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Vibrations of Blades and Blade Disks
MEASUREMENT OF VIBRATION OF STEAM AND GAS TURBINES,
COMPRESSORS AND BLOWERS’ BLADES AND BLADE DISKS
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| Measuring stand for the examination of resonant vibration of turbines’ blades |
Rotor with new blades |
Such measurement is conducted in order to:
- Determine the frequency of static tangential free vibration of blades,
- Define, in the course of the repair of a given blade system, a safe degree of dynamic free vibration frequencies’ offset from exciting forces that could cause dangerous resonant vibration,
- Define a degree of offset from resonance for blades and blade packs,
- Define, in the course of the repair, a safe degree of offset of blade discs’ dynamic free axial vibration frequencies from exciting forces that could cause dangerous and destructive resonant vibration,
- Define the type of vibration and the value of dynamic frequencies,
- Make sure that blade disks are mounted correctly on the turbine’s shaft of the rotor while the rotor is disabled,
- Determine the possibility of disc looseness according to the frequency of exciting forces occurring in the course of operation in order to eliminate instability (self-excited vibration) of the rotor caused by dry friction,
- Analyse the possibility of avoiding the standing wave as the most destructive form of disc vibration of the blade system,
- Analyse the causes of the blade system’s failure.
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| The utmost degree of blade erosion of the rotor |
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| Example of blades mounted on a blade disc |
We indicate loosenings or any possibility of looseness in the blade disk or clutch plate mounting on the shaft of the rotor. Measurement is carried out when the rotor is disabled, for example, during a repair of the unit. For this purpose, we use a method developed by the VIBROPOMIAR Company on the basis of modal analysis.
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