Author(s): P. Sevcik; R. Bischof; L. Rinka

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Abstract: The OSC Hydro Power Group has carried out many performance tests on various types of hydraulic machines. Scan of ultrasonic cavitation emission has been often part of these tests. In addition to the principle used (in our case, modulation of the ultrasonic emission of flowing water by imploded bubbles), also the ultrasonic sensor placement on the turbine body has an influence on the cavitation sensing success and reliability of measurement results. This paper presents our experience with cavitation measurements at various locations in the turbine body. Our effort was always to install the contact microphone as close as possible to the point where the cavitation had a typical manifestation (surface greying, material loss). These positions are often located in concreted parts (e.g. runner chamber) usually inaccessible for sensors. Due to the fact, it is necessary to place the sensors at the locations where at least part of the cavitation implosion occurs. We present recommendations, supported by many real tests, where optimal results can be expected. The results of the determination of cavitation zones are supported by examples from measurements mainly on Kaplan but also Francis turbines, which helped to protect them from cavitation damage by excluding operation in hazardous areas.

DOI: https://doi.org/10.1088/1755-1315/1561/1/012015

Year: 2025