ICING ON WIND TURBINES

The motivation of this thesis is a Comprehensive analysis of the phenomenon of icing on wind turbines. The interest on the icing problem of wind turbines and on methods for its mitigation as well as to predict its e ect on load, control system, power production etc., has grown signi cantly in the very latest years due to the increasing number of installation of WT in icing risk areas. Research and development of ice accretions and anti-icing analysis is a multidisciplinary activity encompassing various research elds and competences as meteorology, aerodynamics, heat transfer and ice physics, together with the knowledge of wind turbine operation, economics, manufacturing details, and not last, regulations. Icing process is one of the more challenging application eld of computational thermo- uid-dynamic.This thesis covers most of the concerns of wind turbines operating in cold climates, with large part devoted to the analysis of icing and methods for its mitigation. Several articles and reports appeared in the last 60 years on icing of aircraft, more experience has been gained in this eld together with methods and technical solution. The transfer of this knowledge to wind energy eld is nevertheless not obvious, since many di erences arise between aeronautical and wind applications. These are due to climatic conditions at which they are calibrated, the operating angles of attach of the pro les, and the e ect of rotation. The use of existing codes for wind turbines in icing conditions analysis is therefore not straightforward. To accomplish the general task of the thesis, the mat has been divided in ve chapters, each of them developing progressively the basic knowledge for a comprehension of the subject. The analysis has lead to two main results: the rst was an organic and rational systematisation of the topic, the second was the creation of several original analytical and numerical models helpful for ready computation. Due to the number of arguments treated, the calculations and examples developed, both on uid-dynamic, and thermodynamic, the work took at the end the form of a manual where the scienti c analysis has resulted in technical tools for general design tasks.