Characterisation of a spark ignition system by planar laser-induced fluorescence of OH at high repetition rates and comparison with chemical kinetic calculations

This study reports the application of a novel; high speed laser-detector sy stem for the time-resolved study of flame propagation in a well-controlled spark ignition system. The ignition system allowed full and reproducible co ntrol over the energy deposited during breakdown and the ensuing are discha rge of the spark plasma. Ignition was performed in a closed vessel which wa s filled with stoichiometric mixtures of methane and air, Four sequential s napshots of two-dimensional OH distributions were recorded during single ig nition events by the use of planar laser-induced fluorescence (PLIF), From these OH distributions flame front velocities have been extracted with an a ccuracy of better than 2%. One-dimensional numerical simulations of the ign ition event including detailed chemistry and transport processes have been performed, Experimental results and results from the simulations have been compared to each other with respect to flame front velocities as well as sp atial concentration profiles of OH radicals. In general a good agreement wa s obtained. In this way the ignition system was carefully characterised.