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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
171

Thin film sensor techniques for the instrumentation of ceramic/metal interfaces in next generation aero gas turbines

Shepherd, Richard Stephen January 1999 (has links)
The growth of thrust and improved aeroengine efficiency has been gained by increased temperatures throughout the engine. This has been achieved by improved material technology and the continuous cooling of components complemented by the addition of thermal barrier coatings (TBC) to turbine and combustion chamber components. The aggressive nature of the application process of the TBC has previously made the measurement of metal surface temperature and strain exceedingly difficult on components to which it is applied. In the present study magnetron sputter-deposited thin film sensor techniques have been developed specifically for compressor and turbine applications of noble metal thermocouples and strain gauges. The deposition, patterning and evaluation of reactively sputtered aluminium oxide, type R platinum thermocouples as well as PdCr and PtW dynamic strain gauges is reported. A sputtered NiCoCrAlY coating has been developed to replace the vacuum plasma spray process currently used in the TBC system. The most favourable location for the thin film sensor is at the metal/ceramic interface of the TBC system. However, in order to protect the sensor from the aggressive TBC process, the sensor has been deposited in a novel installation between two layers of NiCoCrAlY bond coat. Several trials have been performed to fabricate this package on turbine blade material substrates. This work has demonstrated that the proposed sensor structure is feasible. However there are problems with delamination due to contamination and residual stress and with poor electrical insulation and these have limited the high temperature testing that could be performed. The novel techniques developed are already being utilised in measurement applications on components without TBCs. This work has been performed in an industrial context. The extensive project and risk management activities are reported.
172

A method for aircraft afterburner combustion without flameholders

Birmaher, Shai 02 March 2009 (has links)
State of the art aircraft afterburners employ spray bars to inject fuel and flameholders to stabilize the combustion process. Such afterburner designs significantly increase the length (and thus weight), pressure losses, and observability of the engine. This thesis presents a feasibility study of a compact prime and trigger (PAT) afterburner concept that eliminates the fuel spray bars and flameholders and, thus, eliminates the above-mentioned problems. In this concept, afterburner fuel is injected just upstream or in between the turbine stages. Downstream of the turbine stages, a low power pilot, or trigger , can be used to control the combustion process. The envisioned trigger for the PAT concept is a jet of product gas from ultra-rich hydrocarbon/air combustion that is injected through the afterburner liner. This partial oxidation (POx) gas, which consists mostly of H2, CO, and diluents, rapidly produces radicals and heat that accelerate the autoignition of the primed mixture and, thus, provide an anchor point for the afterburner combustion process. The objective of this research was to demonstrate the feasibility of the PAT concept by showing that (1) combustion of fuel injected within or upstream of turbine stages can occur only downstream of the turbine stages, and (2) the combustion zone is compact, stable and efficient. This was accomplished using two experimental facilities, a developed theoretical model, and Chemkin simulations. The first facility, termed the Afterburner Facility (AF), simulated the bulk flow temperature, velocity and O2 content through a turbojet combustor, turbine stage and afterburner. The second facility, termed the Propane Autoignition Combustor (PAC), was essentially a scaled-down, simplified version of the AF. The developed model was used to predict and interpret the AF results and to study the feasibility of the PAT concept at pressures outside the AF operating range. Finally, the Chemkin simulations were used to study the effect of several POx gas compositions on the afterburner combustion process.
173

