In the early years of the VAWT history, researchers mainly opted for symmetric airfoils since it was believed important that the behaviour was similar in the upwind and downwind part of the rotor and because abundant information was available for symmetric airfoils. This research focusses on the understanding of the desired airfoil characteristics and the design of optimised airfoil shapes for multimegawatt VAWTs with individual blade pitching. To unlock this potential, research is performed on various aspects related to rotor aerodynamics such as the effect of rotor configuration (blade solidity, 6 double-rotor interaction, 7 three-dimensional losses 8, 9), the effect of blade profile (airfoil selection 1, 10, 11 and roughness sensitivity 8, 12, 13), and the effect of using load control (trailing edge flaps, 14- 16 circulation control, 17 and blade pitching 18- 20) on the turbine efficiency. Some researchers stated that VAWTs could achieve maximum power coefficients in line with current HAWTs 1, 2 and even have the potential to decrease the cost of energy in urban applications 3 or for large-scale offshore wind farms 4, 5. To achieve competitiveness compared with the standard HAWT, improving the rotor performance is a key in order to make VAWTs commercial. While horizontal-axis wind turbines (HAWTs) are widely studied and have proven their capabilities, the alternative vertical-axis wind turbine (VAWT) concept is not yet common. The comparison of the optimised airfoils with similar airfoils from the first generation shows a significant improvement in performance, and this proves the necessity to properly select the airfoil shape. The optimal pitch schedule is determined, and the loadings and power performance are studied for different tip-speed ratios and solidities. Three airfoils from the Pareto front are selected and analysed using the actuator cylinder model and a prescribed-wake vortex code. The structural objective focusses on maximising the bending stiffness. At rotor scale, the aerodynamic objective aims to create the required optimal loading while minimising losses.
A genetic algorithm is used to optimise the airfoil shape considering a balance between the aerodynamic and structural performance of airfoils. In this research, airfoils are tailored for a VAWT with variable pitch.
To advance the design of a multimegawatt vertical-axis wind turbine (VAWT), application-specific airfoils need to be developed.
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