Un modello quasi-statico per la determinazione delle condizioni di instabilità di cilindri comunque inclinati rispetto al vento

Quasi-static hypotheses have often been adopted both to model wind forces on moving cylinders in cross-flow and to study instability conditions of rigid cylinders supported by visco-elastic devices. Recently, much attention has been devoted to the experimental study of inclined and/or yawed circular cylinders, detecting peculiar dynamical phenomena such as galloping-like instability. At the present state-of-the-art, no mathematical model is able to recognize or predict satisfactorily this behaviour. This paper presents a generalization of the quasi-static theory for the definition of the wind forces on yawed and inclined circular cylinders. The proposed model is developed using a particular vectorial notation, which seems the most suitable to develop this kind of problems. This model is able both to replicate experimental behaviours, observed during a series of recent wind-tunnel tests performed in Canada, and to predict new instability ranges, which could be the guide of next experimental tests.