Numerical Methods for Turbomachinery Aeromechanical Predictions

Mayorca, Maria Angelica January 2011 (has links)
In both aviation and power generation, gas turbines are used as key components. An important driver of technological advance in gas turbines is the race towards environmentally friendly machines, decreasing the fuel burn, community noise and NOx emissions. Engine modifications that lead to propulsion efficiency improvements whilst maintaining minimum weight have led to having fewer stages and lower blade counts, reduced distance between blade rows, thinner and lighter components, highly three dimensional blade designs and the introduction of integrally bladed disks (blisks). These changes result in increasing challenges concerning the structural integrity of the engine. In particular for blisks, the absence of friction at the blade to disk connections decreases dramatically the damping sources, resulting in designs that rely mainly on aerodynamic damping. On the other hand, new open rotor concepts result in low blade-to-air mass ratios, increasing the influence of the surrounding flow on the vibration response.   This work presents the development and validation of a numerical tool for aeromechanical analysis of turbomachinery (AROMA - Aeroelastic Reduced Order Modeling Analyses), here applied to an industrial transonic compressor blisk. The tool is based on the integration of results from external Computational Fluid Dynamics (CFD) and Finite Element (FE) solvers with mistuning considerations, having as final outputs the stability curve (flutter analysis) and the fatigue risk (forced response analysis). The first part of the study aims at tracking different uncertainties along the numerical aeromechanical prediction chain. The amplitude predictions at two inlet guide vane setups are compared with experimental tip timing data. The analysis considers aerodynamic damping and forcing from 3D unsteady Navier Stokes solvers. Furthermore, in-vacuo mistuning analyses using Reduced Order Modeling (ROM) are performed in order to determine the maximum amplitude magnification expected. Results show that the largest uncertainties are from the unsteady aerodynamics predictions, in which the aerodynamic damping and forcing estimations are most critical. On the other hand, the structural dynamic models seem to capture well the vibration response and mistuning effects.   The second part of the study proposes a new method for aerodynamically coupled analysis: the Multimode Least Square (MLS) method. It is based on the generation of distributed aerodynamic matrices that can represent the aeroelastic behavior of different mode-families. The matrices are produced from blade motion unsteady forces at different mode-shapes fitted in terms of least square approximations. In this sense, tuned or mistuned interacting mode families can be represented. In order to reduce the domain size, a static condensation technique is implemented. This type of model permits forced response prediction including the effects of mistuning on both the aerodynamic damping as well as on the structural mode localization. A key feature of the model is that it opens up for considerations of responding mode-shapes different to the in-vacuo ones and allows aeroelastic predictions over a wide frequency range, suitable for new design concepts and parametric studies. / QC 20111125 / Turbopower, AROMA
174

Refractory metal to nickel-based alloy joining technologies for high temperature applications

Callender, Chad M., January 2006 (has links) (PDF)
Thesis(M.S.)--Auburn University, 2006. / Abstract. Vita. Includes bibliographic references.
175

Effects of high levels of steam addition on NOx̳ reduction in laminar opposed flow diffusion flames /

Blevins, Linda G., January 1992 (has links)
Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / On t.p. "x̳" is subscript. Vita. Abstract. Includes bibliographical references (leaves 92-97). Also available via the Internet.
176

Effects of fluid properties on the aerodynamic performance of turbomachinery for semi-closed cycle gas turbine engines using O2/CO2 combustion /

Roberts, Stephen Keir, January 1900 (has links)
Thesis (M. App. Sc.)--Carleton University, 2002. / Includes bibliographical references (p. 144-148). Also available in electronic format on the Internet.
177

Influence of loading distribution on the performance of high pressure turbine blades /

Corriveau, Daniel, January 1900 (has links)
Thesis (Ph.D.) - Carleton University, 2005. / Includes bibliographical references (p. 295-301). Also available in electronic format on the Internet.
178

Application of artificial intelligence in gas turbine control and modelling.

Daher, Roni. January 1900 (has links)
Thesis (M.App.Sc.) - Carleton University, 2005. / Includes bibliographical references (p. 110-115). Also available in electronic format on the Internet.
179

Maximizing the performance of semi-closed O2/CO2 turbine combined cycles for power generation /

Allaby, Lorne G. January 1900 (has links)
Thesis (M.App.Sc.) - Carleton University, 2006. / Includes bibliographical references (p. 217-230). Also available in electronic format on the Internet.
180

An experimental investigation of the conversion of NO to NO₂ in a simulated gas turbine environment /

Hunderup, James W., January 1993 (has links)
Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 121-123). Also available via the Internet.

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