This Is AuburnElectronic Theses and Dissertations

Optimum Propeller Design for Electric UAVs

Date

2012-05-16

Author

Wall, David

Type of Degree

thesis

Department

Aerospace Engineering

Abstract

A propeller behaves as a rotating wing producing lift in the direction of the axis of rotation. Many previous propeller optimization methods have been developed, but usually focus on piston or turboprop applications. This study discusses the more fundamental propeller theories and uses a hybrid blade element momentum theory to model the propellers. A brushless motor model is developed and coupled with the propeller theory in an optimizer. Two single point optimizations are made, one for a climb condition and the other for a cruise condition. A third optimization is presented with optimization at climb and cruise conditions. The optimizations are conducted with a hybrid pattern/search particle swarm optimizer. The airfoils for the propellers are optimized with the same optimizer and a simplex method. Multiple objective functions are evaluated for each of the conditions. One having non-dimensional values and another with dimensional values. Dimensional values prove to provide better results for all of the conditions. The optimized cruise propellers display smaller chords, higher pitches, and larger diameters while the optimized climb propellers have larger chords, lower pitches and smaller diameters. The multipoint optimization yields higher pitches with chords and diameters between the single point optimizations. All optimized propellers show improvement over comparable baseline propellers.