Integration of airfoil stall and compressibility models into a propeller blade element model

Abstract

The blade element method is an indispensible engineering design tool. It executes rapidly on a personal computer and is capable of accurate propeller performance predictions. An extensive literature survey reveals that for conventional high-aspect ratio propeller blades lifting surface and computational fluid dynamics approaches add a large degree of complexity without providing significantly improved performance prediction capabilities as compared to the blade element/vortex theory. The accuracy of the blade element method is, however, highly dependent on the fidelity of the airfoil aerodynamic model. The primary focus of this paper is on presenting a nonlinear aerodynamic model of airfoils that can be used in combination with the blade element method for enhanced propeller performance prediction over a wide range of advance ratios. The proposed nonlinear airfoil model includes effects of angles of attack up to 90 degrees and compressibility corrections. Results of this method are validated against experimental measurements. Excellent agreement between experiment and prediction is shown for subsonic helical tip Mach numbers.