Vibration Analysis of Rotating Disk Carrying Annular Concentrated Masses in Turbo-pump System

Abstract

Vibration analysis of rotating disks is one of the most important problems in turbomachines. In this study, a new method has been presented which analyzed the radial vibration of a turbo-pump rotating disk carrying two annular concentrated masses located on the disk and at its end. Natural frequencies have been calculated in different rotating speeds; then results have been compared with each other. The effects of concentrated masses position and intensity on natural frequencies have been investigated. The results show that concentrated masses always have been decreased the value of first natural frequency, but in the case of second and third natural frequencies, depending on the mass concentration magnitude and its position, the magnitude of natural frequency has been increased or decreased. The vibration of the rotating disk without considering the concentrated mass, was examined. Then the resulting solution was generalized for two connected disks in internal concentrated mass location. The effect of concentrated masses, one on the disk body and the other on the outside of the disk, is considered as boundary conditions in the two disk Equations. The results show that increasing in angular velocity of rotating disk reduces the natural frequency. Concentrated masses always reduce the first natural frequency. At the second and third natural frequencies, concentrated masses may increase or decrease the natural frequency, which depends on the value and position of concentrated mass. Concentrated mass has the most impact when it is in a position that has the most radial displacement.

Keywords

• concentrated masses
• free vibrations
• rotating disk
• turbo-pump