No description available.

No description available.

No description available.

No description available.

Homogeneous charge combustion in a four stroke cycle spark-ignition engine was studied using through-piston-photography with a gated-intensified CCD camera. Analysis of computer stored multiple exposed flame front images was carried out for various engine conditions, in conjunction with the test data and cylinder pressure signals. Representative turbulence scales were inferred from the flame propagation and cylinder pressure data. Fractal analysis of flame edge contours resulted in a fractal dimension D3 in the range 2.12 to 2.23 corroborating data presented elsewhere. A correlation is presented here between the standard deviation of peak cylinder pressure and the fractal dimension D3.

[No abstract available] / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

[No abstract available] / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / [Co-written with Ronald Woodard Klinck] / Graduate

A study of the squish-jet design concept in spark ignition engines, with central ignition, was conducted in a constant volume chamber. The effects of jet size, jet number and jet orientation in generating turbulence and jet enhanced turbulent combustion were investigated. Three sets of configurations with three port sizes were used in this study. The research was carried out in three stages: 1.Qualitative information was obtained from flow visualization experiments via schlieren photography at 1000 frames per second. The flow medium was air. A sequence of frames at specific time intervals were selected to study the results from the respective configurations and jet sizes. The swirling nature of the flow is vivid in the offset arrangement. 2.Pre-ignition pressure and combustion pressure traces were measured with a piezoelectric pressure transducer from which characterising parameters such as maximum pressure, ignition advance and mass burn rate were analysed. Mass fraction curves were calculated using the simple model of fractional pressure rise. A maximum pressure increase of 66% over the reference quiescent combustion case, and combustion duration reduction of 77% were obtained for the offset arrangement with 2 mm diameter port. Comparisons of the times required for 10%, 50% and 90% mass burned are identified and confirmed that it took the 2 mm jet the shortest time to burn 90% of the mixture in the chamber. 3.Two-component velocity measurements were made using an LDV system. Measurements were taken in the central vertical plane of the chamber at specified locations. The data collected were window ensemble- averaged for the mean and fluctuating velocities over a number of cycles. Data intermittency and low data rate precluded, however, cycle-by-cycle analysis. Mean tangential velocities were calculated for each case and the data were used to construct a movie of the tangential velocity as a function of time, suitable for quantitative flow visualization. The vortical nature of the flow was recorded, the distribution being neither solid body rotation nor free vortex, but some complex fluid motion. The jet scale and orientation influence the in generation of turbulence flow field in the chamber, affecting the rate of combustion and the ensuing maximum pressure rise. The offset jet arrangement gives the best results, whereas radially opposed jets have a reduced effect. Increasing the number of jets in opposed arrangement does not enhance turbulent flow. Turbulent flow in the spark region during the onset of ignition was found to be important. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

Includes bibliographical references. / This project involves an investigation of combustion image analysis by the two-colour method as a technique for comparing diesel fuels. The purpose is to master the technique of combustion imaging in both an engine and a Combustion Bomb, with a view to determine the suitability of the two-colour method for fuel comparisons. To evaluate the abilities of the method, an intensive range of testing was conducted on two diesel fuels with slightly different fuel properties.

L’allumage est un point essentiel dans le dimensionnement des moteurs-fusées, et il nécessite de prendre en compte plusieurs phénomènes physiques très distincts qui sont autant de challenges numériques. Le premier point abordé pendant cette thèse est la modélisation et la simulation par Simulation aux Grandes Échelles d’un allumeur de type VINCI. Des gaz chauds, riches en oxygène, sont délivrés de façon supersonique dans une chambre remplie d’hydrogène faisant apparaître un jet fortement sous-détendu et de multiples interactions choc/choc ou choc/flamme. Les premiers instants du processus d’allumage sont ici détaillés. Le second point abordé est la modélisation et la simulation numérique de la combustion H2/O2 à haute pression. En particulier, les effets d’une diffusion non-idéale sont étudiés dans le cas de flammes de prémélange 1D et sur la configuration 2D de type ‘splitter plate’. Un impact de la modélisation sur les espèces produites et le champ de température est ici mis en lumière. / Ignition is a key point in the design of liquid rocket engine (LRE), and it requires to take into account several distinct physical phenomena that constitute numerical challenges. The first point addressed during this thesis is the modeling and simulation using Large Eddy Simulation of a LRE igniter in a configuration close to VINCI rocket engine. The hot gases from the igniter, rich in oxygen, are delivered at supersonic speeds in a chamber filled with hydrogen. Such configuration creates under-expanded jets with multiple shock/shock or shock/flame interactions. A focus is done on the ignition process. The second point addressed is the modeling and simulation of high pressure H2/O2 combustion which occurs. In particular, the effects of non-ideal diffusion are studied through a 1D premixed flames and a 2D splitter plate configuration. An impact of modeling on the species produced and the temperature field is highlighted.