The development of a representative 2.5 MW class wind turbine class wind turbine fluid-structure interaction model

The simulation of the complex flow in the wake of a Horizontal Axis Wind Turbine and how it infuences the structural response of the blades is a challenging problem. The difficulty of this problem is further increased when the scale of modern turbine facilities is considered. The substantial size of turbine blades has meant that design tools have had to evolve from simple static calculations that assume a constant wind loading to detailed dynamic calculations that take into account the unsteady aerodynamic loads and aeroelastic response of turbine blades. The Shear Stress Transport (SST) k-w, Reynolds Stress Transport (RST) and Elliptical Blending-Reynolds Stress Model (EB-RSM) turbulence models were used to model a turbine wake in the current study, with the results verified against experimental hot-wire data. The numerical data was compared to experimental results for two Tip Speed Ratio (TSR) values of 2.54 and 3.87. The experimental investigation focused on the near field wake with data taken from 0.66D (D is defined as the rotor diameter) to 1.5D downstream. Initial comparisons show that the use of high delity models is not required to predict the turbulent characteristics of the flow and that all models predicted rms velocities and u'v' Reynolds Stresses to the correct order of magnitude. All models proved capable to predict Reynolds stress values in the wake with percentage errors ranging between -34% and 17% over the two TSR values. In addition to increasing the difficulty of aerodynamic modelling of wind turbines, larger blades increase blade flexibility and increase the complexity of structural models also. Currently, due to the size of blades, no data is available to the research community regarding their structural properties and performance during operation. Data such as this will be required to validate larger structural models in the future. A novel methodology was adopted to benchmark a Fluid-Structure Interaction (FSI) model of a representative 2.5 MW commercial wind turbine. The method involved comparing blade deflection data from a field turbine, similar in size to the numerical model. It was proposed that blade defection data (recorded in the field) of a similar sized turbine to the numerical model could be used to evaluate the performance of the numerical model. This would also give opportunity to the research community to deviate from the current process of validating structural models against previous numerical works. Blade defection data was recorded from an operating Nordex N90 wind turbine and used to benchmark a numerically modelled 2.5 MW class turbine. The method involved coupling both a structural model developed in the Finite Element (FE) solver ABAQUS and an aerodynamic model developed in the Finite Volume (FV) solver Star CCM+. The FSI model was carried out with one-way coupling between both solvers. The FSI model was shown to behave correctly with blade deflection values in front of the tower structure falling within one standard deviation of the mean recorded field deflection values. The influence of the blade/tower interaction was also investigated. The tower shadow was shown to effect a significant portion of each blade's rotation cycle (roughly 40 left and right of the tower centre) and caused a reduction in blade moment up of to 29%. The passing of the blade in front of the tower structure effectively pushed the tower stagnation point off centre and resulted in a periodic reduction in the pressure loads applied to the tower.