into the commercially available computational fluid dynamics software suite of programs, PHOENICS as a sink of momentum. It has been shown that it was possible to use a laminar velocity profile to predict laminar, transitional and turbulent boundary layer parameters. Method one, attributable to Fraser, Higazy and Milne (1994), was tested against a variety of flows including zero and constant adverse and favourable pressure gradients, and also the varying pressure gradient Rolls Royce T3C flows. The method gives good prediction of skin friction and transition length when the start of transition was in zero and favourable pressure gradient flows, but the transition length was always under predicted when the start of transition was in adverse pressure gradient. Method two, attributable to Solomon, Walker and Gostelow (1995) was tested in flows where the start of transition was in adverse pressure gradient. This method will probably give an improved prediction o f transition length, but the results were highly sensitive to the properties of the flow at the start of transition. It has been shown that in order to predict the start of transition using the Abu-Ghannam and Shaw (1980) correlation, a meaningful average of free stream turbulence intensity in the flow was required. It was found that a reasonable estimate could be found by integrating the free stream intensity value from the inlet and taking the average. A new method was developed to overcome the limitations of the Abu-Ghannam and Shaw correlation, and is based on the turbulent energy equation. The method used integrated averages of properties across the boundary layer starting from the leading edge and marching downstream. The boundary layer model was coupled to the free stream by a correlation which was found, using the Rolls Royce T3A, T3A-, T3B and T3C data, to be a function of free stream turbulence intensity, dissipation length scale and pressure gradient parameter. The method was found to give good prediction of the start of transition, and hence skin friction in the favourable pressure gradient flows. Unfortunately there was not enough data to extend this correlation to adverse pressure gradients.

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No description available.

Thesis (Ph.D.)--University of Delaware, 2006. / Principal faculty advisor: Anette M. Karlsson, Dept. of Mechanical Engineering. Includes bibliographical references.

Thesis (M.S.)--Naval Postgraduate School, 2002. / Thesis advisor(s): Knox T. Millsaps. Includes bibliographical references (p. 41). Also available online.

Thesis (M.S.)--Brigham Young University. Dept. of Mechanical Engineering, 2004. / Includes bibliographical references (p. 107-110).

Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, December 2003. / Thesis advisor(s): Knox T. Millsaps, Jr. Includes bibliographical references (p. 49-50). Also available online.