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In this thesis various aspects of the diesel engine fuel injection, combustion and emission formation processes have been evaluated. Several types of evaluation tools and methods have been applied. Fuel spray momentum was used to characterize injection rate and hole-to-hole variations in fuel injectors. Using both instantaneous fuel impulse rates and instantaneous mass flow measurements, spray velocity and nozzle flow parameters were evaluated. Several other hole-to-hole resolved injector characterization methods were used to characterize a set of fuel injectors subjected to long term testing. Fuel injector nozzle hole-to-hole variations were found to have a large influence on engine efficiency and emissions. The degree of hole-to-hole variations for an injector has been shown to correlate well with the performance deterioration of that injector. The formation and atomization of fuel sprays, ignition onset and the development of diffusion flames were studied using an optical engine. Flame temperature evaluations have been made using two different methods. NO-formation depends strongly on flame temperature. By applying a NO-formation evaluation method based on both heat release rate and flame and gas temperature it was possible to achieve a reasonable degree of correlation with measured exhaust emissions for very varying operating conditions. The prediction capability of the NO-formation evaluation method was utilized to evaluate spatially and temporally resolved NO-formation from flame temperature distributions. This made it possible to pinpoint areas with a high degree of NO-formation. It was found that small hot zones in the flames can be responsible for a large part of the total amount of NO that is produced, especially in combustion cases where no EGR is used to lower the flame temperature. By applying optical diagnostics methods the combustion and emission formation phenomena encountered during production engine transients were evaluated. The transient strategy of the engine involved reducing the EGR-rate to zero during the initial parts of the transient. Increased general flame temperature and the occurrence of small hot zones were found to explain the increase in NO-emissions during these transients. / QC 20110530

It is well known that high-speed liquid jetting is one of the most powerful techniques available to cut or penetrate material. Recently, it has been conjectured that high-speed liquid jets may be beneficial in improving combustion in such applications as SCRAM jets and direct injection diesel engines. Although there are practical limitations on maximum jet velocity, a fundamental study of the characteristics of high-speed liquid fuel jets and their auto-ignition feasibility is necessary. Important benefits could be increased combustion efficiency and enhanced emission control from improved atomisation. The generation of high-speed liquid jets (water and diesel fuel) in the supersonic to hypersonic ranges by use of a vertical single stage powder gun is described. The effect of the projectile velocity and projectile mass on the jet velocity is found experimentally. Jet exit velocities from a range of different nozzle inner profiles and nozzle hardness are thoroughly examined. The characteristics and behaviour of the high-speed liquid jet and its leading bow shock wave have been studied with the aid of a shadowgraph technique. This provides a clearer picture of each stage of the generation of hypersonic liquid jets. It makes possible the study of hypersonic diesel fuel jet characteristics and their potential for auto-ignition. The fundamental processes by which a supersonic liquid jet is generated by projectile impact have been investigated. The momentum transfer from the projectile to the liquid and the shock wave reflection within the nozzle cavity are the key items of interest. A new one-dimensional analysis has been used in order to simplify this complex and difficult problem. The impact pressure obtained from the projectile was firstly derived. Then, an investigation of the intermittent pressure increase in a closed end cavity and a simple stepped, cross-sectional nozzle were carried out. The nozzle pressure and final jet velocity were estimated and compared to a previous method and to experimental results. Some interesting characteristics found in the experiments relate well to those anticipated by the analysis. The characteristics of a hypersonic diesel fuel jet and its leading edge shock wave were assessed for their potential for auto-ignition using fuel with cetane numbers from 50-100. The investigations were performed at normal ambient air and at elevated air (110 ???C) temperature. So far, there is no sign of auto-ignition that may occur because of the temperature rise of the induced shock.

Thesis (Ph.D.)--Tennessee Technological University, 2007. / Bibliography: leaves 97-102.

Thesis (Ph. D. - Soil, Water, and Environmental Science)--University of Arizona. / Appendix A - Hydrocarbon biodegradation rates and water potential in nitrogen augmented desert soils, by Claudia Walecka-Hutchison and James L. Walworth ; Appendix B - Assessment of C:N ratios and water potential for nitrogen optimization in diesel bioremediation, by Claudia Walecka-Hutchison and James L. Walworth ; Appendix C - Evaluating the effects of gross nitrogen mineralization, immobilization and nitrification on nitrogen fertilizer availability during diesel biodegradation, by Claudia Walecka-Hutchison and James L. Walworth. Includes bibliographical references (leaves 71-82) and appendices.

Thesis (Ph. D.)--University of New South Wales, 2002. / Also available online.

Thesis (M.S.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains ix, 135 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 52-53).

Thesis (M.S.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains x, 97 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 73-74).