The allison 250 uses more of a swirl (similar to the airflow produced by a propeller) than a toroidal vortex. Actually it uses two of them in opposite directions
If you click on this link and scroll down to the third set of pictures you will see an Allison 250 combustion liner with a very basic explanation of the swirl.
The combustion chamber
Then inner ring of baffles (pressed flat flaps in the right hand picture) blow air in a counter clockwise (as you look at it) direction and the outer ring blows in a clockwise direction. This swirling primary air causes good mixing with the fuel for burning, it also shapes the flame and with the help of the secondary airflow, keeps it central in the chamber. 25% of airflow is used in the primary area (the holes on top in the left hand picture) 72% passes through the holes around the outside of the liner for cooling and to keep the flame away from the walls of the liner and the final 3% passes along the outside