Multi-Point Ignition Process induced by Microwave DischargeMulti-Point Ignition Process induced by Microwave Discharge

microwave plasma is a promising technology to produce faster combustion in internal combustion engine1. In this study, multi-point ignition and spatial ignition induced by microwave discharge had been confirmed via high-speed schlieren imaging method. The experiment was conducted with the microwave resonant ignition system and the schlieren optical system. 2ms-3000W-2.45GHz microwave pulse was employed as the ignition energy source to produce initial flame kernel in the combustion chamber. The reflective schlieren imaging method was used to illustrate the flame development process with a high speed camera. A quartz glass coated with indium tin oxide (ITO), which ensured the sufficient microwave reflection characteristics and light transmission respectively2, was used as the bottom of the microwave resonant chamber. Ignition experiments were conducted at high pressure of 2 bars of stoichiometric methane-air mixtures. It can be observed in schlieren images that flame kernels were generated at more than one location simultaneously and flame propagated with different speeds in the combustion chamber. And the reason of multi-point ignition was also studied and confirmed.