Methods for root effects, tip effects and extending the angle of attack range to ± 180 deg., with application to aerodynamics for blades on wind turbines and propellers

For wind turbine and propeller performance calculations aerodynamic data, valid for several radial stations along the blade, are used. For wind turbines the data must be valid for the 360 degree angle of attack range. The reason is that all kinds of abnormal conditions must be analysed especially during the design of the turbine. Frequently aerodynamic data are available from wind tunnel tests where the angle of attack range is from say -5 to +20 degrees. This report describes a method to extend such data to be valid for ± 180 degrees. Previously the extension of data has been very approximate following the whim of the moment with the analyst. Furthermore, the Himmelskamp effect at the root and tip effects are treated in the complete method.