DESIGN OF OPTIMUM PROPELLERS

Improvements have been made in the equations and computational procedures for design of propellers and wind turbines of maximum efficiency. These eliminate the small angle approximation and some of the light loading approximations prevalent in the classical design theory. An iterative scheme is introduced for accurate calculation of the vortex displacement velocity and the flow angle distribution. Momentum losses due to radial flow can be estimated by either the Prandtl or Goldstein momentum loss function. The methods presented here bring into exact agreement the procedure for design and analysis. Furthermore, the exactness of this agreement makes possible an empirical verification of the Betz condition that a constant-displacement velocity across the wake provides a design of maximum propeller efficiency. A comparison with experimental results is also presented.