Parametric Study of the Effects of Varying the Airfoil Section, the Chord and Pitch Distributions Along the Propeller Blade

Abstract

The flow through the rotor of a propeller is complex and cannot be solved by pure analytical methods. Varieties of numerical methods were used to handle this problem including the momentum theory, blade element theory, lifting line theory, panel methods and CFD analysis. The objective of this study is to look into the possible use of alternative airfoils (Joukowski and Gottingen) for use in small propellers calculated by a simple validated home-built FORTRAN code based on the momentum theory and blade element theory. This code was then used to investigate the effects of the airfoil section, chord and pitch angle distributions along the blade. The linear pitch distribution in blades of propeller reduced the coefficients of thrust and power and indicated higher blade loading at the intermediate region and lower loading at the tip region in comparison with the Gottingen 796 propeller with the reference pitch distribution. With reference to the two investigated airfoils sections, Gottingen 796 and generalized Joukowski, it was found that the thrust and the power coefficients and the efficiency of the generalized Joukowski propeller are greater than the respective coefficients of Gottingen 796 propeller for advanced ratio J = 0.85 and higher. The predicted results indicated that the use of the elliptical chord distribution instead of tapered blade reduces the blade loading at the tip region and increases it at the intermediate region of the blade, but also reduces the coefficient of thrust, torque and power in comparison with the blade having the reference chord distribution.