Henry,
On Thu, Dec 31, 2015 at 3:15 PM, Henry Spencer <hspencer@xxxxxxxxxxxxx>
wrote:
On Thu, 31 Dec 2015, Jonathan Goff wrote:
Duct cooling is also an interesting approach worth considering for high
lifetime engines. Basic idea is you put a very thin-wall cylindrical
sleeve
inside the straight part of the combustion chamber with a thin gap between
it and the chamber wall. You run your film coolant behind that duct...
Interesting idea -- is there a good reference for it?
Also, if you need an even flow distributed across the face, a foam-like
surface might not be your only approach.
Yeah, if you're willing to use what's essentially 3D printing (which,
contrary to popular misconception, is not entirely a recent development) to
make the wall, or at least the innermost layer, you can avoid many of the
problems of foam/mesh materials by having detailed control of the fine
structure of the material.
(Although there are simpler things that can help: one trick P&W came up
with in some exotic-propellant work was to use Rigimesh as the inner wall
but put much of the pressure drop in feed orifices behind it, minimizing
the impact of the flow uncertainties in the Rigimesh.)