Ultrasonic phased array detection method for fir type blade roots of nuclear main turbine

Abstract

The invention belongs to the technical field of nondestructive detection of a steam turbine for a nuclear power station, particularly relates to an ultrasonic phased array detection method for fir type blade roots of a nuclear main turbine and aims to adopt an ultrasonic phased array detection technology to overcome the defects of small space between blades, complicated blade root structure, signal identification difficulty and the like of conventional ultrasonic detection in a state that blades of a low-pressure rotor of the nuclear main turbine are not dismounted. Four scanning modes are adopted for cross scanning to realize full-area coverage of first tooth roots of the blades and partial coverage of second and third tooth roots, and the defects are accurately quantified, so that the accident of breakage of the blade roots of the blades of the nuclear main turbine is prevented. The method is characterized by comprising steps of system calibration, detection starting and display judgment and quantification. The method has the advantages as follows: ultrasonic detection is carried out without dismounting and mounting of the blades, and the maintenance time is shortened; the four scanning modes are adopted for cross scanning and mutually complemented, and full-area coverage detection of the first tooth root parts of the fir type blade roots is realized; fan-shaped scanning and deep focusing can be realized.

Description

technical field [0001] The invention belongs to the technical field of non-destructive detection of steam turbine equipment in nuclear power plants, and in particular relates to an ultrasonic phased array detection method for the roots of fir tree blades of nuclear power steam turbines. Background technique [0002] A nuclear power steam turbine (Nuclear Main Turbine, NMT) is a large-scale important rotating equipment in a nuclear power plant. The root of a part of the nuclear power steam turbine low-pressure rotor blade is designed as an arc fir tree, such as figure 1 shown. The working stress of the fir tree blade root usually reaches the maximum value at the first dedendum. During the long-term use of steam turbines, changes in load, temperature, stress, and soda quality mainly affect the safe operation of the blades from the high-cycle fatigue damage and stress corrosion of the blade roots, and the material integrity of the first dedendum has the greatest risk. During ...

AI Technical Summary

Problems solved by technology

[0007] The purpose of the present invention is to overcome the deficiencies of conventional ultrasonic detection due to narrow spacing between blades, complex blade root structure, and difficult signal recognition by using ultrasonic phased array detection technology without dismantling the blades of the low-pressure rotor of a nuclear power steam turbine. Four scanning methods cross-scan to realize the full volume coverage of the first dedendum of the blade and the partial coverage of the second and third dedendum, and accurately quantify the defects to prevent the occurrence of steam turbine blade root fracture accidents

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