We all strive to have the fiercer, hotter burns possible, in order to achieve the best burn efficiency. And the idea of letting the fire out of the riser, which for most of us happens during the bad portions of a burn. You trod a somewhat beaten path with this single vortex. Peter has tried it, and some others too, nearly the way you have implemented it this time. You'll have to sniff in the old posts at Donkey's.
If you really want to make your fire turn one direction. I'd say, go the cyclonic route. A J tube entry, round if possible, finishing into a neutral vane into a big burn chamber, even better if it's conical, like a cyclone.
http://billpentz.com/woodworking/cyclone/cyclone_mods.php#CycloneFixes
Been there, done that, and i can tell you the fire gets hot and turns a lot. (
Pics of the cyclonic thingy0)
Thought, it would may be better to do it with a batch and neutral vane, so you could overload it.
Two overloading examples of a batch.