SELF-EXCITED VIBRATIONS OF THE VARIABLE MASS ROTOR FLUID SYSTEM/

In this paper the variable mass rotor/fluid system is considered. A ro tor with variable mass is settled in hydrodynamic bearings. The dynami c properties of the rotor on which the fluid force and the impact forc e (due to mass variation) act are analyzed. The conditions of stable r otation are obtained applying the direct Lyapunov theorem. The self-ex cited vibrations are determined analytically. The Krylov-Bogolubov met hod is extended for solving the second order differential equation wit h a complex deflection function, small non-linearity and time variable parameters and a significant damping term. Analyzing the amplitude of self-excited vibrations, the conditions of unstable motion are define d. Special attention is given to the effect of interactive influence o f the inertial fluid force and the impact force on the stability of ro tation of the rotor. For the rotor on which the band winds up, the vib rations are obtained analytically. The results are compared with numer ical ones. (C) 1998 Academic Press Limited.