Paper 6: Notes on the Measurement of Vibrations on Rotating Systems

In analysing the vibrations of rotating systems it is often advantageous to trace the path of the shaft centre from vibrograms taken by two instruments at 90 degrees, because the resulting patterns can yield valuable information about the mechanism of excitation. It is also shown that the same pattern can represent several types of vibration, but for a correct identification it is necessary to know in what sense the patterns have been described. Instrument deflections for some simple cases of transverse vibrations, whirlings, and two-component whirlings are analysed both in stationary and in synchronously rotating co-ordinates and a few typical patterns are shown. Some inherent characteristics of stationary instrumentation are discussed.