I think that you should pursue one
problem at a time until you have exhausted the chance of any improvement on
that front.
You have too many variables and you
are not eliminating any in these tests. You are merely making unknown possible improvements/detriments
to lots of problems all at once.
Monty;
I’m with you all the way on this. I’ll
admit to trying the easy first to see if good things would happen; but no such
luck. Not to make excuses; but . .one of the downsides of this wing root
installation is that its accessibility sucks . .er.. is not at all good.
Taking the wing off to remove the cooler is not an easy undertaking; and even
then; with the scoop and fairing on, you can’t get at it. It slides in
and out end-wise; so clearance (read leakage gaps) is needed. So I do need to
get better data, and do whatever I can do toward determining a fix before
opening things up to make changes.
One of the things I hadn’t quite
figured was how to seal things up without major dismantling. So about
this “gorilla snot” (gees; there’s got to be a more household
term for that) – that may be the ticket. Do you know what happens
to it when it gets hot – like over 200F? Will it stay in place; and will
it harden and make it impossible to ever get the cooler out without a jackhammer?
Is this a Home Depot item – or do I have to know someone in the trade?
Thanks,
Al
From what I can tell, you should be
getting more static pressure at the core than you are even with the BL problem
and the wall being a non-ideal shape (as you stated). This could be due to
leakage, or it could be due to separation and duct stall due to the boundary
layer ingestion problem. There is no way to know for sure with the info you
have.
I am not convinced by the 9 in of
water 5/8 from the surface that you should get 6 in at the cooler face. Absent
a methodical rake test from the wing out to below the scoop, and
all along the front of the scoop it is impossible to make much of
conclusion from one point of data. What is it at .25 in from the surface, along
the entire length? If 1/4 of your duct has slow boundary layer air going into
it (which unfortunately is the poorly contoured surface of the duct) you may
have a disaster for flow inside the duct. If the flow separates from the top
wall, the unseparated high energy flow will not diffuse properly. What is
happening at the end of the duct towards the wheel well? All unknown variables.
First order of business is eliminate
ANY chance of leakage past the cooler. Eliminate this variable first. This
includes the area near the tanks where there is no core, only tubes. This
should be sealed up completely as well as the perimeter of the core. Then
retest with no other changes. Make sure you use the same location for your
manometer and use foam around the end of the tube. That way your data will be
apples to apples.
Once armed with this info you can
proceed to the next step. If it were me, I would fix the duct contour (no
gaps in the metal allowed) and then retest. Then I think I
would try a mixing divider vane in the inlet before the change
in curvature. That way the high energy air is mixed with the low energy
air BEFORE it has to begin diffusion. If this fails I would move
on to sealing the gear door and external VGs
Forget about quick fixes and start
killing rats until you find the one causing the majority of the problem. Right
now you are only "wounding" or perhaps missing "the" rat
all together while flailing at them with a big blunt instrument. Get out the
rifle and kill them (verifiably, unquestionably dead) one by one
until the problem is solved. ;-)