Interactional Aerodynamics Analysis of a Multirotor Energy Kite

Abstract

Airborne wind energy (AWE) technology aspires to provide increased options for wind energy harvesting at a lower cost than conventional turbines. As AWE technology is still in its infancy, there is relatively little published information concerning its aerodynamic details. In this study, we apply the FLOWUnsteady suite of aerodynamic analysis tools—including a vortex particle method for wakes and actuator line methods for rotors and wings—to the analysis of a fixed‐wing, on‐board generation, wind harvesting aircraft (or windcraft for short). Specifically, we explore variations in the rotation directions and vertical and horizontal (front to back) spacing of the rotors to understand the complex interactional aerodynamics of a multirotor windcraft design. Our results indicate that for the configurations presented herein, the rotor‐on‐rotor and wing‐on‐rotor interactions induce maximum total variations on cumulative rotor performance of less than 3% relative to baseline, with most configurations varying from baseline by 2% or less. In addition, rotor‐on‐wing interactions cause decreases in wing lift coefficient of up to roughly 7% (for the configurations simulated) relative to the isolated wing. Furthermore, through selecting specific rotor rotation directions, it is possible to prescribe a portion of the shape of the wing lift distribution. Further exploration, perhaps with the assistance of optimization techniques, may yield greater insights into this uncharted space of windcraft interactional aerodynamics.