Corona-Ignition vs. Spark Ignition: A Fundamental Comparison for varying thermodynamic conditions of modern turbocharged Gasoline Engines

Combustion strategies of modern gasoline engines make high demands on a robust ignition process to enable a further optimization of the engine performance. During the last years RFcorona-ignition gained increasingly attention for gasoline engine applications. By means of a voluminous radical-chemical inflammation, the corona-ignition allows a stable combustion process with strongly reduced cycle to cycle fluctuations.
This contribution compares a corona-initiated flame with a combustion initiated by a spark ignition system, driven by a high energy coil, for various engine conditions within the operation map of modern turbocharged gasoline engines. Primary aspects are the influence of charge motion, dilution rate, engine load and speed, and the compression ratio. Emphasis is put upon the comparison of the principal system characteristics and their fundamental differences. The measurements presented were carried out on single cylinder research engines as well as multi-cylinder engine prototypes, based on current series engine geometries.

The results display the fundamental differences between the thermally initiated pointwise spark ignition and the radical based spacious corona ignition process, leading to different dependencies on the key engine parameter.