VORTEX GENERATOR EXTENDS LEAN LIMIT.

Flame speed and lean extinction limit of a single-cylinder engine have been experimentally extended via installation of a ″vortex generator″ in the intake. This consists of a nest of delta wings which generates a vortex system in the inlet air flow. Results indicate that this vortex generator should ideally be of variable geometry and replace the conventional throttle. This could be achieved by placing two vortex generators of low blockage ratio, one on top of the other, and rotating one with respect to the other to change blockage ratio. The effect of the vortex generator is particularly beneficial in the lean mixture range.