Verification and validation of an actuator disc model

Abstract

Wind turbine wake can be studied in computational fluid dynamics with the use of permeable body forces (e.g. actuator disc, line and surface). This paper presents a general flexible method to redistribute wind turbine blade forces as permeable body forces in a computational domain. The method can take any kind of shape discretization, determine the intersectional elements with the computational grid and use the size of these elements to redistribute proportionally the forces. This method can potentially reduce the need for mesh refinement in the region surrounding the rotor and, therefore, also reduce the computational cost of large wind farm wake simulations. The special case of the actuator disc is successfully validated with an analytical solution for heavily loaded turbines and with a full‐rotor computation in computational fluid dynamics. Copyright © 2013 John Wiley & Sons, Ltd.

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. In the present work, the implementation of Réthoré et al [13] is used, which can be summarized as:…”

“…Troldborg [23] found that for modern large wind turbines with a sharp tip, c2 should be set to 27, which will be adopted in the present research. Réthoré et al [13] validated the AD with tabulated airfoil data with full rotor computations of a single NREL 5-MW reference wind turbine. Reasonable agreement was found, however, the AD with tabulated airfoil data overpredicted the tangential forces, which resulted into an overpredicted power.…”

“…Instead, the rotor forces are modeled with an actuator disk (AD) [7,12,13]. The AD acts as a momentum sink in the Navier-Stokes equations.…”

“…The wind turbine geometry is not physically modeled, instead the rotor forces are represented by an Actuator Disk (AD) [7,12,13]. The AD acts as a momentum source term in the Navier-Stokes equations.…”

How does turbulence change approaching a rotor?

“…The wind turbine rotor is modeled as an actuator disk (AD) using the implementation proposed by Réthoré et al (2014 use the same model to simulate the induction zone of a 500 kW turbine and validated their predictions with lidar measurements. …”