Spark plug and corona abilities to ignite stoichiometric and lean methane/air mixtures

In this work, spark plug and corona discharge of 3-20 ms in duration have been used for ignition of stoichiometric and lean fuel methane/air mixtures. Comparison of spark plug and corona ignition abilities shows that corona discharge allows more efficient ignition with less discharge energy. It is proved experimentally that corona ignition provides faster combustion due to larger discharge volume, generation of turbulence around the discharge electrodes promoting combustion and assistance to the flame front propagation through the combustion chamber. In our experimental conditions corona allows ignition and flame propagation regime in quiescent extremely lean fuel mixture of equivalence ratio 0.52 that cannot be realized using more powerful spark.