Among wind energy research, wind turbines with more than one rotor have recently gained a lot of attraction. Apart from promised lower maintenance- or construction costs, an increase in power generation per area, a better control over their wake (wind shadow/turbulence from turbines) makes these turbines highly attractive for large scale usage. This study shows experimentally, how the wake in a dual rotor can be steered and why this is highly promising for increasing windfarm efficiencies.

Most human activity happens in the layer of the atmosphere which extends a few hundred meters to a couple of kilometers above the surface of the Earth. The flow in this layer is turbulent. Turbulence impacts wind power production and turbine lifespan. Optimizing wind turbine performance requires understanding how turbulence affects both wind turbine efficiency and reliability. This paper points to gaps in our knowledge that need to be addressed to effectively utilize wind resources.

Two major aircraft measurement campaigns above the North Sea provide insights into modifications of the wind field and sea surface induced by wind farms: The aircraft performed transects at hub height upstream and downstream of wind farm clusters, and identified different effects, e.g., how long it takes for the wind speed to recover after the wind farm, how changes across the coastline interact with wind energy, and if wind farms are well represented in numerical simulations.

Various simulation tools exist to provide load forecasts in the wind energy field (engineering models and numerical simulations). A newly introduced concept is the center of wind pressure, a quantity extracted from a wind field. In previous works, similar behaviour, then the main shaft bending moments, was shown. However, a clear relationship is missing. In this work, this gap is filled through the introduction of a calibration parameter.

High-fidelity fluid-structure coupled simulations of the IEA 15 MW rotor under storm and yaw misalignment shows that certain misalignments trigger strong edgewise vibrations. Growth surges when effective power turns positive near −35° and fades near −43° yaw. Single-blade analysis finds lock-in at −37° with large tip motion and stability at −60° due to off-resonant Strouhal shedding. It is concluded that aeroelastic response is inflow-specific and operational mitigation strategies are needed.