Spark initiation of propane - air mixtures near the minimum ignition energy.

Flame kernel growth from a spark in propane-air mixtures at 1 atm. is studied in a constant volume bomb with a high speed (10,000 fps) laser schlieren system. The spark current and voltage waveforms of an inductive ignition source are simultaneously recorded with the photographic recordings. The temporal growth of the measured equivalent kernel radii is investigated at conditions near the minimum ignition energy. The investigations show the existence of a critical radius and the influence of the critical radius on kernel growth. A model is developed to simulate the flame kernel growth observed in the experiment. The model initially incorporates a blast wave over a short negligible time followed by a growing diffusion boundary layer and an electrical power input. The growth of the diffusion boundary layer is formulated by an integral approach involving the temperature dependence of the overall reaction kinetics. The model predictions are compared with the experimental data.Ph.D.Mechanical engineeringAutomotive engineeringChemical engineeringUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/162213/1/8920565.pd