Generator blade vibration

Why do turbine blades vibrate?

The mechanical sources of blade vibrations are due to the vibration of the turbine rotor and the vibration of the discs carrying the rotor blades. The frequencies of the periodic forces in this case are the first and higher harmonics of the rotor speed. In some cases, the so-called self-excited vibrations may also occur.

How rotor blades damage a gas generator?

The rotor blades are directly connected to the hub of the rotor system, and the erosion damage to the rotor blades is closely related to the vibration state of the rotor system of the gas generator , , , .

How is blade vibration measured?

Blade vibration was measured using semiconductor strain gauges attached to the L-0 blades of the low-pressure turbine and a telemetry system for transmitting gauge signals to the stationary side without any mechanical contact.

What causes torsional vibration in a turbine generator shaft?

In turbine generator shafting, in addition to the bending (or lateral) vibrations of the rotor shaft caused by mass unbalance excitation, attention must be paid to torsional vibration of the shaft. The unbalanced torque induced in a generator generally excites torsional vibration of the shafting.

Why do rotor blades vibrate?

Stress risers and corrosion vibrations. Periodic forces, which excite the vibrations of the significantly reduce the fatigue strength of the blades, rotor blades, can have an aerodynamic and mechanical resulting in initial cracks that propagate due to dynamic character. Purely aerodynamic causes of vibration are due to stresses.

Do resonant vibrations affect turbine blade life?

But, when the excitation frequency matches with the blade’s natural frequency, resonant vibrations induce High Cycle Fatigue (HCF), which has a direct effect on turbine blade life. Poursaeidi and Salavatian , stated that HCF failure is mainly related to the bending stresses on blades caused by resonance in the first vibration mode.