Burning Speeds, Flame Kernel Formation and Flame Structure of Bio-jet and JP8 Fuels at High Temperatures and Pressures

Fundamental concepts of laminar flames have been studied both experimentally and theoretically. Topics such as, thermodynamic properties of gases at high temperatures, plasma formation in argon and air, flame kernel development, flame structure, burning speed of jet fuels such as ethanol, JP-8 and biomass based fuel have been studied.;The formation and propagation process of flame were studied in detail by a new model. Three important parameters affecting the formation and propagation of flame are: electrical discharged energy, chemical energy and energy transfer to the gas and electrodes. The roles of these parameters were studied and fundamental properties of laminar flames like laminar burning speed were measured at constant temperatures and pressures. As a part of this study the thermodynamic properties of inert gases including oxygen, nitrogen, air, argon and helium were measured at extremely high temperatures. These properties were necessary for the model developed for plasma and flame kernel growth.;Laminar burning speeds of jet fuels (JP-8) and their biomass based alternatives which were R-8 (POSF 5469) and ethanol are measured at high temperatures (500-650 K) and pressures (1-7 atm). The experiments were carried out in two constant volume spherical and cylindrical vessels. The laminar burning speeds of these fuels were compared with each other and also with results of other researchers. Flame structure of premixed spherical flames was studied in shadowgraph optical system and an advanced Planar Laser Induced Fluorescence (PLIF) system.;Flame structure study includes cell instability analyses, cell formation, and profile of OH molecule within the flame. The effect of different diluents like argon and helium were investigated at several temperatures and pressures. One of the main goals was to achieve laminar flames at higher pressures. The important parameters which were investigated were pressure, temperature, equivalence ratio, flame thickness, diluent type and stretch factor.;Introduction of a new experimental set up which is an advanced Planar Laser Induced Fluorescence (PLIF) system: Installation, design, and operation of this system are one of important objectives of this thesis. This system is used for combustion diagnostics and flame behavior study. The details of PLIF system will be descried in chapter 1 (introduction).