A method to realize multipoint ignition with microwave plasma

Summary form only given. Multipoint ignition system offers a higher combustion velocity, which can lead to higher energy efficiency and less heat loss by conduction. By now, there are only two ways of multipoint ignition, laser ignition and multi-spark plug ignition. And unluckily, they are both difficult to be put into practical use. In this paper, a method to realize multipoint ignition is introduced. To imitate the gasoline engine, the experiment was done in a cylindrical microwave resonator with the inner size of 93mm*9.5mm. Several needles, which could lead to the multipoint discharge by the electric field distortion, were planted in it. Theoretical and simulation analysis were done and the result demonstrated the feasibility of this method. And a primary experiment was conducted in the resonator premixed with methane and air. A direct view of multipoint discharge was recorded by a high speed camera. The three flashes show that a three-points-igniting system was realized. And the time-resolved pressure data shows that this method can increase the max pressure by 5% and shortened the rise time (from the moment ignite to the moment reach the max pressure) by 15%, compared to the spark ignition system. That means this multipoint ignition system can offer a higher efficiency and lower emissions.