Comparison of ignition and early flame propagation in methane/air mixtures using nanosecond repetitively pulsed discharge and inductive ignition in a pre-chamber setup under engine relevant conditions

An optically accessible pre-chamber setup was used to investigate the ignition occurrence and early flame propagation in methane/air mixtures at density conditions relevant engine application. Two Schlieren setups coupled with fast recording cameras allowed visualization of combustion chamber a close up location, respectively. A spectroscopy-based diagnostic simultaneously applied characterize mixture composition near spark plug. Nanosecond Repetitively Pulsed Discharge (NRPD) different pulse patterns terms number repetition frequency applied. Conventional inductive NRPD-assisted were compared for first time engine-relevant conditions. The effect air fuel ratios assessed both laminar turbulent Results showed that discharge dynamics strongly affects effectiveness event consequently later stages, suggesting path an optimization NRPD control parameters based on specific case. is shown be advantageous stable especially lean due increased local concentration radicals provided by multiple discharges. This suggests use gives advantage onset diluted where there low mixing level reduced turbulence. simultaneous application spectral techniques gaining fundamental understanding processes involved gas mixtures, useful validate simulations ultimately predicting controlling such systems practical applications.