I don't think this design would help with a CPU cooling fan. There's a reason they went from planes to water, and I think that same reason would apply even more

I don't think this design would help with a CPU cooling fan. There's a reason they went from planes to water, and I think that same reason would apply even more so for a CPU fan. If you're going to spend the space, simply use a bigger fan at lower RPMs. Electric fans for homes are a more interesting question. I was going to suggest that a Vorando or Dyson already has a lot of elements of this, and gives more bang for the buck, but I think the two could be combined. A Vornado-style fan really reduces vortex shedding, but probably has some turbulence internally. A modified prop design could reduce that a lot.