Experimental Study of Multipoint Ignition in Methane–Air Mixtures by Pulsed Microwave Power

Microwave plasma offers a promising method to achieve faster combustion in internal combustion engine. In this paper, microwave multipoint ignition was confirmed via the high-speed imaging technique. The experiment was conducted with microwave resonant ignition system and optical system. A 2-ms, 3000-W, 2.45-GHz pulsed microwave power was used as energy source to produce initial flame kernel in combustion chamber. High-speed imaging was used to record the ignition characteristics via high-speed camera. Ignition experiments were conducted at high pressure of 2 bars of stoichiometric methane-air mixtures. It can be observed in the image and the pressure curves that multiple flame kernels are generated simultaneously. Faster combustion speed is achieved by pulsed microwave power ignition than traditional spark plug ignition in constant volume chamber.