Large-Eddy Simulation of Wakes of Waked Wind Turbines

The wake dynamics of a wind turbine are influenced by the atmospheric turbulence and the wake of its upwind turbine. In this work, we investigate the wake characteristics of a waked wind turbine for four different downwind spacings and three different inflows using large-eddy simulation with a turbine parameterized using the actuator surface model. The wake statistics of the waked turbine are compared with those of the stand-alone wind turbine under the same inflow. The results show that the oncoming wake significantly affects the near wake of the waked turbine, where it accelerates the wake recovery by increasing the turbulent convection, and increases the turbulence kinetic energy. The velocity deficit and turbulence kinetic energy in the far wake, on the other hand, are fairly similar with each other for the considered different turbine spacings, and are close to those of the stand-alone wind turbine. As for the wake meandering of the waked wind turbines, it is initiated quickly and enhanced by the oncoming wake turbulence, as shown by the meandering amplitudes and the power spectral density of the instantaneous wake positions. The growth rates of the wake meandering from the waked wind turbines, on the other hand, are close to that of the stand-alone wind turbine, indicating the critical role of the atmospheric turbulence on wake meandering. The present work details how the oncoming wake influences the wake dynamics of the downwind turbine, and provides physical insights on developing engineering models to take into account such effects.

Automated summary

This study investigates the characteristics of the wake of a wind turbine influenced by atmospheric turbulence and the wake of the upwind turbine. The research compares the wake statistics of the influenced turbine with those of a standalone turbine. The results show that the oncoming wake significantly influences the near wake, accelerating wake recovery and increasing turbulence kinetic energy. However, the velocity deficit and turbulence kinetic energy in the far wake are similar across different turbine spacings and comparable to those of the standalone turbine. Additionally, the study shows that the wake meandering of the influenced wind turbines is quickly initiated and enhanced by the oncoming wake turbulence, with similar growth rates to the standalone turbine.