Ignition Performance of Pulsed Microwave-Assisted Sparks in Lean Methane/Air Mixture

In this work, a microwave-assisted spark ignition was investigated for premixed lean methane/air mixtures. Experiments were performed in a combustion chamber with a constant volume. The initial pressure of the chamber was set to 0.1MPa and 1Mpa. Equivalence ratio Ø was varied from 0.51 to 0.6 to investigate the ignition behavior near the lean limit. High temperature regions in flames were visualized by the Schlieren photography using a high speed video camera. When the irradiation delay of microwave is 200 μs and the pulse frequency is 10 kHz, the probability of ignition reached maximum. A microwave irradiation to the mixture enable to ignite the mixture of equivalence ratio of 0.52.