Self-excited Oscillation of a Hollow Rotating Shaft Partially Filled with a Liquid : 1st Report, Instability Based on the Fluid Force Obtained from Boundary Layer theory

A self-excited oscillation of a hollow rotating shaft partially filled with a liquid is investigated both theoretically and experimentally. In this report, the theoretical explanation about the mechanism of a self-excited oscillation is give, the validity of which is confirmed by experiments using a model with one degree of freedom. The results show that the fluid force acting on the wall of a hollow rotating shaft consists of two components, one of which is out of phase by 90 degrees with the displacement of the shaft and that this component makes the field of rotating resistance with resonant characteristics which causes the self-excited oscillation.