Method and device for detecting the natural frequencies of vibration of a turbine blade

摘要

A method for detecting at least one natural frequency of vibration (f V ) of a turbine blade (2) envisages:
- supplying a current (I) of constant intensity and selectively variable frequency (f 0 ) to an electromagnet (4) set in the proximity of the blade (2) for generating a magnetic field adapted to cause a vibration of the blade (2);
- detecting the movement of the blade (2);
- determining at least one natural frequency of vibration (f V ) of the blade (2) on the basis of the movement of the blade (2); and
- detecting a distance (D) between the electromagnet (4) and the turbine blade (2) during the step of supply and block of supply of the electromagnet (4) if said distance (D) is less than a given safety value.