A new combustion system for a small direct injection diesel engine has been developed, with a spheroidal cavity and swirl nozzle characterized by weak spray penetration and wide spray angle. This system is intended to realize airborne mixture formation and good combustion processes over wide operating ranges.
In-cylinder observations of the system reveal that droplets are easily bent in the direction of air movement, ignition occurs near the spray tip, and the flame is hard to envelop the spray.
In a single cylinder engine of 460 cm3 swept volume, the system realizes active diffusion burning and mild premixed burning despite of long ignition delay, and provides low fuel consumption and low smoke emission, especially at low speeds.
The above results show a promise to construct a new combustion system, different from conventional combustion systems.