Investigation of dynamic stall models on the aeroelastic responses of a floating offshore wind turbine

Dynamic stall effects significantly affect the aerodynamic load prediction of wind turbines. In order to investigate the dynamic stall effects on the loads and responses of a 15 MW floating offshore wind turbine (FOWT), a novel dynamic stall model, namely IAG, is implemented within the widely-used simulation software package OpenFAST in this study. The superiority and accuracy of the IAG model are verified by comparisons against experimental data and numerical results from the Beddoes-Leishman (B-L) model. The results have shown that the IAG model is able to more accurately capture edges of the hysteresis loops of aerodynamic coefficients corresponding to various airfoils and operation states. The aeroelastic responses of a 15 MW floating offshore wind turbine under normal and extreme environmental conditions are calculated by employing the IAG model. The impact of dynamic stall models on blade loads and displacements has been analyzed. It is found that the B-L model produces larger loads and displacements under high wind speed and yaw error conditions, attributed to the insufficiently computational robustness of the B-L model under deep stall situations and the seriously dynamic stall circumstances. The 1st-order and 2nd-order bending modes of the blade are expected to be enhanced by the aerodynamic loads that are predicted using the B-L model. Consequently, the bending-torsional coupling effects would be enhanced, leading to an increase up to 64.7 % on the in-plane bending moment. This study has confirmed that the dynamic stall model should be properly selected properly for the fully coupled analysis of FOWTs.