No description available.

No description available.

No description available.

The work reported in this thesis was conducted to study the effects of variable valve actuation on combustion, emissions, and fuel economy in a modern design of 4-valve per cylinder SI engine. The use of statistically-based procedures for the design of experiments allowed a limited number of tests to be used to explore a wide region of each of the experimental variables. A series of steady-flow tests was conducted to assess the effects of valve lift on flow past the valves and the nature of any in-cylinder motion generated. Results from the former were incorporated into a filling and emptying model that allowed levels of trapped residuals and pumping work to be estimated for different valve strategies. The in-cylinder motion tests explored asymmetric valve lifts, that is to say where the two valves were opened by a different amount. These results allowed a pair of response surfaces to be established to model the intensity of both axial and barrel swirl within the cylinder over the range of valve lifts. Engine tests were conducted in two parts. The first explored the effects of changes in exhaust event phasing, intake event phasing, intake event duration, and peak intake valve lift. The design of the experiment allowed linear, quadratic, and interactions between the variables to be modelled using regression analysis. Statistical analysis allowed the most influential factors (both main effects and interactions) to be identified. Contour plots of the modelled response were used to draw conclusions about the nature of the response surface and to isolate the effects of valve opening and closure angles as well as overlap. The results were correlated with those from the steady-flow tests and from the computer model. The strategy for the second phase of tests was chosen after considering the previous results. The steady-flow tests indicated that there was considerable potential for enhancing in-cylinder motion by adopting a valve deactivation strategy and combining it with a low lift of the active intake valve. The second phase investigated the use of such a technique in conjunction with large overlaps over a range of duration of the intake valve event. The results from both phases of engine tests indicated possible strategies to reduce emissions from future engines.

No description available.

No description available.

Initial fire spread is composed of the processes of ignition, flame spread, and burning rate. The effects of a material's thermal characteristics and burning behaviors on flame spread are important. However, many zone and field models of compartment fire can not predict spread on objects accurately enough due to the neglect of these behaviors in their fire growth sub-models. As a result, a model dedicated to the early stage of fire growth is needed to provide the accuracy necessary for competent assessment of the response of safety systems, as well as satisfying the requirement for a comprehensive risk assessment. This study is undertaken to investigate the use of formulations outlined by previous researchers by review of the theory of flame spread models. A computer model is proposed that can determine the impact of the material properties with emphasis on practical engineering analyses. Through this computer program, we can obtain the pyrolysis zone, the flame height, the burnout time, the burnout portion, the mass loss rate, total heat release rate, and mean flame velocity of a material at specific time. The effort in this study has been focused on developing a relatively simple model for fire spread on a vertically oriented material which contains the most common aspect of fire growth theory such as the transit burning rate, material properties, burner affection, flame spread rate and burnout. This study used Vc++ as a program development platform which has an easy to use interface and reasonable execution times. The model is a combination of two sub-models. One is to simulate the flame spread on horizontal surface. The other is to simulate it on a vertical surface. In two sub-models, the spread process model is two-dimensioned yet symmetric. By using empirical physical equations and correlations, this model predicted flame spread by solving a set of closed coupled correlations simultaneously. Each sub-model contains several functions: ignition, mass loss rate calculation, burning area and the surface temperature calculation. The results of this proposed computer model are compared with experimental studies involving a limited number of comparisons of experimental data for early stage vertical flame spread. The model calculations and experimental measurements of the mass loss rate, heat release rate, and radiation flux were found to be in good agreement. Recommendations are made for further development of the more complex initial stage fire growth model.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1968. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: self-heating; smoldering ignition; plywood; bowes. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1969. / Typescript. Vita. Description based on print version record. Includes bibliographical references.