Electrohydrodynamic Ignition System for S.I. Engines

This article reports on the effects of various types of high field electrical phenomena imposed on low load lean combustion in a spark ignition petrol engine. The first part of the work deals with purely electrical field effects with no induced ionization. An electric field was applied via an insulated static high voltage DC electrode (up to 15 kv) which does induce excess charge effects, near the spark source. This was found to have very modest effects on the imep and its cyclic variability, which are unlikely to be significant enough to warrant commercial development.

Further work reported here concerns the testing of an electrohydrodynamic device formed from a modified spark plug. This was operated in a test chamber under typical pre-combustion pressures where it was possible to obtain corona flows up to 10 m/s. Measurements of the response time of this system showed that it is entirely feasible to establish a fully developed corona ‘wind’, rapidly enough to be of potential value during the ignition phase at a spark ignition engine, in marked contrast to the insulated electrode system.