Rotational modes of motion for an aerodynamic pendulum with a vertical rotation axis

An aerodynamic pendulum in a steady horizontal wind flow is studied in connection with modeling a wind-receiving element of a straight winged vertical axis wind turbine (VAWT). The model of aerodynamic action on the pendulum is assumed to consist of two components: the quasi-steady one (using data obtained in stationary wind tunnel experiments) and the non-steady one (taking into account the added masses effect). The question of existence of stable and unstable rotational modes is studied analytically (via the Poincare–Pontriagin method) and numerically. The dependence on parameters responsible for a viscous friction at the shaft and for an influence of added masses is taken into account.