Method for judging heavy cavitation of hydraulic machinery runner blade

The invention discloses a method for judging heavy cavitation of a hydraulic machinery runner blade. A hydraulic mechanical model draft tube pressure pulsation signal is basically not changed along with the change of a cavitation coefficient before the hydraulic mechanical runner blade is subjected to severe cavitation, and the hydraulic mechanical model draft tube pressure pulsation signal is suddenly increased along with the reduction of the cavitation coefficient after the hydraulic mechanical runner blade is subjected to severe cavitation, mathematical statistical analysis is carried out on the draft tube pressure pulsation signal of the hydraulic mechanical model, dispersion change of a hydraulic mechanical model draft tube pressure pulsation signal sequence under different cavitation coefficients is evaluated by a method of calculating a hydraulic mechanical model draft tube pressure pulsation signal dispersion coefficient, and monotonicity change of hydraulic mechanical model draft tube pressure pulsat