Estimation of the Distributing Cross Sectional Asymmetry along the Rotor Axis

A method is presented for estimating the asymmetry of flexural rigidity which varies along a rotor axis. The rotor is pendulously suspended with a couple of ropes and a pair of natural frequencies on two principal planes are measured. Such experimental results are combined with numerical ones for estimating asymmetry. The procedure is discussed in detail and proved to be useful with a simple asymmetric shaft model. The amount of asymmetry on an actual turbogenerator is also estimated and verified to be a sufficiently wide margine for the limit of unstable vibration.