Rubbing determination device for rotary machine, and rubbing determination method

A rubbing determination device for a rotary machine for determining rubbing in a rotary machine having a rotary part that is supported by a bearing to be rotatable with respect to a stationary part, the device comprising:

• an AE signal acquisition unit that acquires an AE signal from an AE sensor attached to the stationary part;
• a signal analysis unit that specifies a local maximum value and a local minimum value for an envelope obtained by performing envelope processing on a temporal change in the AE signal and that calculates a first frequency average spectrum corresponding to a first time period including the local maximum value in the temporal change and a second frequency average spectrum corresponding to a second time period including the local minimum value in the temporal change;
• a first signal intensity ratio calculation unit that calculates a first signal intensity ratio as a ratio of a signal intensity in a frequency band higher than a reference frequency in the first frequency average spectrum to a ratio of a signal intensity in an entire frequency band of the first frequency average spectrum;
• a second signal intensity ratio calculation unit that calculates a second signal intensity ratio as a ratio of a signal intensity in a frequency band higher than the reference frequency in the second frequency average spectrum to a ratio of a signal intensity in an entire frequency band of the second frequency average spectrum;
• a first index calculation unit that calculates a first index as a ratio of the first signal intensity ratio to the second signal intensity ratio;
• and
• a rubbing determination unit that determines whether the rubbing is present or absent based on the first index.