Method for judging heavy cavitation of hydraulic machinery runner blade

Abstract

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 pulsation is added, whether the hydraulic machinery runner blade severe cavitation phenomenon occurs or not can be judged according to the corresponding criterion provided by the invention.

Description

technical field [0001] The invention relates to a method for judging the severe cavitation of a runner blade of a hydraulic machine. Background technique [0002] With the gradual improvement of users' requirements for the stability of hydraulic machinery, ensuring the safe and stable operation of hydraulic machinery in the state of no runner blade cavitation, especially the state of no severe cavitation has become an important indicator for evaluating the operating state of the unit. [0003] For hydraulic machinery, from the basic principle, it is not desirable to have any degree of cavitation during the operation of the unit. However, in view of the limitations of the current design and manufacturing technology level and the user's requirements for the continuous expansion of the operating range of hydraulic machinery, hydraulic machinery will inevitably operate in a cavitation state. With the advancement of hydraulic machinery runner blade materials and protection techn...

AI Technical Summary

Problems solved by technology

[0005] At the current level of technology, it is impossible to observe and confirm whether there are cavitation bubbles on the runner blades and whether the cavitation bubbles have detached from the attachment of the blade surface on the prototype machine. Observe the cavitation bubbles on the runner blades through the transparent draft tube under the source, and use this as a basis to infer the cavitation of the prototype under the same cavitation coefficient

Since the state of cavitation bubbles in the model test process is completely carried out by manual visual inspection, there is no uniform and quantifiable standard. As a result, the determination of whether the cavitation bubbles on the runner blades have detached from the attachment on the blade surface depends on the observer and the observation position. There are great differences due to different factors, which will affect the accuracy of the evaluation of the cavitation degree of the runner blades, and will most likely cause unpredictable negative effects on the safe and stable operation of hydraulic machinery.

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