The Effect of Residual Imbalance Type in Vibration Activity of a Double-Span Rotor with Different Curvature of the Axis under Rundown

Abstract

This work is dedicated to comparative estimation of vibration activity of an initial bending double-span rotor with two types of residual imbalance (of that concentrated in the center of each span and of that skew-symmetric relative to the middle of each of the spans), which are differently located relative to the curve of the initial deflection of two types, i.e., with maximum and minimum values of the shape parameter, under transient vibrations at lower critical speeds when rundown. It is revealed that the effect of skew-symmetric imbalance on the amplitudes of transition vibrations of shafting during rundown is particularly essential for natural frequencies, to which the shapes of vibrations with the nodes at each of the spans correspond. The calculations of amplitudes were conducted for the HPR–MLPR system of a turbine of the K-300-23.5, produced by the Leningrad Metallic Plant (LMP). The results obtained were analyzed. Related problems are discussed in [3–8].