The effect of row of blades on self-excited instability of rotating systems

Abstract

The self-excited instability, which is common in rotating systems, is investigated in a bladed disk system. The instability happens due to internal damping and causes asynchronous vibrations. A bladed disk model of the rotor is suggested to study of such instability and related bifurcation around the critical speed. The blades are modeled by inverted pendulum and Duffing’s type nonlinearity is considered for the stiffness of the supports. The equation of motions is derived using Lagrangian formulation and normal form of the equations is obtained by center manifold reduction method. Analytical formulations are derived and validated by numerical simulation. The analysis shows that the blades motions can deteriorate the asynchronous vibrations and even widen the instability region.