The transmission of acoustic emission across large-scale turbine rotors

Seal and blade-tip rubbing in turbo machinery can often result in costly rotor damage. Acoustic emission analysis at the bearings has previously been cited as a viable non-destructive monitoring technique by which the onset of such rotor-stator contacts can be detected in large-scale turbines [Aerospace Conf., IEEE Proc. 6 (2000) 79; Electr. Engng Jpn 110 (2000)]. These studies suggested that the stress waves or acoustic emissions produced during the frictional rub process can propagate across the turbine surface and across the bearing interfaces to be detectable by the sensor attached to the bearing housing. However, results from the actual large-scale turbine units have been scarce. This paper presents a fundamental/pre-requisite study on the transmissibility of acoustic emission (AE) signatures across very large-scale turbine rotors. It is concluded that the actual AE attenuation incurred does not inherently exclude the detection of seal and blade rubbing in turbines. However, its success is highly dependent on advanced signal processing. (C) 2002 Elsevier Science Ltd. All rights reserved.