Aerodynamic optimization of a propeller airfoil at low Reynolds numbers

Abstract

The aerodynamic optimization method was presented to design a propeller airfoil for a stratosphere airship at low Reynolds numbers. The delta class and shape transformation were adopted to describe the airfoil geometry as the design variables. The flow field was calculated by an open-source code XFOIL to obtain the aerodynamic characteristics as the design targets. The separated particle swarm optimization was employed as the optimization algorithm. The optimization case started with a typical low Reynolds number airfoil E387 and obtained a thicker and more cambered airfoil using the proposed method. The flow fields of the optimized and initial airfoils were analysed by CFD. Results suggested that the lift-to-drag ratio of the optimized airfoil changed from 35.7 to 45.9 with an increasing rate by 28.5% at design cruise condition. The overall aerodynamic performance of the optimized airfoil has been significantly improved at both design and off-design conditions within a wide range of attack angle. The optimization platform presented here is an efficient and effective method for the low-Reynolds-number airfoil designs.