Quantifying impacts of shell augmentation on power output of airborne wind energy system at elevated heights

This work presents an in-depth design analysis of full-scale airborne wind energy systems. The prime focus is to quantify the impact of an airfoil-based shell carrying a 3-bladed rotor tailored to airborne needs. A high-fidelity numerical approach is used to gain insights into the design's performance by solving the numerical model of the resulting system. Three-dimensional simulations are carried out for a range of wind speeds and tip speed ratios to evaluate the aerodynamic behavior of the shell rotor by lifting the complete shell rotor assembly at elevated heights. The sensitiveness of the performance is rigorously analyzed in terms of the power coefficient (C-p,C-s), thrust coefficient, blockage effect, swallowed mass flow and bound circulation. An important finding highlights that the shell configuration is more efficient under optimal flow conditions in augmenting the power output. Besides, the augmented effects of the shell significantly contribute to the resulting Cp; s to outperform the Betz limit. Meanwhile, the net extracted power of the proposed design is 66% higher than that of the bare rotor. Finally, the simulation results suggest that the shell rotor operating close to the higher tip speed ratios behaves quite similar to that of the bare rotor configuration. (C) 2021 Elsevier Ltd. All rights reserved.