Abstract
Low level jets (LLJs) describe conditions in which the wind speed
reaches a local maximum with respect to altitude near the surface, and
have been observed intermittently in the US Mid-Atlantic offshore
environment. LLJs pose unique operating conditions for future wind
turbines operating in the region, presenting negative shear and locally
strong veer, but they are not typically considered in existing turbine
standards. This work builds upon recent research that explains the
formation and evolution of U.S. Mid-Atlantic LLJs through a simple
analytical governing equation. We generate several LLJ inflow conditions
with varying jet characteristics based on this analytical model and
create monotonically-sheared (MS) analogues with constant veer in order
to assess the impacts of the LLJ on turbine performance and loading.
Using aeroelastic simulations with these inflow conditions on the IEA
15MW reference turbine, we find that the LLJ leads to a greater range of
tower top pitching and yawing moments, which could contribute to larger
accumulated structural fatigue in components compared to
monotonically-sheared inflow. These preliminary results demonstrate a
path toward a unified set of test cases for low-level wind maxima that
can inform International Electrotechnical Commission standards related
to offshore wind turbine design.