Campfires.. Many campgrounds have gone to these new "Safety" Fire pits consisting of two metal rings with about 4" of concrete between them.. No way (at least easily) to dig ounder 'em and they are often "Spiked" in so you can't easily lift em to let air into the fire pit.....
Muffler shop bent a piece of pipe From the outlet end a short run the UP the height of the fire pit and a bit. then back to the horozontial run then down and then a bit more than up for six inhches to a foot.
On the "Cold" end of the pipe I mounted a small "Computer" type fan runs on a 12 volt "Jump Pack" battery.. Blows air in nicely. Big fire..