High-Order Large-Eddy Simulations of a Wind Turbine in Ducted and Open-Rotor Configurations

TL;DR

This study uses high-order large-eddy simulations to compare ducted and open-rotor wind turbines, revealing that ducted turbines generally produce more power and are less affected by yaw angles, with flow dynamics influenced by the duct.

Contribution

It provides detailed simulation-based insights into the performance differences and flow characteristics of ducted versus open-rotor turbines across various operating conditions.

Findings

Ducted turbines have higher power output than open-rotor turbines.

Ducts enhance flow turbulence and blade vortex structures.

Ducted turbines are less sensitive to yaw angle variations.

Abstract

High-order large-eddy simulations are performed to study the performance and flow field of a ducted wind turbine operating at different tip speed ratios. To evaluate the effects of the duct, simulations with the same tip speed ratios are also performed on the corresponding open-rotor turbine. It is found that the ducted turbine consistently obtains higher power outputs than the open-rotor counterpart, and the duct itself enhances flow turbulence and blade trailing-edge vortices but weakens tip and hub vortices. Flow bifurcation is observed at the largest tip speed ratio and is identified to be caused by blade blockage effects. Comparative simulations are also performed on both turbines under different yaw angles. It is noticed that the ducted configuration is insensitive to small yaw angles and maintains higher power outputs than the open-rotor configuration at all yaw angles. Moreover, it is observed that the wakes of both configurations recover more quickly as the yaw angle increases.