The machines resonate, as do our engineers
State-of-the-art technology is deployed to analyse complex vibration phenomena and ensure the reliability and safety of installations.
Measuring the vibrations of hydroelectric installations is key to ensuring the safety and availability of the facilities operated by HYDRO. The phenomenon known as resonance can rapidly increase the complexity of vibratory phenomena and cause damage. But what is resonance? For the uninitiated, this phenomenon is the same as the tinkling of cowbells on high mountain pastures: the frequency of the structural vibration is determined by the geometry of the structure and its material. In structural dynamics, this is known as an eigenmode or normal mode, associating a frequency with a shape.
Measurement on running or stopped machines
On the equipment that HYDRO operates, the challenge is precisely to determine the presence of a resonance phenomenon. To achieve this, our engineering teams are equipped to perform experimental modal analysis (EMA). This involves measuring the point vibration in the three directions in space using a triaxial accelerometer, by striking the structure at rest in several places with something called an instrumented hammer. The same equipment can also be used on a machine that is running. This is known as determining the operational deformation.
The intervention has already been successfully carried out on Pelton turbines and a double-flow Francis turbine. The modal analysis of a thrust bearing on a vertical Pelton group will soon be performed in a bid to gain a better understanding of the complex vibratory behaviour of its shaft line.
As you can see, nothing will ever stop HYDRO’s engineers from getting to the bottom of things!
Carrying out an experimental modal analysis (EMA) on a double-flow Francis turbine.
Amplitude of vibrations represented in the frequency domain.
Eigenmode of the double-flow Francis turbine.
