Development of a cost efficient wind turbine blade for low wind speeds
Van der Walt, J.L.
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With the growth of renewable energy in recent decades, innovative methods of power production are being researched to reduce humanity’s dependency on finite- and pollution prone fossil fuels. In order to expedite the shift toward renewables as the primary source of global energy, the manufacturing and production cost of components in renewable power production must be reduced. When considering the cost of producing wind turbine rotors and utilising these wind turbines in areas with low wind speeds (conventionally deemed unfeasible areas for wind farms), it is challenging to justify the use of wind energy. By lowering the manufacturing cost of the rotor blades and redesigning the blade characteristics for low wind speeds (such as those found in South Africa’s inland regions), the production cost of energy may be lowered, thus increasing its feasibility as a power generation method. This study investigated the use of rotational moulded polyethylene and a redesign of the rotor for low wind speeds such as those found in Potchefstroom, in South Africa’s North-West province. By integrating the aerodynamic and structural design processes and determining the ideal design wind speed to serve as the base for the design, the blade was increased in length until a maximum size was reached that would satisfy the conditions for safety factors without any internal reinforcement. The study used a blade element momentum theory-based aerodynamic design, and fed the blade-, environmental-, and airfoil characteristics into a beam-theory based structural model. Subsequently, the blade was increased in size until it could no longer withstand the region’s simulated gust-wind conditions. The aerodynamic model was verified and validated by comparing the blade’s predicted performance with results of a similar wind turbine blade’s experimental testing. Using the parameters and loads obtained from the acronymic model the beam-theory based structural design was verified by using a finite element method software package. The software’s capabilities were then compared with real-world testing done on similar structures. The integrated design model may be used for any environmental conditions or regions, and will provide an accurate prediction of an optimised rotor blade design and its performance.