Enhancement of laminar flow across an airfoil by PLFC

[MJOGRADY25]

SEPARATION/DESTRUCTION OF THE BOUNDRY LAYER AT LOW SPEEDS AND HIGH ANGLE OF ATTACK CAN BE INHIBITED AND DELAYED BY SEVERAL TECHNIQUES.

ONE OF THESE IS VACUUM-INDUCED FLOW THROUGH THE PERFORATED SURFACE OF THE AIRFOIL WING.--ironicly called '\" positive laminar flow control"

THIS WAS INVESTIGATED BEFORE AND AFTER WWII BY THE USA,BRITAIN,& LUFTWAFFE, NASA, MS STATE UNIV AE DEPT.

IT WAS ABANDONED FOR SAFETY REASONS

I HAVE A POTENTIAL APPLICATION, SAFE, FOR GROUND VEHICLES.

DOES ANYONE HAVE ANY EXPERIENCE, REFERENCE OR KNOWLEDGE IN THIS MATTER?

 

[btrueblood]

1. Please don't "shout", turn off your capital letters.

2. "IT WAS ABANDONED FOR SAFETY REASONS"

No, it was abandoned because the amount of energy needed, and the weight added to the airframe, were not offset by the added lift or reduced drag. Since low-speed, high-AOA conditions are usually seen during landing, it is easier/lighter to create a variable geometry wing using flaps & slats, etc. than to blow/suck on the wing surfaces.

You seem to have a handle on the sources for studies of boundary layer control. I have some limited experience with the subject matter, but would point you to the NASA server and then to a university library that has an aeronautical engineering department for further research.

 

[KENAT]

While I was there, University of Southampton was doing some research on this as I recall. Either in the aeronautical department or possibly ISVR.

As well as the problems btrue gives, another one was that the holes tend to get blocked by dirt, insects etc.

One supposes this may be worse for a ground vehicle on anything more than a one off land speed record type effort.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

http://eng-tips.com/market.cfm?

 

[gruidae]

There was research done, using an A5(A3J)Vigilante with many small perforations on the upper surface of the wing to draw air in using engine driven pump(s). These tests proved the concept - lowered drag and increased lift across a wide range of speed/aoa conditions. I have searched the web and find no references but a more thorough search of NASA sites might yield something (I believe it was NASA that was conducting the research). The Vigilante was used because of its advanced wing design (quite efficient for the time) so there was undoubtedly a lot of data available.

 

[berkshire]

MJOGRADY25 (Mechanical)
Do a search for

August Raspet and Boundary Layer Research at Mississippi State

Mis State did a lot of research on this in the 70's

B.E.