Comparison of different fidelity aerodynamic solvers on the IEA 10 MW turbine including novel tip extension geometries

Abstract

Lifting-line based solvers could supersede the blade element momentum (BEM) method as the industry standard in the near future as rotor sizes of modern wind turbines and computational resources continue to increase. A comparison study between both methods is presented where the IEA 10 MW wind turbine is evaluated in the aero-servo-elastic simulation tool QBlade, comparing the lifting-line free vortex wake method to an unsteady blade element momentum solver. Besides the baseline rotor of the IEA 10 MW turbine, the comparison includes several blade tip extensions, including a swept and a dihedral geometry, to further differentiate capabilities between both methods in aerodynamically complex flow fields. As a reference serve results from equivalent simulations performed with multiple fidelity solvers of the simulation tool HAWC2. Results of a rigid load case demonstrate considerable improvement regarding the aerodynamic accuracy of lifting-line based methods in below rated conditions over BEM codes. The aerodynamic loads on geometrically complex tip extensions in steady conditions prove good capabilities of lower fidelity codes to predict out-of-plane bend shapes but also clear limitations regarding loads on swept geometries. A quasi-steady aeroelastic load case further demonstrates the capability of both QBlade codes to produce comparable results to similar fidelity solvers of the HAWC2 tool on an integral level. A detailed comparison in the time domain shows a larger dependency of the results on the type of structural solver that is used in contrast to the fidelity level of the aerodynamic method.