Synchronic Vibration and Turbomach “Rubs” or Streaks
Conclusions | Morton Effect in Turbomachinery Blades
Light streaks are commonly encountered in rotating machinery and often give rise to a distinct, cyclical pattern in amplitude and phase trend plots, as well as polar plots. Shaft orbit plots are likewise valuable as they may give direct evidence of more pronounced streaks, observable as flat spots where motion is constrained or “bumps” where the shaft
actually bounces against a stationery surface such as a seal. The Morton Effect yields data similar to a rub because the underlying mechanism (localized heating) is the same.
However, in the case of a rub, the heating occurs due to mechanical friction as rotating and statio- nery parts contact one another, while in the case of the Morton Effect, the heating occurs as the result of excessive shear stresses in the lubricant. Uniting each of these principles, the factors point strongly towards the Morton Effect as the underlying cause of the elevated vibration levels.
This engineering edu-blog has hoped to produce an introductory overview of the Morton Effect, along with showcasing the ways in which polar plots may be used to differentiate this phenomenon from that of a legitimate rub or streaked condition.
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