Parametric oscillations of wings excited during nonuniform fluid flow

Abstract

The mechanism of excitation of rotary parametric oscillations during nonuniform fluid flow in a partially filled wing with a pivotal bearing and elastic connections is examined. It is experimentally revealed that at a certain flow velocity, intensive wing oscillations are excited with an eigenfrequency approximately twice as high as rotary oscillations alone. When the air cushion is removed and the wing is filled completely by the liquid, these oscillations stop. It is shown that significant modulation of the mass moment of inertia with a period equal to the half-period of self-oscillations appear due to significant displacements of the air cushion and liquid displacement towards the peripheral segments of an incompletely filled wing during rotary oscillations. Therefore, the parametric intensification of rotary oscillations of a wing in nonuniform liquid flow at a frequency approximately twice as high as the eigenfrequency can take place. The intensive rotary oscillations of an incompletely filled wing, which are excited by a nonuniform liquid flow, can be efficiently used for driving the different mechanisms in machine manufacturing, power engineering and the shipbuilding industry