Critical conditions of galloping for inclined square cylinders

Abstract

This paper concerns the study of galloping critical conditions on square cylinders with an arbitrary attitude in the wind flow. It is based on a consistent theoretical model of wind actions, which permits the analysis of a generic-shaped cross-section. A generalized definition of the aerodynamic damping matrix as function of both the angle of incidence and the angle of skew is proposed. The availability of specific experimental data allows a sound definition of aerodynamic actions. The analysis of critical conditions can be performed in closed form in the plane of the aerodynamic damping matrix invariants. Preliminary results obtained in smooth-flow conditions point out that yaw effects might influence critical conditions from a quantitative point of view, but do not destroy the instability domain obtained in the classical cross-flow conditions.