Since Update 2.2, ARC Turbines spawn in almost every session on Buried City, Riven Tides, Blue Gate and Spaceport, so any of those four maps is now a reliable Turbine hunt. Dam Battlegrounds is the one to skip: Embark removed Turbines from its standard sessions entirely.
That matters because the Turbine is the only known source of Turbine Compressors (per the community wiki), a part several Amplified weapon upgrades need. Before 2.2, many sessions on those maps only had a chance of a Turbine, which made farming a gamble. Checked against Embark's 2.2.0 notes (20 October) and its earlier Turbine patch notes.
The ARC Turbine is a flying ARC machine Embark added with the Riven Tides update on 28 April. Embark describes it as calm and docile while it drifts across the Rust Belt, until someone interferes, at which point its defences turn "brutal".
Embark's notes give the maps, not exact spawn points, and the Turbine moves around once it's in the air. Pick the map that suits your loadout and the rest of your run.
Embark's patch notes explain most of the fight, and its 25 September Frozen Trail developer Q&A (as summarised by a fan hub) adds tactics. A few specifics come from the community wiki, labelled as such below.
