Turbine blade design

Furthermore, a fine agreement with calculations are found - if the calculations are carried out with the transition point at the leading edge. A design tool for development of airfoils has been established and tested for a 24% airfoil. The tool has been used for the development of the profile series RISØ-A-XX, which has a distinct stall, good aerodynamic performance and low sensitivity to roughness. Several measurements of aerodynamic noise has been correlated to simultaneously measured inflow characteristics. Furthermore, a high-frequency noise problem has been solved for the test turbine. A significant variation in simulated extreme loads has been illustrated, when time domain models are used. A new method of combining the time domain approach with statistical methods reduces the variation by a factor of four. The numerical tool for optimum rotor design has been extended and used in two ways. First, a model for aerodynamic noise has been implemented and the effects of constraints to the noise have been illustrated. Secondly, optimizations for turbines operating in different wind climate have been carried out. The results illustrate the difference in the optimum design for turbines at differents sites. Composite materials for rotor blades are characterised with respect to stiffness, strenght, fatigue and damping. Stiffness constants are measured by several different techniques. Strenght values are compared for different testing configurations. Fatigue data are analyzed in S-N diagrams; the stiffness reductions as a function of number of fatigue cycles is quantified and used to generate stiffness-based fatigue deagrams. Block-loading in fatigue is performed, and based on equivalent stresses fatigue diagrams are calculated. Damping is measured for pure polyester matrix and for composites, and a simple model is established for the composite damping. Hybrid-composites based on glass- and carbon-fibres are tested under some of the fatigue loading conditions