Ignition of high pressure lean H2:air mixtures along the multiple channels of nanosecond surface discharge

The initiation of combustion of lean H2:air mixtures, ER=0.5--0.6, by nanosecond surface dielectric barrier discharge (nSDBD) was studied experimentally at high initial pressures, P=3--6 bar. The discharge was studied in different gas mixtures for the pressure range 1-12 bar. The ignition was initiated by two different discharge modes: streamer or filamentary nSDBD. The influence of the discharge structure and energy deposition on the ignition was demonstrated. Three regimes of multi-point ignition were observed: ignition with a few kernels, quasi-uniform ignition along the edge of the high voltage electrode and ignition along the plasma channels. The velocities of flame propagation were analyzed. The minimum ignition energy of the discharge and ignition delay time of combustion have been measured and analyzed with the help of kinetic numerical modeling.