Status of the Special-Purpose Airfoil Families

This report describes work sponsored by the U.S. Department of Energy (DOE) under Contract No. DE-AC02- 83CH10093. The work is directed at developing thin and thick airfoil families, for rotors with diameters of 10 to 30 m, that enhance annual energy output at low to medium wind speeds and provide more consistent operating characteristics with lower fatigue loads at high wind speeds. Performanceis enhanced through the use of laminar flow, while more consistent rotor operating characteristics at high wind speeds are achieved by tailoring the airfoil such that the maximum lift coefficient Cl,max is largely independent of roughness effects. Using the Eppler airfoil design code, two thin and one thick airfoil family were designed; each family had a root, outboard, and tip airfoil.Two-dimensional wind-tunnel tests were conducted to verify the predicted performance characteristics for both a thin and thick outboard airfoil from these families. Atmospheric tests on full-scale wind turbines will complete the verification process.