Section C Structures - Characteristics of the Windmill Structural Fatigue Load in Natural Wind

In recent years, wind power generation has been gaining attention in many countries around the world as a source of renewable energy. However, windmill-related accidents are occurring frequently in its introductory stages in Japan and, compared to other countries, are leading to a slower increase in installation. Causes of the aforementioned accidents are irregular winds arising from the terrain and specific weather conditions. In this study, experiments using many patterns were conducted in which inflow wind velocity, pitch angle, and rotation speed were changed. The purpose was to observe the bottom load of a wind turbine tower. A model similar to that of an actual wind turbine was produced, and the load, which influenced the bottom, was investigated by using a six-component force transducer. The results showed that each relationship between the pitch angle, load, and wind speed became clear. The relationship between the drag and the lift also became clear by analyzing load data. From the dimensionless data, which was used for the initial load, the increasing tendency of the load, due to the difference of pitch angle, was revealed. In addition, the change of the load following a sudden change of wind velocity became clear. Furthermore, the usefulness of the feathering was also confirmed.