Hi Al,
remarks in red below!!
TJ
In deciding where to put the VGs, I looked at things with the gear up (Photo 1). The gear door has a bump, and there is some gap around the door. Don't know what all this does to BL. Ended up putting VG toward the left side about 26" in font of scoop, and toward the right side right on the gear door bump.
Seeing your gear leg/wheel fairing I am afraid that your BL will be rather though to "repair".
If the impression is not wrong, the wheelfairing alone shadows about 1/2 of the inlet....
Talking about boundary layers:
I fly a AS350B3 for a living, mainly slingload. This particular aircraft came unmodified for slingload.
One necessary mod is the incorporation of a bottom window to see the load. In this case it required to move the landing light ( about 8" diameter with a 45º fairing in the back) to be moved.
Unknowingly the mechanic doing the job moved the light right in front (about 12") of the static ports!!
I was flying 15 to 25 kts faster than the sister-machine without ever catching him!! Took a while to figure this one - but eventually they moved the light out of the way and all is okay...
What has this to do with you? Considering your already narrow intake:
BL is there all right, but generally it should be flowing into the intake.
With the wheel fairing in the way (and as it is, it will produce some vortex at the edge where the tire is visible ....) I predict that you have some rather serious vortex causing trouble at least for half the intake...
I then spent a bunch of time trying to get the pressure measuring tube situated. The only access is through the scoop opening, and I can't get my hands in there; so it is very tough. Plus the tube going in there, or along the surface in front will affect the flow behavior, so what affect are we going to measure. Having multiple measurements would be great; but very difficult to achieve.
a) Just lay the tubes straight back on the outside of the scoop. True it will cause some trouble behind the tube, but at the measuring point it will have clean test conditions. Going straight back it will not cause a lot of disturbance lateral...
b) Considering my concerns above you might want to tuft test the whole area in front f the intake going all the way to the leading edge and one foot beyond the gear lateral.
c) Or you try some oil or soap streak test .....
Taking the wing off (mostly getting it back on because of next to impossible access to nuts), and removing the cooler looks a bit much right now. I realized then; that by putting in a sheet metal 'false' upper duct wall, I could extend it up into the gap at the top (photo 2), thereby changing the shape, and (mostly) closing the gap at the top.
Recommend to to bend like in rev-01. All the way closed you will give away. I would start to keep at least 1/4" off the core in the corner...
The false wall has to be in three parts for the three openings, and there will be gaps between because of the supporting dividers; but it could make a substantial difference. I made the piece for the center, and considered testing just that; but the upper gap concerns me enough that I think I'll try to get all three fit in.
Then go take a flight test. Unfortunately this combines three changes, VGs, closing gap, and changing duct wall. I had hoped to test these one at a time. If there is a substantial change; it will be easy to remove the VGs to see what that effect was.
Of course I'll let you know when I get some results.
Oh, the price of innovation
J.
You are going to miss this once you dialed in!
Al
I am afraid at the end you will have to make the intake narrower (get out of the shadow of the wheel cover) and taller to maintain the intake area. This of course means to redo the intake duct.
Benefit: less BL, no vortex from the wheel cover (if there is one ..... tuft test)
The leg fairings could be tested with VG, turbolator tape, "golf ball" tape, etc. - they are already there tripping some BL, might as well optimize that......
TJ (easy for me to comment, I don't have to do the work! :))
Rusty, sorry (not really ....) for hijacking the RED!!
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