VAWTDYN: a numerical package for the dynamic analysis of vertical axis wind turbines

In order to design wind turbines which possess long life and at the same time use a minimum quantity of low-cost materials, it is essential that dynamic, in addition to static, structural analyses be performed to eliminate unnecessary margins of safety resulting from undetermined dynamic amplifications. The VAWTDYN package provides a tool for assessing these amplifications in two-bladed vertical axis wind turbines. The dynamic model on which the package is based contains turbine motions most commonly observed in existing research systems. Gyroscopic effects, structural damping, aerodynamic wind loading, and power generation through either an induction or synchronous generator are also included in the model. In addition to a comprehensive description of the model, this report documents the efforts that have gone into the verification, qualification, and demonstration of the package.