No description available.

Film cooling is investigated on a flat plate both numerically and experimentally. Conical shaped film hole are investigated extensively and contribute to the current literature data, which is extremely rare in the open public domain. Both configuration of the cylindrical film holes, with and without a trench, are investigated in detail. Design of experiment technique was performed to find an optimum combination of both geometrical and fluid parameters to achieve the best film cooling performance. From this part of the study, it shows that film cooling performance can be enhanced up to 250% with the trenched film cooling versus non-trenched case provided the same amount of coolant. Since most of the relevant open literature is about film cooling on flat plate endwall cascade with linear extrusion airfoil, the purpose of the second part of this study is to examine the interaction of the secondary flow inside a 3D cascade and the injected film cooling jets. This is employed on the first stage of the aircraft gas turbine engine to protect the curvilinear (annular) endwall platform. The current study investigates the interaction between injected film jets and the secondary flow both experimentally and numerically at high Mach number (M=0.7). Validation shows good agreement between obtained data with the open literature. In general, it can be concluded that with an appropriate film coolant to mainstream blowing ratio, one can not only achieve the best film cooling effectiveness (FCE or η) on the downstream endwall but also maintain almost the same aerodynamic loss as in the un-cooled baseline case. Film performance acts nonlinearly with respect to blowing ratios as with film iv cooling on flat plate, in the other hand, with a right blowing ratio, film cooling performance is not affect much by secondary flow. In turn, film cooling jets do not increase pressure loss at the downstream wake area of the blades.

No description available.

Turbine manufacturers continually seek to gain efficiency by increasing operating temperatures well above the maximum temperature of component alloys. This increase in temperature must be accounted for in the cooling of components by examining the heat transfer from these crucial components. This study specifically examines the effect of a contoured endwall on the heat transfer of a scaled-up stator vane. Understanding the three-dimensional effects of contoured endwalls on vane heat transfer can lead to prolonging blade life. The results of a combined experimental and computational study of heat transfer along the surface of a turbine vane that incorporates a contoured endwall are discussed in detail. A commercially available computational fluid dynamics code was used to design a contoured endwall and simulate an engine representative pressure distribution for a turbine vane cascade placed in a low-speed wind tunnel. A significant flow acceleration caused by the contour increased heat transfer over 40% of the vane span compared to the vane far from the contoured endwall. The effects of freestream turbulence with respect to the contour were examined. Results showed a significant increase in heat transfer at elevated freestream turbulence levels at each span location. The effects of the contour were minimal compared to the effects of increased turbulence. The boundary layer transition location moved further upstream with increasing turbulence. Trip wires were used to model the effect of film-cooling holes on the boundary layer development. The heat transfer increased locally at the trip and either remained elevated if the boundary layer remained turbulent or the heat transfer decreased as the boundary layer relaminarized due to flow acceleration. These results are beneficial to turbine manufacturers interested in effective placement of film-cooling holes. / Master of Science

An experimental facility was designed and benchmarked that could simulate the non-uniformities in the flow and thermal fields exiting real gas-turbine combustors. The design of the combustor simulator required analyses of the flow paths within a real combustor in a gas turbine engine. Modifications were made to an existing wind tunnel facility to allow for the installation of the combustor simulator. The overall performance of the simulator was then benchmarked through measurements of velocity, pressure, temperature, and turbulence using a straight exit test section to provide a baseline set of data. Comparisons of the measured quantities were made between two test cases that included a flow field with and without dilution flow.One of the major findings from this study was that the total pressure profiles exiting the combustor simulator in the near-wall region were different from a turbulent boundary layer. This is significant since many studies consider a turbulent boundary layer as the inlet condition to the turbine. Turbulent integral length scales were found to scale well with the dilution hole diameters and no dominant frequencies were observed in the streamwise velocity energy spectra. Dilution flow resulted in an increase in turbulence levels and mixing causing a reduction in the variation of total pressure and velocity. Adiabatic effectiveness levels were significantly reduced for the case with dilution flow in both the near combustor exit region and along the axial length of the straight exit test section. / Master of Science

No description available.

Thesis (Master of Engineering in Electrical Engineering)--Cape Peninsula University of Technology, 2018. / Gas turbines have achieved widespread popularity in industrial fields. This is due to the high power, reliability, high efficiency, and its use of cheap gas as fuel. However, a major draw-back of gas turbines is due to the strong function of ambient air temperature with its output power. With every degree rise in temperature, the power output drops between 0.54 and 0.9 percent. This loss in power poses a significant problem for utilities, power suppliers, and co-generations, especially during the hot seasons when electric power demand and ambient temperatures are high. One way to overcome this drop in output power is to cool the inlet air temperature. There are many different commercially available means to provide turbine inlet cooling. This disserta-tion reviews the various technologies of inlet air cooling with a comprehensive overview of the state-of-the-art of inlet fogging systems. In this technique, water vapour is being used for the cooling purposes. Therefore, the water quality requirements have been considered in this thesis. The fog water is generally demin-eralized through a process of Reverse Osmosis (RO). The drawback of fogging is that it re-quires large amounts of demineralized water. The challenge confronting operators using the fogging system in remote locations is the water scarcity or poor water quality availability. However, in isolated hot areas with high levels of radiation making use of solar PV energy to supply inlet cooling system power requirements is a sustainable approach. The proposed work herein is on the development of a photovoltaic (PV) application for driv-ing the fogging system. The design considered for improved generation of Acaica power plant in Cape Town, South Africa. In addition, this work intends to provide technical infor-mation and requirements of the fogging system design to achieve additional power output gains for the selected power plant.

Thesis (M.S.)--Baylor University, 2005. / Includes bibliographical references (p. 124-128).

No description available.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 113-115). Also available via the Internet.