Re: L1011 engine No 2

Date:         05 Oct 99 03:14:39 
From:         David Lednicer <dave@amiwest.com>
Organization: Analytical Methods, Inc.
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The fairing you are looking at is called a "Frisbee Fairing", named
after its developer.  The fairing is designed to eliminate a flow
separation that occured in that area and in doing so, it reduces the
noise in the aft cabin.  It was originally only fitted to L1011-500s.

	The separation that it eliminates is caused by the relatively thick
boundary layer on the fuselage encountering a region of increasing
(adverse) pressure in front of the "pylon" below the #2 engine inlet.
Without the fairing, the adverse pressure gradient would be too steep
for the boundary layer to stay attached and it would separate, forming a
necklace vortex around the "pylon".  The fairing makes the gradient less
steep and eliminates the separation and associated vortex.

-------------------------------------------------------------------
David Lednicer             | "Applied Computational Fluid Dynamics"
Analytical Methods, Inc.   |   email:   dave@amiwest.com
2133 152nd Ave NE          |   tel:     (206) 643-9090
Redmond, WA  98052  USA    |   fax:     (206) 746-1299