Athanasios Barlas

Aeroelastic Optimization of a 10 MW Wind Turbine Blade with Active Trailing Edge Flaps

This article presents the aeroelastic optimization of a 10MW wind turbine ’smart blade’ equipped with active trailing edge flaps. The multi-disciplinary wind turbine analysis and optimization tool HawtOpt2 is utilized, which is based on the open-source framework OpenMDAO. The tool interfaces to several state-of-the art simulation codes, allowing for a wide variety of problem formulations and combinations of models. A simultaneous aerodynamic and structural optimization of a 10 MW wind turbine rotor is carried out with respect to material layups and outer shape. Active trailing edge flaps are integrated in the design taking into account their achieved fatigue load reduction. The optimized ’smart blade’ design is compared to an aeroelastically optimized design with no flaps and the baseline design.

Extreme load alleviation using industrial implementation of active trailing edge flaps in a full design load basis

The application of active trailing edge flaps in an industrial oriented implementation is evaluated in terms of capability of alleviating design extreme loads. A flap system with basic control functionality is implemented and tested in a realistic full Design Load Basis (DLB) for the DTU 10MW Reference Wind Turbine (RWT) model and for an upscaled rotor version in DTU’s aeroelastic code HAWC2. The flap system implementation shows considerable potential in reducing extreme loads in components of interest including the blades, main bearing and tower top, with no influence on fatigue loads and power performance. In addition, an individual flap controller for fatigue load reduction in above rated power conditions is also implemented and integrated in the general controller architecture. The system is shown to be a technology enabler for rotor upscaling, by combining extreme and fatigue load reduction.

Computational fluid dynamics-based surrogate optimization of a wind turbine blade tip extension for maximising energy production

This article presents a design study into the redesign of a wind turbine blade tip seeking to increase the energy production subject to the loads constraints of the existing blade. The blade shape is parameterized to allow for planform changes in the tip region with respect to chord, twist and blade length extension, and additionally three parameters that allow to explore winglet-like shapes. The design strategy uses 3D computational fluid dynamics computations of the geometrically resolved rotor to create a surrogate model, after which the tip shape is numerically optimized based on the surrogate model, subject to a number of geometric and loads-based constraints. The study shows that it is possible to increase power production by 2.6% for a blade extension with a winglet, without increasing the flapwise bending moment at 90% radius, whereas for a straight blade extension it was only possible to achieve an increase of 0.76%.

Optimization of morphing flaps based on fluid structure interaction modeling

(07/12/2018) Optimization of morphing flaps based on fluid structure interaction modeling This article describes the design optimization of morphing trailing edge flaps for wind turbines with ‘smart blades’. A high fidelity Fluid Structure Interaction (FSI) simulation framework is utilized, comprised of 2D Finite Element Analysis (FEA) and Computational Fluid Dynamics (CFD) models. A coupled aero-structural simulation of a 10% chordwise length morphing trailing edge flap for a 4 MW wind turbine rotor is carried out and response surfaces are produced with respect to the flap internal geometry design parameters for the design conditions. Surrogate model based optimization is applied in order to converge to a flap design, which maximizes aerodynamic lift control performance while minimizing drag penalty, subject to material strength and manufacturing constraints. The purely structural optimization of the flap response is compared to the coupled aerostructural optimization.