[2E1] Cavitation detection based on instantaneous angular speed
T Verwimp¹, G Mousmoulis¹, K Gryllias¹ and A Hajnayeb²
¹KU Leuven, Belgium
²Shahid Chamran University of Ahvaz, Iran
The study and detection of cavitation in hydraulic turbomachinery has recently gained particular attention from both manufacturers and end-users, due to the damage caused on machines’ surfaces that may result in costly sudden shutdowns. The main cavitation detection approaches exploit noise and vibration measurements that sense the vapour bubble implosion pressure waves, while advanced demodulation techniques are used in order to locate the resonances excited from these waves. This work aims to investigate an alternative methodology, where detection is achieved by processing the speed signal of rotary encoders. The motivation is that, contrary to microphones and accelerometers, the encoder is mounted directly on the shaft where the rotor is connected and, thus, is in direct contact with the cavitation waves. More specifically, in this study a centrifugal pump is tested under healthy and cavitating conditions, while an incremental encoder is rigidly installed on the pump’s shaft. The encoder’s signal is processed in order to estimate a raw speed signal. The order spectrum is finally used in order to extract diagnostic indicators based on a discrete or a range of orders amplitudes. From the results, it can be concluded that particular components can provide useful insights allowing for the detection of both heavy and medium intensity cavities.
