Study on boundary conditions of k-ε-fp turbulence model for wind turbine wake simulation

ABSTRACT

Wind turbine wake has a great impact on the power output and fatigue damage of the whole wind farm. As a result, wind turbine wake simulation has attracted attention from both researchers and engineers for decades, in which turbulence modeling is the key point. Among all the turbulence modeling methods for wind turbine wake, $k-\epsilon -f_P$, a RANS model proposed by Laan in 2015, can balance well between efficiency and accuracy. In the current research, the boundary conditions of $k-\epsilon -f_P$ turbulence model have been studied comprehensively. It was found that the boundary conditions of the model are affected by the wind conditions of the actual wind turbine, resulting in poor simulation accuracy under high wind shear conditions. Five simulation cases have been carried and compared with field measurement results. It was found that the roughness length $z_0$ is the most important factor for the determination of boundary conditions. Considering the wind shear conditions around wind turbine rotor, a new determination method for roughness length $z_0$ of the ground has been constructed, which corrects the wind profile prediction under high wind shear conditions. This research will contribute to the micro-sitting of future large wind farms.

KEYWORDS:

• Wind turbine wake
• RANS
• turbulence model
• boundary conditions

Acknowledgements

This work has been supported by the scientific research project of China Three Gorges Renewables (Group) Co., Ltd. “Research on Technical and Economic Evaluation of the Wake Effect of Plateau Wind Farm Group” (Contract No.: 63010037). And this work is supported by the National Natural Science Foundation of China project “Study on fluid-structure interaction of wind turbine blade with large deformation based on elastic actuator line model” (NSFC 52006071). This work is also supported by supported by the Fundamental Research Funds for the Central Universities(2020MS022). This work is supported by the National Key Research and Development Program of China (Project number: 2019YFE0104800).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The work was supported by the National Natural Science Foundation of China [NSFC 52006071]; Scientific Research Project of China Three Gorges Renewables (Group) Co., Ltd. ”Research on Technical and Economic Evaluation of the Wake Effect of Plateau Wind Farm Group” [Contract No.: 63010037]; Fundamental Research Funds for the Central Universities [2020MS022]; the National Key Research and Development Program of China (Project number: 2019YFE0104800).