Predictive capability of actuator disk models for wakes of different wind turbine designs

Abstract

To evaluate the predictive capability of the actuator disk (AD) models in simulating wakes of different wind turbine designs, we compare the results of the AD simulation with those of the actuator surface (AS) simulation for the EOLOS, NREL and a variant of the NREL (i.e., NREL-V) wind turbine designs. Two types of AD models are considered, i.e., the AD-R and AD-NR models corresponding to the AD model with and without rotational effects, respectively. For the AD models, the force coefficients are both obtained from the corresponding AS simulations. The results from the AD simulation are compared with those of AS simulations. It is observed that the velocity profiles predicted by the AD models agree well with the AS predictions. For the turbulent kinetic energy and the Reynolds shear stress, differences appear at far wake locations (7D, and 9D downwind of the turbine where D is the rotor diameter) for both the EOLOS and the NREL-V turbines. In case of the NREL turbine, on the other hand, there is an overall good agreement except in 3D downwind to the turbine. Furthermore, the modes obtained by using the proper orthogonal decomposition from the AD and AS simulations are also presented and compared with each other, indicating that the distribution of the mode energy, and the location and features of the mode patterns differ for different turbine designs.