Control of pressure increase rate in compression ignition by pulsed plasma irradiation

Homogeneous charge compression ignition (HCCI) engines are potentially high-efficiency, low-polluting alternatives to conventional internal combustion engines. However, the usable operation range of these engines is limited by too rapid combustion for high-load operation. The combustion is brought by the simultaneous ignition over the cylinder volume. An attempt to suppress it has been tried by realizing stratified temperature or fuel distribution in the cylinder. In this paper, the possibility of pulsed dielectric-barrier discharge (DBD) irradiating the air/fuel mixture is discussed as the new stratified ignition method. A rapid compression and expansion machine (RCEM), which can simulate a single engine cycle, was used to investigate it. DBD was generated in the intake tube of the RCEM. The stratified distribution of the irradiated premixture was obtained by the discharge formation at the end of the induction period. By the pulsed DBD method, the rate of pressure increase was decreased and the characteristic oscillation at the top of the pressure waveform was suppressed. These behaviors were confirmed by observation using a high-speed camera. (C) 2015 The Japan Society of Applied Physics