Compensating an assembly fault in a gas turbine rotor by in-situ balancing: a case study

摘要

There have been numerous cases in industry where vibration has been assumed to have arisen from mass unbalance and rotors have been balanced using flexible rotor balancing procedures. This paper presents a similar industrial experience on field balancing of a faulty gas turbine rotor. Although the main root of the problem stemmed from an assembly fault, the dynamic behaviour of the rotor was identical to an unbalanced rotor as long as the rotor was cold. In this case study, it is shown that flexible rotor balancing could temporarily decrease the bearing vibrations of the faulty rotor to a permissible value. However, the dynamic behaviour of the rotor significantly changed after warming up and reaching full load, which is attributed to the temperature-dependent nature of the assembly fault in the rotor.