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