On the Wake Characteristics of the NREL Phase VI Wind Turbine under Turbulent Inflow Conditions

Authors

Islam Hashem - Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China.
Wenliang Ke - Department of Energy and Power Engineering, Xihua University, Chengdu 610039, China
Baoshan Zhu - Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China.

Abstract

Wind turbines often work under turbulent inflow conditions due to the random and the continuously changing wind motion in both time and space. Turbulence affects wind turbines in several ways, including power output, aerodynamic loads, fatigue, wake effects and noise emissions. The wake effect is the biggest challenge when locating downwind turbines in wind farms which imposes large separation distances between individual turbines. In this paper, an overview of the effect of atmospheric turbulence on the wake characteristics of wind turbines is introduced. The reference NREL Phase VI wind turbine was chosen for the present examination. For this purpose, the Lifting Line Free-Vortex Wake (LLFVW) modelling is employed using the Qblade code. This approach relies on a more realistic representation of the wind turbine aerodynamics especially for dynamic wake effects unlike the Blade Element Momentum (BEM) approach which is based on several empirical correction models. The LLFVW results are validated against CFD and NREL/NASA Ames wind tunnel measurements. Ambient turbulence is imposed in the LLFVW simulations with different values of turbulence intensity (TI) ranging from 2% to 15%, which is the typical range for wind turbines.