Abstract
Actuator disc and actuator line techniques are widely used for modelling wind turbines operating in wind farms. These techniques essentially replace the blade geometry with applied body forces, which reduce the resolved length scales significantly and hence the required grid resolution. This work is a verification of the coupling between the flow solver EllipSys3D and the aeroelastic tool Flex5, through a quantitative comparison of coupled actuator line, coupled actuator disc, and standalone Flex5. Steady state performance predictions, instantaneous reaction to turbulence and damage equivalent load analyses all show a very good agreement between the three methods. Differences can be explained primarily by the higher fidelity modelling of the coupled simulations; this is particularly in regard to the influence of blade flexibility, as the actuators deflect and interact with the modelled flow. Additionally, some overpredictions of loading at the blade tip and root below rated velocity for the actuator methods can be attributed to the Gaussian smearing used to apply the body forces.
Highlights
The effective planning of large wind farms requires accurate and reliable numerical tools to both assess the achievable power output and predict component fatigue
This work is a verification of the coupling between the flow solver EllipSys3D and the aeroelastic tool Flex5, through a quantitative comparison of coupled actuator line, coupled actuator disc, and standalone Flex5
The actuator disc (AD) method distributes the forces over the entire rotor swept area, and the influence of the blades is modelled as an integrated quantity in the azimuthal direction
Summary
The effective planning of large wind farms requires accurate and reliable numerical tools to both assess the achievable power output and predict component fatigue. The turbine wakes are highly turbulent including large scale motions, e.g. wake meandering, which has been shown to cause a noticeable increase in the fatigue loading of subsequent turbines [1]. Investigating these time-varying effects requires turbulence resolving numerical simulations which can adequately capture important wake structures. Reducing the required grid resolution can be achieved using actuator disc (AD) or actuator line (AL) techniques to replace the actual turbine blade geometry with applied body forces, and is widely used in Large Eddy Simulation (LES) to study wakes and wind farm flows [2,3,4].
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call