Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 170-180).

Thesis (M. Eng.(Mechanical))--University of Pretoria, 2003. / Includes summary. Includes bibliographical references (leaves 87-90).

Thesis (M.S.)--Brigham Young University. Dept. of Mechanical Engineering, 2005. / Includes bibliographical references (p. 103-105).

Thesis (M.S.)--Montana State University--Bozeman, 2005. / Typescript. Chairperson, Graduate Committee: M. Ruhul Amin. Includes bibliographical references (leaves 121-125).

No description available.

Gas turbine engineering faces many challenges in the constant strive to increase not only the efficiency of engines but also the various stages of development and design. Development of combustors have primarily consisted of empirical or semi-empirical modelling combined with experimental investigations. Due to the associated costs and development time a need exists for an alternative method of development. Although experimental investigations can never be substituted completely, mathematical models incorporating numerical methods have shown to be an attractive alternative to conventional combustor design methods. The purpose of this study is twofold: firstly, to experimentally investigate the physical properties associated with a research combustor that is geometrically representative of practical combustors; and secondly, to use the experimental measurements for the validation of a computational fluids dynamic model that was developed to simulate the research combustor using a commercial code. The combustor was tested at atmospheric conditions and is representative of practical combustors that are characterized by a turbulent, three-dimensional flow field. The single can combustor is divided into a primary, secondary and dilution zone, incorporating film¬cooling air through stacked rings and an axial swirler centred around the fuel atomizer. Measurements at different air/fuel ratios captured the thermal field during operating conditions and consisted of inside gas, liner wall and exit gas temperatures. An investigation of the different combustion models available, led to the implementation of the presumed-PDF model of unpremixed turbulent reaction. The computational grid included the external and internal flow field with velocity boundary conditions prescribed at the various inlets. Two-phase flow was not accounted for with the assumption made that the liquid fuel is introduced into the combustion chamber in a gas phase. Experimental results showed that incomplete combustion occurs in the primary zone, thereby reducing the overall efficiency. Also evident from the results obtained are the incorrect flow splits at the various inlets. Evaluation of the numerical model showed that gas temperatures inside the combustor are overpredicted. However, the numerical model is capable of capturing the correct distributions of temperatures and trends obtained experimentally. This study is successful in capturing detail temperature measurements that will be used for validation purposes to assist the development of a numerical model that can accurately predict combustion properties. / Dissertation (M Eng (Mechanical Engineering))--University of Pretoria, 2007. / Mechanical and Aeronautical Engineering / unrestricted

No description available.

In the power generation sector, more specifically, the gas turbine industry, competition has forced the lead time-to-market for product advancements to be more important than ever. For design engineers, this means that product design iterations and final product development must be completed within both critical time windows and budgetary constraints. Therefore, two areas that have received significant attention in the research and in practice are: (1) rapid prototyping technology development, and (2) rapid prototyping technology selection. Rapid prototyping technology selection is the focus of this research. In practice, selecting the rapid prototyping method that is acceptable for a specific design application is a daunting task. With technological advancements in both rapid prototyping and conventional machining methods, it is difficult for both a novice design engineer as well as an experienced design engineer to decide not only what rapid prototyping method could be applicable, but also if a rapid prototyping method would even be advantageous over a more conventional machining method and where in the manufacturing process any of these processes would be utilized. This research proposes an expert system that assists a design engineer through the decision process relating to the investment casting of a superalloy gas turbine engine component. Investment casting is a well-known technique for the production of many superalloy gas turbine parts such as gas turbine blades and vanes. In fact, investment-cast turbine blades remain the state of the art in gas turbine blade design. The proposed automated expert system allows the engineer to effectively assess rapid prototyping iii opportunities for desired gas turbine blade application. The system serves as a starting point in presenting an engineer with commercially-available state-of-the-art rapid prototyping options, brief explanations of each option and the advantages and disadvantages of each option. It is not intended to suggest an optimal solution as there is not only one unique answer. For instance, cost and time factors vary depending upon the individual needs of a company at any particular time as well as existing strategic partnerships with particular foundries and vendors. The performance of the proposed expert system is assessed using two real-world case studies. The first case study shows how the expert system can advise the design engineer when suggesting rapid manufacturing in place of investment casting. The second case study shows how rapid prototyping can be used for creating part patterns for use within the investment casting process. The results from these case studies are telling in that their implementations potentially result in an 82 to 94% reduction in design decision lead time and a 92 to 97% cost savings.

Clearances between gas turbine casings and rotating blades is of quite importance on turbo machines since a significant loss of efficiency can occur if the clearances are not predicted accordingly. The radial thermal growths of the blade may be over or under predicted if poor assumptions are made on calculating the metal temperatures of the surfaces exposed to the fluid. The external surface of the blade is exposed to hot gas temperatures and it is internally cooled with air coming from the compressor. This cold air enters the radial channels at the root of the blade and then exists at the tip. To obtain close to realistic metal temperatures on the blade, the Conjugate Heat Transfer (CHT) approach would be utilized in this research. The radial thermal growth of the blade would be then compared to the initial guess. This work focuses on the interaction between the external boundary conditions obtained from the commercial Computational Fluid Dynamics software package CFX, the internal boundary conditions along the channels from a 1D flow solver proprietary to Siemens Energy, and the 3D metal temperatures and deformation of the blade predicted using the commercial Solid Mechanics software package ANSYS. An iterative technique to solve CHT problems is demonstrated and discussed. The results of this work help to highlight the importance of CHT in predicting metal temperatures and the implications it has in other aspect of the gas turbine design such as the tip clearances.

The erosion damage to stator and rotor blades associated with flow containing particulates in turbines is investigated. The main parameters studied are blade leading edge thickness, blade turning angle, turbine inlet temperature, particle size, and particle densities. The computer programs used in the investigation are based on inviscid flow theory. Flow velocities relative to blades ranged up to sonic values. Results predict that decreasing flow turning angles and increasing blade leading edge thicknesses are the most effective ways to reduce erosion damage caused by impacting particles. Decreasing particle sizes and densities can also significantly reduce erosion rates. The erosion model uses the brittle and ductile mode response exhibited by materials subjected to particle impacts to predict the total erosion damage. The accuracy for small (1 micron) particles is questionable since some of these particles will have long residence times in the boundary layers, causing deposition rather than erosion. / Master of Science