Al,
I think you are
on the right track. The first set of VG's were probably still in the boundary
layer. They won't work unless you are entraining high energy air into the BL.
You could probably tell by using the soap or dirty oil trick to see how
effective they are at mixing the air ahead of the inlet.
Other than a
diverter, or a bleed of some type, I can't come up with any clever soloutions to
solve the boundary layer injestion.
If you want to
just live with the boundary layer injestion and have a purely internal
soloution:
You could try a
mixing vane. It would be just like Ernest's vane except with large ripples in
it. Think of the lobed exhaust mixers on a jet engine. The idea is to
have alternating jets of high and low energy air. This could help
homogenize the flow and with TJ's re-contour stop the seperation
problem.
Monty
Monty; you may
well be right; it may take a combination. However, I did put VGs in front of the
entrance, and it did not make a noticeable difference. They were only
about 8” forward of the entrance because of the gear well that is there. I
think I will try again with them further forward – on the gear door covers; and
make them a bit taller this time.
Al