In the photos below of KC-135R Stratotankers you can see that their CFM-56 engines have what appears to be some sort of exhaust port in the cowling, near the intake along the bottom side area.
What are these exhaust ports used for? Do they have something to do with the ductwork for the intake heating pipes?
Also, are CFM-56 engines simply the military version of the same engines used on some civilian airliners? They look a lot like Pratt & Whitney 4000 turbofans.
If they are the same engines (both military & civilian), why do only the military versions have these exhaust ports in their cowlings? I've never seen these holes in the side of airliner's engines.
Photo © Gerhard Plomitzer
Photo © Tony Zeljeznjak
Photo © Lauri Huima
Photo © Stevis