Thread: Discussion boundary layer thickness
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Old Sep 29, 2012, 01:14 PM
kcaldwel is offline
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Joined Jan 2007
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First, why are you worried about the boundary layer thickness? EDFs routinely ingest the boundary layer from long inlet tubes, so I don't think that is a big issue. Total separation at high AoA is quite possible in the area you show. That might cause some vibration?

The boundary layer thickness depends on how far back from the front of the body you are (l), how fast it is flying, a small dependency on altitude, and whether the flow is laminar or turbulent.

On a flat plate in laminar flow:

d (thickness) = 5.20* l/(Rl)^1/2

Rl = Re at that length

For turbulent boundary layer on a flat plate:

D= 0.37*l/(Rl)^0.2

Here l = length of plate since the beginning of transition.

With those chines, the safest approach wold be to assume turbulent flow from the nose, and just use the turbulent thickness calculation. I can calculate that thickness for you if you give me a distance and a speed estimate.

Kevin
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