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On-line rotor crack detection

  • US 4,380,172 A
  • Filed: 02/19/1981
  • Issued: 04/19/1983
  • Est. Priority Date: 02/19/1981
  • Status: Expired due to Term
First Claim
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1. For a motive fluid powered turbine, a method for detecting incipient cracks in the turbine rotor while the turbine is under load at substantially normal operating speed, comprising the steps of:

  • (a) obtaining from at least one vibration sensor, adapted to sense vibrations in said rotor, a signal representation of such vibrations;

    (b) determining the spectral distribution of said vibration signal;

    (c) causing a transient perturbation of said rotor to establish a transient vibratory response therein by changing the temperature of the turbine motive fluid;

    (d) determining the spectral distribution of said vibration signal resulting during said transient vibratory response, and(e) comparing the spectral distribution obtained in step (b) with the spectral distribution obtained in step (d), the change in spectral distribution between that of step (b) and that of step (d) being indicative of the presence and size of cracks in said rotor.

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