The wake wrecker: a special case of a shallow low-level jet simulation impacting a turbine in WRF-LES

Analysis of nacelle-based lidar measurements of the inflow of a 6-MW floating wind turbine suggests the presence of low-level jets (LLJs) with noses below turbine hub height. Since the occurrence of these events is significant, we use the ability of the Weather Research and Forecasting (WRF) model to perform large-eddy simulations (LESs) in an attempt to reproduce the inflow conditions observed under a rather shallow and pronounced LLJ event. We also use a generalized actuator disk to model a turbine within WRF-LES, and analyze and explore the differences and similarities between the characteristics of the wake simulations and wake measurements that were also performed on the nacelle of the turbine but with a scanning lidar during the LLJ event. The analysis of the simulations reveal both that under the strong wind shear and veer conditions of the LLJ event, the wake shows a wrecking behavior and that these type of scanning lidar wake measurements might be insufficient to characterize the wake when a shallow and narrow LLJ directly impacts the wake of a large wind turbine rotor.