Advance drag reduction technique

Hi everyone,
I'm doing a research on advance drag reduction technique that are being used or have the potential use on aircraft. Would anyone know any useful sites or books about this ?!
Thanks heaps
Andy

 

[OLDspectre]

Check out some of the kitplane magazines. Some designs are quite advanced. Barnaby Wainfan's "Wind Tunnel" series of articles often deal with pracical drag reduction.
Burt Rutan's designs are almost an education in drag reduction. The Questair Venture is a totally different approach, reducing wetted area and using long, high aspect ratio wings.
LoPresti makes many items for reducing drag on existing planes.
Fin type vortex generators are commonly used on lightplanes
Air flow is an incredibly complicated area of study where what sounds logical doesn't always work, and theoretically ideal designs using laminar flow or supercritical airfoils may create dangerously unstable designs.

 

[airtabman]

Wheeler type VGs (as used in Airtabs - see

http://www.airtab.com)

are better than vane type VGs as they only need to be .25 to .3 times the height of the boundary layer to have an effect.
contact me if you want more info (shawn.coyle@airtab.com)

 

Advanced in what sense? There are many means by which drag may be reduced depending upon the application. For high lift where separation is an issue, pressure drag is the main problem, and here vortex generators work. Check out some work done by DERA (now QinetiQ). I think there is a paper by Hackett and co-workers on the 10th international symposium on laser applicationsin fluid mechanics. Wheeler type devices are not always better, it depends upon the spacing of the VVGs, and whether they are co- or counter-rotating. Synthetic jets are also being considered for this purpose (work of many including myself (Crook) and Glezer). For attached flow, drag reduction means reducing skin-friction which means shaping to keep the flow laminar or advanced techniques such as riblets, polymer addition, spanwise wall oscillation. The list is endless. Vortex generators are not advanced. The CTR at Stanford (where I work) are doing some work on drag reduction using polymers. Another technique is to use plasma to control boundary layer turbulence and reduce drag.

Hope this helps. For good reviews and papers, check out JFM, Physics of Fluids, Annual Review of Fluid Mechanics, Progress in Aerospace Sciences, AIAA Journal and Journal of Aircraft, and the Aeronautical Journal (RAeS). There are also plenty of books out there. You may want to check out the book by Gad-el-Hak and visit his website.

 

[laro]

hi,
for reduction of induced drag you may want to visit

http://www.winggrid.ch

where new non-classical concepts are exposed.