Damped rotational vibrations of a long cylinder with a disk in the air flow

Abstract

Abstract We consider the drag and the damped rotational oscillations of a cylinder. The cylinder length-to-diameter ratio is nine. At the upstream end of the cylinder, a disk is mounted coaxially on the leg. The disk reduces the drag of the cylinder. The effect of the disk on damping of oscillations is described by aerodynamic rotational derivatives. Experiment in the wind tunnel is carried out with the flow past a cylinder fixed on an elastic spring suspension. In experiment, the diameter of the coaxial disk, position of axis of rotation and the gap between the disk and the cylinder vary. Deflected from the equilibrium position, the cylinder performs damped oscillations. The dependence of the amplitude of angular oscillations on time is determined by the tensometric method. Aerodynamic coefficients of rotational derivatives are found.