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echristley wrote:
On Sun, 10 Apr 2005 21:43:53 -0600 Jarrett & Heidi Johnson
<hjjohnson@sasktel.net> wrote.
I've actually done a smiley face induction on a previous model [ I think I modified this current
model to the new profile] but was told that it would work better w/ a more seperate induction with a sorta boundry layer splitter [Picture k of that same report] I didn't totally agree with it at the time on the principle that the boundry layer there is... 0.0001 thick or so.. [ just an un-educated guess] It would be an easy fix to make it w/out the boundry seperator or.. not.. which ever.
You should have went with your first instinct in my opinion. Like you said,
the boundary layer at that point does not exist in any measurable thickness,
and your going to get increased drag from the vortices created in the
intersecting surfaces.
My take was a bit different. Note that there is a 'dam' between the spinner & the intake. The text says that it's there so that the boundary layer can be forced into the inlet. In other words, a brute force method of dealing with the boundary layer.
If you look at a standard Van's cowl & then look at a Sam James cowl or at one of loPresti's cowls, you will see that the aftermarket cowls have 'boundary layer splitters' & Van's does not. The Sam James cowl is faster than Van's.
Even more significant to me in that paper are the exit techniques. Both the extractor bump & the 'internal cowl flap' look like they deserve attention.
Charlie
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