Preprints
https://doi.org/10.5194/wes-2022-106
https://doi.org/10.5194/wes-2022-106
 
21 Nov 2022
21 Nov 2022
Status: this preprint is currently under review for the journal WES.

Actuator line model using simplified force calculation methods

Gonzalo Pablo Navarro Diaz1, Alejandro Daniel Otero2,4, Henrik Asmuth1, Jens Nørkær Sørensen3, and Stefan Ivanell1 Gonzalo Pablo Navarro Diaz et al.
  • 1Uppsala University, Wind Energy Section, Campus Gotland, Visby, Sweden
  • 2Universidad de Buenos Aires, Facultad de Ingeniería, Buenos Aires, Argentina
  • 3Technical University of Denmark
  • 4Computational Simulation Center (CSC-CONICET), Buenos Aires, Argentina

Abstract. To simulate transient wind turbine wake interaction problems using limited wind turbine data, two new variants of the actuator line technique are proposed in which the rotor blade forces are computed locally using generic load data. The proposed models, which are extensions of the actuator disc force models proposed by Navarro Diaz et al. (2019a) and Sørensen et al. (2020), only demand thrust and power coefficients and the tip speed ratio as input parameters. In the paper it is shown the analogy between the Actuator Disc Method (ADM) and the Actuator Line Method (ALM) and from this derive a simple methodology to implement local forces in the ALM without the need for knowledge of blade geometry and local airfoil data. Two simplified variants of ALMs are proposed, an analytical one based on Sørensen et al. (2020) and a numerical one based on Navarro Diaz et al. (2019a). The proposed models are compared to the ADM, using analogous data, as well as to the classical ALM based on blade element theory, which provides more detailed force distributions by using airfoil data. To evaluate the local force calculation, the analysis of a partial wake interaction case between two wind turbines is carried out for an uniform laminar inflow and for a turbulent neutral atmospheric boundary layer inflow. The computations are performed using the Large Eddy Simulation facility in OpenFOAM, including SOWFA libraries and the reference NREL 5MW wind turbine as test case. In the single turbine case, computed normal and tangential force distributions along the blade showed a very good agreement between the employed models. The two new ALMs exhibited the same distribution as the ALM based on geometry and airfoil data, with minor differences due to the particular tip correction needed in the ALM. For the challenging partially impacted wake case, the analytical and numerical approaches manage both to correctly capture the force distribution at the different regions of the rotor area, with, however, a consistent overestimation of the normal force outside the wake and an underestimation inside the wake. The analytical approach shows a slightly better performance in wake impact cases compared to the numerical one. As expected, the ALMs gave a much more detailed prediction of the higher frequency power output fluctuations than the ADM. These promising findings open the possibility to simulate commercial wind farms in transient inflows using ALM, without having to get access to actual wind turbine and airfoil data, which in most cases are restricted due to confidentiality.

Gonzalo Pablo Navarro Diaz et al.

Status: open (until 06 Jan 2023)

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Gonzalo Pablo Navarro Diaz et al.

Gonzalo Pablo Navarro Diaz et al.

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Short summary
In this manuscript, the capacity to simulate transient wind turbine wake interaction problems using limited wind turbine data has been extended. The key novelty is the creation of two new variants of the actuator line technique in which the rotor blade forces are computed locally using generic load data. The analysis covers a partial wake interaction case between two wind turbines for a uniform laminar inflow and for a turbulent neutral atmospheric boundary layer inflow.