Exploratory optimizations of propeller blades for a high-altitude pseudo-satelitte

Nine optimization rounds were conducted in the current work with as objective to maximize the efficiency of a propeller for a High Altitude Pseudo-Satellite. In these optimizations, the blade element method based on airfoil performance calculation by XFoil and 2D RANS are used. All rounds tend to maximize the propeller diameter and provide maximum chord values in 60-80% span range with lower chord values at the propeller root and tip. Thinner blades with larger chord are obtained after including the thickness distribution as an optimization parameter and also by increasing the number of blades. Next, a comparison of the blade element method and three-dimensional RANS simulations is done on a reference four-bladed single rotation propeller. The overall performance in terms of thrust and power as well as the local pressure and skin friction coefficients for a sample blade section (85 %-radius) are analyzed to gain insight into the loss of accuracy when using low-fidelity blade element methods compared to a high-fidelity simulation.