Energy is extracted from a free stream fluid flow of wind or {HEAD ~ water} by {TAIL ~ means} of a multi turn helicoid structure with a relatively small pitch angle 
by
Energy is extracted from a free stream fluid flow of wind or { HEAD ~ water } by { TAIL ~ means } of a multi turn helicoid structure with a relatively small pitch angle
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH