Still documenting it...
Basically creates a vortex by injecting moderate pressure air around the outer edge in a spiral.
Exhaust is at the center, through a spark arrestor. Ashes and smoke are trapped by the vortex and re-burn, producing a clean exhaust.
Once up to operating temperature, produces zero smoke and ash.
Provided you don't overload it (about 2/3rd full), it produces zero sparks. If you do overload it, it looks a lot like an afterburner.. :)