Abstract
Abstract. When a wind turbine is yawed, the shape of the wake changes and a curled wake profile is generated. The curled wake has drawn a lot of interest because of its aerodynamic complexity and applicability to wind farm controls. The main mechanism for the creation of the curled wake has been identified in the literature as a collection of vortices that are shed from the rotor plane when the turbine is yawed. This work extends that idea by using aerodynamic concepts to develop a control-oriented model for the curled wake based on approximations to the Navier–Stokes equations. The model is tested and compared to time-averaged results from large-eddy simulations using actuator disk and line models. The model is able to capture the curling mechanism for a turbine under uniform inflow and in the case of a neutral atmospheric boundary layer. The model is then incorporated to the FLOw Redirection and Induction in Steady State (FLORIS) framework and provides good agreement with power predictions for cases with two and three turbines in a row.
Highlights
A curled wake is a phenomenon observed in the wake of a wind turbine when the turbine is yawed relative to the freestream velocity
A new model has been proposed to study the aerodynamics of the curled wake
The model solves a linearized version of the Navier–Stokes momentum equation with the curl effect added as a collection of vortices with an elliptic distribution shed from the rotor plane
Summary
A curled wake is a phenomenon observed in the wake of a wind turbine when the turbine is yawed relative to the freestream velocity. The curled wake mechanism, in the context of wind turbine wakes, was first identified by Howland et al (2016) during a porous disk experiment, and in LESs using an actuator disk model (ADM) and actuator line model (ALM) This mechanism was described by a pair of counter-rotating vortices that are shed from the top and bottom of the rotor when the rotor is yawed. Fleming et al (2017) show that the generated vortices affect the performance of wake steering and motivate the development of engineering models (like the one in this paper), which include wake curling physics Controllers based on such models would pursue different, and likely more effective, wind farm control strategies. The model is tested and compared to LESs using actuator disk and line models
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