Method for ultrasonically detecting T-shaped blade roots of in-service steam turbine blades

Abstract

The invention discloses a method for ultrasonically detecting T-shaped blade roots of in-service steam turbine blades. The method includes steps of S1, determining sizes; S2, selecting ultrasonic probes; S3, selecting incidence points; S4, simulating paths; S5, carrying out actual operation; S6, determining crack locations. The step S1 includes determining the structure sizes according to drawingsfor the T-shaped blade roots. The step S2 includes that the conventional ultrasonic probes are selected, selected refraction angles need to be 35-45 degrees, and included angles between the advancingdirections of transverse waves and chamfer circular arcs need to be changed into tangent states when the transverse waves are subjected to incidence to chamfers of variable cross sections of the blade roots. The step S3 includes adjusting the probes on CSK-IA test blocks and finding the incidence points of acoustic waves on the probes. According to the scheme, the method has the advantages that the crack locations of the steam turbine blades can be quickly positioned by the aid of the method, and the method is in simple operation modes; the method for detecting the steam turbine blades is high in accuracy; the method for detecting the steam turbine blades is little in environmental limitation.

Description

technical field [0001] The invention relates to the field of detection of steam turbine blades, in particular to an ultrasonic detection method for T-shaped blade roots of steam turbine blades in service. Background technique [0002] Steam turbine blades in thermal power plants have been operating in a high-temperature and high-pressure environment for a long time, and the stress and working conditions are complex. They are mainly affected by the thrust of the steam flow from the steam inlet to the steam outlet direction, the centrifugal force of the rotor at high speed, the alternating stress when the turbine starts and stops, and Thermal stress, as well as the vibration caused by airflow fluctuations and the binding effect of the blade root groove on the blade root. The T-shaped blade root of the steam turbine is fixed by the T-shaped blade root groove on the rim of the steam turbine rotor impeller. After a long time of operation, cracks are likely to occur at the variabl...

AI Technical Summary

Problems solved by technology

However, due to the various sizes of the T-shaped blade structure, each method has its own limitations:

[0004] During longitudinal wave detection, the non-blade body contact area of ​​the T-shaped blade root end surface on the blade body side is too small or the detection space is limited, so the longitudinal wave probe cannot be placed or the longitudinal wave probe cannot be moved;

[0005] When the shear wave is detected, the curvature of the blade body is too large, and the shear wave probe cannot contact the blade body or the contact is unstable;

[0006] When the surface wave is detected, the connection position between the blade body and the blade root is not smooth enough, or when there is a structural mutation, the surface wave sound beam cannot reach the inspected part;

[0007] During deformation wave detection, limited by the size of the exposed shoulder, it is generally necessary to customize a special small chip and a short-front probe so that the incident point of the sound wave is on the exposed shoulder. If the size of the exposed shoulder is too small, the customized probe cannot make the incident The point is on the exposed shoulder or the refraction angle of the sound beam cannot meet the requirement that the sound wave reach the chamfering position of the variable cross section to generate deformation waves, but it still cannot be detected

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