I think scoolbubba is referring to both fan and hi temp parts of the engine cowlings.
I'm not sure how much aero engineering went into it- other than aesthetic design. You would likely know though. Happy New Years!
How much aero engineering? TONS. They're much like the "lobed mixers" you see on some smaller engines (they've been around since the 60s), only lighter for a similar aerodynamic benefit.
What do they do? They allow the flow on one side of the plate to mix with the flow on the other side of the plate by creating a pair of vortices. The inside of the plate has a higher pressure, the outside lower. Think of it like a mini-version of the wing. One side has high pressure (bottom) and the other side has lower pressure (top). The vortices force the two concentric flows to mix more rapidly. This has several benefits: 1) Noise abatement... depending on magnitude of the relative speeds, noise caused by two flows of dissimilar speeds scales by the third or the
eighth power. The sooner you get the two flows moving together, the better. 2) Propulsive efficiency... the mixing makes the fan more efficient... I don't have a quick figure to put that in perspective, but think of it this way: if you're not wasting energy on noise, where does it go? 3) It does look cool, doesn't it?
Think I'm full of it? Search for "lobed mixer" on google scholar.
OK, back to my nerd hole.
PS: if you don't like efficiency for Al Gore and Bambi (the deer, not the stripper who has all your $1 bills), like it for the extra legs, heavier gear, or most $$-payin' pax you can have now. Don't thank the nerds, it's their job.
