The things on the end could be stabilizers of some sort for slipstream or transwarp travel.
I see those coils as helping to smoothen the transition from slipstream, warp, transwarp, and/or normal space, or to make sure the slipstream window and/or transwarp conduit closes without causing any damage/disturbance to normal space, or vice versa.
WTF? Are you spying on me? I had just now decided that that is exactly what they're for!
When those rings are spinning, I'd imagine they make quite a fuss as they whip and churn and in that manner fold space into a frothy lather to achieve their warp effect.