Wind Farm Structural Response and Wake Dynamics for an Evolving Stable Boundary Layer: Computational and Experimental Comparisons

Abstract. The wind turbine design process requires performing thousands of simulations for a wide range of inflow and control conditions. This necessitates computationally efficient yet time-accurate models, especially when considering wind farm settings. To this end, FAST.Farm is a dynamic wake meandering-based midfidelity engineering tool developed by the National Renewable Energy Laboratory targeted at accurately and efficiently predicting wind turbine power production and structural loading in wind farm settings, including wake interactions between turbines. This work is an extension to a study into constructing a diurnal cycle evolution based on experimental data. Here, this inflow is used to validate the turbine structural and wake meandering response between experimental data, FAST.Farm simulation results, and high-fidelity large-eddy simulation results from coupled SOWFA-OpenFAST. The validation occurs within the nocturnal stable boundary layer when corresponding meteorological and turbine data were available. To that end, load results from FAST.Farm and SOWFA-OpenFAST are compared to multi-turbine measurements from a subset of a full-scale wind farm. Computational predictions of blade-root and tower-base bending loads are compared to 10-minute statistics of strain gauge measurements during 3.5 hour of the evolving stable boundary layer, generally with good agreement. This time period coincided with an active wake steering campaign of an upstream turbine, resulting in time-varying yaw positions of all turbines. Wake meandering was also compared between the computational solutions, generally with excellent agreement. Simulations were based on the use of a high-fidelity precursor constructed from inflow measurements and using state-of-the-art mesoscale-to-microscale coupling.