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Title: Aeroelastic tailoring of wind turbine blades for power improvement and load alleviation
Author: Capuzzi, Marco
ISNI:       0000 0004 5924 0850
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2015
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This thesis introduces a novel aeroelastic approach to the design of blades for large-scale wind turbines. Larger blades driven by the demand for cheaper energy may incur aero elastic issues in design. A current blade is used as a reference for an aerodynamic analysis that maximises the turbine's yielded power at different wind speeds via optimisation of the blade's twist distribution. By noting that the total twist is the sum of pre-twist, elastically-induced twist and blade pitch, a distribution of elastic twist is identified. This distribution is induced by the blade bending so that it adaptively aligns the blade's total twist with its optimal distribution at the different operating conditions. The elastic twist distribution: is purposefully forced to be nose:-down along the entire blade's span, so that it also provides a passive capability to alleviate gust loads. Then, the required elastically-induced twist is analysed from a structural perspective and adapted accordingly. Material and geometrical bend-twist couplings are used in the structure to induce the appropriate differential blade twist , section by section, while bending flap-wise. The use of a curved planform and of tow steered laminates is essential, to combine different bend-twist couplings and vary their amount spanwise. A blade design that realises the desired adaptive behaviour is presented and its power performance is compared against classical designs. The proposed design is then analysed with refined finite element models. Structural stability and strength constraints are imposed under realistic load cases, which envelope the operating regime of the blade. Nonlinear effects are analysed as well as modal dynamic features. In this context, a structural optimisation, by means of genetic algorithms, assesses the weight penalty due to the aero elastic tailoring of the spar structure. Finally, the load alleviation due to this adaptive design is assessed and compared to more traditional passive adaptive solutions. Remarkably, the proposed design allows an increase of the blade aerodynamic efficiency and it also adds a passive capability of gust load alleviation. In summary, this research presents an adaptive concept for blades that is able to cope with both power and load requirements simultaneously.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available