Impacts of dynamic stall on engineering model predictions of wind turbines loads under design load cases

Abstract

The present work is aimed specifically at providing an order of estimate of the load changes due to the inclusion of unsteady aerodynamic effects. Two dynamic stall models are assessed: (1) the incompressible version of the Beddoes-Leishman model and (2) the newly developed IAG dynamic stall model. Two sets of attached flow constants are considered, based on the flat plate approximations according to Jones and the original constants adopted by the IAG model. On top of that, the influence of the impulsive contributions is also highlighted. This work is aimed at filling the gap of the state-of-the-art since at present there is no available study which compares the impacts of using the IAG model against the BL model in real design load case (DLC) scenarios required for wind turbine designs, considering it is very important to estimate loads changes depending on the engineering model being used. It will significantly influence the design of wind turbine structures, especially blades and the strength of the materials for the manufacturing process. Toward the end, providing a proper estimate into the load changes will greatly influence the cost required in blade design and manufacturing. The present study investigates the influence of dynamic stall modeling on the loads acting on wind turbines with various sizes, ranging from 2.5 MW to 8 MW of the rated power. In the studies, both onshore and offshore conditions are considered to obtain the full picture into the engineering modeling effects.