Hydrogen and methane plasma assisted ignition by NS discharge behind reflected shock wave

Abstract

The kinetics of ignition in lean H 2 :O 2 :Ar and CH 4 :O 2 :Ar mixtures has been studied experimentally and numerically after a high-voltage nanosecond discharge. The ignition delay time behind a reflected shock wave was measured with and without the discharge when detecting OH* radiation. It was shown that the initiation of the discharge with a specific deposited energy of 10 – 30 mJ/cm3 leads to an order of magnitude decrease in the ignition delay time. Discharge processes and following chain chemical reactions with energy release were simulated. The generation of atoms, radicals and excited and charged particles was numerically simulated using the measured time - resolved discharge current and electric field in the discharge phase. The calculated densities of the active particles were used as input data to simulate plasma-assisted ignition. Good agreement was obtained between the calculated ignition delay times and the experimental data. It was shown that ignition delay time is difficult to measure in too lean mixtures. Possible approaches to solve this problem were discussed.