I also came across these profiles (NREL S822 and S823) when researching airfoils specific to wind power generation. I think the article (
http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=212729) was highly relevant also. The full pdf should also be available at some point from
http://www.cprl.ars.usda.gov/REMM_Publications.htm. These airfoil profiles were designed specifically for small wind turbines (1KW - 10KW) back in 1993. My understanding is that now both Southwest Windpower Skystream (
http://www.windenergy.com) and Endurance Windpower (
http://www.endurancewindpower.com) are using them in their blade designs. When made from wood, though, I can understand that they would significantly increase manufacturing complexity. I'm hoping to only have to make one from wood which I will then use as a plug for a fiberglass mold.
I'm building wind turbines in Kabul, Afghanistan with the eventual goal of encouraging a small sustainable wind power industry (our project was instrumental 20 years ago in developing the micro-hydro industry here - arguably much better suited to the country than wind, sure). We have a wind map now, though, and the improved power profile these airfoils offer may make a significant difference to the utilization of wind here.
Could anyone help me determine what would be an optimal chord width and pitch angle? I am hoping to basically duplicate the blades from the article mentioned above. They were 1.67m long and produced maximum power of 1.5KW. The S823, thicker airfoil, is used for the root section, up to 40%, while the S822 is used for the remaining blade section. According to the article they had a linear chord taper, and "a near Glauert twist distribution" (I haven't been able to find out what this means!). Any help would be greatly appreciated and certainly help speed things up for us (I am admittedly a real novice with these aerodynamic issues).
Thanks in advance,
Carl Larson
RESAP Engineer, IAM