[2E6] Detection and signature of the cavitation in centrifugal pumps
S Ganeriwala
SpectraQuest Inc, USA
Timely detection of the occurrence of cavitation in pumps is very important as it can cause pitting, erosion and loss of pump performance. Attempts to determine a unique signature of cavitation using vibration, acoustic emission, audible acoustics and higher-order non-linear modelling techniques have been elusive. This paper presents the results of an experimental study undertaken first to understand the structure of cavitation and then to develop an effective means for online detection of it. Tests were performed to measure vibration, pressure, audible sound, motor current and the force due to cavitation of a centrifugal pump. A special force transducer was developed to measure fluctuating forces exerted by the cavitation process to understand the dynamics of the cavitation phenomenon and signatures of a centrifugal pump. Tests were also run with a transparent LEXAN cover to observe in real time and record the cavitation. Cavitation seems to excite high-frequency structural resonances. Also, fully developed cavitation may reduce the impeller vane pass frequency vibration amplitude. Combined measurement of pressure and vibration seems to provide a more effective means of detection of the cavitation.
