Fatigue failure analysis of bulb turbine sealing gland bolts based on vibration signal

Abstract Aiming at the issue of fatigue fracture of the sealing gland bolts, this paper takes a bulb tubular turbine with frequent breakage of sealing gland bolts as the research object, establishes a finite element model of the sealing gland, and collects the vibration signals of the sealing gland under three common working conditions through vibration tests. Based on the vibration signal data and dynamic analysis, the vibration fatigue load spectrum of the sealing gland is calculated, and then the fatigue analysis of the sealing gland bolts is carried out. The results revealed that vibration of the sealing gland in the -X direction is much more severe than that in the +X direction, and the minimum fatigue life of the sealing gland bolt group in the - X direction is much shorter than that in the +X direction. Comparing the fatigue analysis results of the ±X-direction sealing gland bolts under different working conditions, it is found that under the same test water head, the service life of the sealing gland bolts under stable operation of 15MW is longer than that of 10MW and 20MW. It is recommended to take measures to reduce the problem of excessive vibration in the -X direction of the unit.