Abstract
Abstract. Advanced aeroelastically optimized tip extensions are among rotor innovation concepts which could contribute to the higher performance and lower cost of wind turbines. A novel design optimization framework for wind turbine blade tip extensions based on surrogate aeroelastic modeling is presented. An academic wind turbine is modeled in an aeroelastic code equipped with a near-wake aerodynamic module, and tip extensions with complex shapes are parametrized using 11 design variables. The design space is explored via full aeroelastic simulations in extreme turbulence, and a surrogate model is fitted to the data. Direct optimization is performed based on the surrogate model seeking to maximize the power of the retrofitted turbine within the ultimate load constraints. The presented optimized design achieves a load-neutral gain of up to 6 % in annual energy production. Its performance is further evaluated in detail by means of the near-wake model used for the generation of the surrogate model and compared with a higher-fidelity aerodynamic module comprising a hybrid filament-particle-mesh vortex method with a lifting-line implementation. A good agreement between the solvers is obtained at low turbulence levels, while differences in predicted power and flapwise blade root bending moment grow with increasing turbulence intensity.
Highlights
The trend of reducing the levelized cost of energy (LCOE) of horizontal axis wind turbines through increasing rotor size has long been established
Its performance is further evaluated in detail by means of the near-wake model used for the generation of the surrogate model and compared with a higher-fidelity aerodynamic module comprising a hybrid filament-particlemesh vortex method with a lifting-line implementation
The surrogate-based optimization (SBO) framework is set up based on the MATLAB code package MATSuMoTo (Müller, 2013, 2014), which is the MATLAB Surrogate Model Toolbox for deterministic, computationally expensive black-box global optimization problems with continuous, integer, or mixed-integer variables that are formulated as minimization problems
Summary
The trend of reducing the levelized cost of energy (LCOE) of horizontal axis wind turbines through increasing rotor size has long been established. The existing bibliography relevant to wind turbine applications typically focuses on winglets and aerodynamic tip shapes purely from an aerodynamics point of view (Johansen, 2006; Gaunaa, 2007; Ferrer, 2007; Chattot, 2009; Elfarra, 2014; Farhan, 2019; Matheswaran, 2019). Exceptions to this general trend are the recent articles (Zahle, 2018; Sessarego, 2018; Hansen, 2018; Rosemeier, 2020; Horcas, 2020) that put the focus on general blade tip designs and aeroelastic performance. −3 3 and prebend, which are typically not used in a traditional blade design
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