Numerical Modeling of Wind Turbine Wakes

Abstract

An aerodynamical model for studying three-dimensional flow fields about wind turbine rotors is presented. The developed algorithm combines a three-dimensional Navier-Stokes solver with a so-called actuator line technique in which the loading is distributed along lines representing the blade forces. The loading is determined iteratively using a blade-element approach and tabulated airfoil data. Computations are carried out for a 500 kW Nordtank wind turbine equipped with three LM19.1 blades. The computed power production is found to be in good agreement with measurements. The computations give detailed information about basic features of wind turbine wakes, including distributions of interference factors and vortex structures. The model serves in particular to analyze and verify the validity of the basic assumptions employed in the simple engineering models.

Thek-ε-fPmodel applied to double wind turbine wakes using different actuator disk force methods

“…This method is based on blade element momentum theory and it is introduced by Sørensen and Shen [20] for the actuator line technique. In later work, the method is used for AD simulations by El Kasmi and Masson [8], Réthoré et al [13], Wu and Porté-Agel [17] and others.…”

Simulation of wind turbine wakes using the actuator line technique

“…The AL imposes body forces distributed along rotating lines representing the aerodynamic loads of the wind turbine blades (see [10,33] for details). The body forces imposed in the Navier-Stokes equations are calculated through a coupling with the Flex5 code.…”

“…In this way, it is not necessary to make a detailed mesh for the rotor geometry, and the mesh points can be devoted to coping with the turbulence characteristics in the wake. This technique, referred to as the actuator line (AL) technique, was originally developed by Sørensen & Shen [10] and later implemented in a general aeroelastic simulation tool [11] and Troldborg [12]. The AL technique combines a three-dimensional NavierStokes solver with a technique in which body forces are distributed radially along each of the rotor blades.…”

Instantaneous Response and Mutual Interaction between Wind Turbine and Flow

“…In the present work the flow is modelled using Ellipsys3D to perform LES. The turbines are modelled with the actuator line method, see Sørensen and Shen [14]. The actuator lines are fully coupled to the aero-elastic code Flex5, see Øye [15]).…”