Thesis (Ph.D.)--Tennessee Technological University, 2006. / Bibliography: leaves 126-129.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 63-65).

Thesis (Ph. D.)--Oregon State University, 1968. / Typescript (photocopy). Includes bibliographical references (leaves 107-110). Also available on the World Wide Web.

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Gas turbine combustors employing a single lean combustion stage represent the next generation of design for reduced NO_Xemissions. These lean-burn combustors rely on swirl-stabilised flames resulting in highly non-uniform outflows. Non-uniform conditions adversely affect high-pressure turbine performance. 3D numerical simulations provide a means to understand and optimise engine design, however, the modelling of turbulence means experimental validation is crucial. Turbine test facilities operating at scaled, non-reacting conditions, with simulated combustor flows are an important source of validation data. This thesis presents advances in combustor simulator design, testing and instrumentation relevant to the challenges of modern, highly-integrated turbine testing. The design of a lean-burn combustor simulator, characterised by swirl and non-uniform temperature, is presented. The design was based on measurements and predictions of engine conditions. Unsteady numerical simulations were employed as a predictive design tool. An engine-scale combustor simulator was manufactured and characterised experimentally in a bespoke facility. Surveys of flow structure are presented, focusing on experimental turbine inlet data. These data confirmed that the combustor simulator reproduces the important features of a lean-burn combustor; e.g. swirling mainstream flow and high turbulence intensity. The lean-burn combustor simulator will be the first of its kind to be implemented in a rotating turbine test facility, and will provide important validation data. Measurement techniques were developed alongside the core work. Miniaturised five-hole probe rakes for turbine inlet measurements were developed using additive manufacturing (AM). Building on this work, an open source AM five-hole probe design is presented with experimental validation. The problem of estimating pressure probe bandwidth was also addressed, and a simplified model is presented. These tools have direct applications in turbomachinery research.

This study uses CFD methodology to simulate an advanced Diesel engine operated at higher than conventional peak cylinder pressures. The existing mathematical models for Diesel combustion, pollutant formation and wall heat transfer are improved and validated for this operating range. The fluid flow is described via the gas-phase Favre-averaged transport equations, governing the conservation of mass, chemical species, momentum and energy, based on the Eulerian continuum framework. These equations are closed by means of the k — e turbulence model. The liquid phase uses the Lagrangian approach, in which parcels, representing a class of droplets, are described by differential equations for the conservation of mass, momentum and energy. The numerical solution of the gas phase is obtained by the finite volume method applied to unstructured meshes with moving boundaries. Diesel ignition is modeled via a reduced kinetics mechanism, coupled with a characteristic timescale combustion model. Additionally, NOx and soot emissions are simulated. For the elevated cylinder temperatures and pressures, the behaviour of the thermophysical properties of the gases and liquids involved is critically examined. A near-wall treatment is applied accounting for the large gradients of thermophysical properties in the vicinity of the wall. Furthermore an alternative combined combustion and emissions modelling approach, RIF, based on the laminar flamelet concept is tested. The methodology is validated by reference to experimental data from a research engine, a constant volume pressure chamber and a high-pressure DI Diesel engine at various operating conditions. The modified near-wall treatment gives better agreement with the heat transfer measurements. The methodology predicts Diesel combustion evolution reasonably well for the elevated pressures. Best agreement was achieved using the LATCT combustion model combined with a NOx and soot model. The predictions of emissions show encouraging trends especially regarding the soot/NOx tradeoff, but require tuning of model coefficients.

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The thesis is divided into four chapters. Chapter I gives a brief résumé of the state of rotational flow theory up to 1955. Chapter II contains a study of the constant shear flow past cylinders with various cross sections. Chapter III contains a method for obtaining the stream functions for cylinders in a variable shear flow when the latter approximates firstly to a linear vorticity distribution, and secondly to the rotational flow present in a boundary layer. Further, it illustrates the nature of the difficulties likely to be encountered in trying to obtain analytical solutions of problems where the rotation is of a more complicated nature. Finally, Chapter IV contains a relaxation solution to the two-dimensional isentropic compressible rotational flow of a gas through a channel containing a constriction, it also illustrates the complexity of the numerical work required in obtaining relaxation solutions of compressible flow problems with rotation.

The subject matter of this thesis is concerned with the stability of fluid flows; more particularly , with the stability of liquid films which have an interface with air. We will therefore begin by formulating the basic equations and ideas which pertain to this class of problems. Later in this chapter, a summary will be given of the topics dealt with in this dissertation.