Measurement of Cavitation Erosive Aggressiveness by Means of Structure Born Noise

Abstract

A measuring system was developed to estimate the cavitation erosive aggressiveness in a centrifugal pump during operation. The system is based on acoustical means. Acoustic pressure waves in water and vibrations of machine casings underlie several disturbances especially by changes of the transmission behaviour of the fluid during operation. Thus, an approach based on the structure born noise measured directly on the mechanical structure exposed to the cavitation was chosen to minimise this problems. The sensor, the amplifier and the signal processing and transmission devices have then to be placed within the rotating part of the machine. The measurements of the system have been compared with results of measurements using material specimen and coatings of soft copper. The physical relation between the acoustical event amplitudes detected by the system and the sizes of pits found on the specimen is discussed.