I have an outer pipe and an inner pipe a lot smaller than the inside of the the outer pipe, and the head of the (mini) turbine will be connected to a metal rod. There will be wires connected to the head and it will be turning to the wind. How should I set up the wires?
A slip ring connector is the usual way to solve this problem. The electrical contact is made by fixed brushes which make sliding contact with a rotating ring.
The key point is to ensure that you maintain a good and consistent electrical contact. It is common to use brass slip rings and graphite contactors held in place with springs and designed to wear and be replaced periodically.
Graphite has the advantage that it combines good electrical conductivity with self lubrication and is soft enough to wear to conform precisely to the shape of the surface of the slip ring.
It is also important that the enclosure is designed to prevent contamination of the contact surface by dust, oil, moisture etc.