Comment on wes-2023-7

Abstract

<strong class="journal-contentHeaderColor">Abstract.</strong> Wake characteristics and aerodynamics of a balloon wind turbine were numerically investigated for different wind scenarios. Large eddy simulation, along with the actuator disk model, was employed to predict the wake behavior of the turbine. To improve the accuracy of simulation results, a structured grid was generated and refined by using an algorithm to resolve about 80 % of the local turbulent kinetic energy in the wake. Results contribute to designing an optimized layout of wind farms and stability analysis of such systems. The capabilities of the hybrid ADM-LES model when using the mesh generation algorithm were evaluated against the experimental data on a smaller wind turbine. The assessment revealed a good agreement between numerical and experimental results. While a weakened rotor wake was observed at a distance of 22.5 diameters downstream of the balloon turbine, the balloon wake disappeared at about 0.6 of that distance in all wind scenarios. Vortices generated by the rotor and balloon started to being merged at a tilt angle of 10&deg;, which intensifies the turbulence intensity at 10 diameters downstream of the turbine for wind speeds of 7 m s^-1 and 10 m s^-1. By increasing the tilt angle, the lift force on the wings experiences a sharper increase with respect to that of the whole balloon, which signifies a controlling system requirement for balancing such extra lift force.