Field experiences with rub induced instabilities in turbomachinery

Rotordynamic instability problems are not uncommon in high speed industrial turbomachinery. One type of the many destabilizing forces that can occur is caused by a rub between the stationary and rotating parts. Descriptions are given of several cases of rub induced instabilities. Included in the descriptions are the conditions at onset, the whirl frequency and direction, and the steps taken to eliminate the problem.