DETECTION OF CAVITATION PHENOMENON IN A CENTRIFUGAL PUMP USING AUDIBLE SOUND

Abstract

One of the sources of instability in a centrifugal pump is cavitation phenomenon. Cavitation within a centrifugal pump can cause more undesirable effects, such as deterioration of the hydraulic performance (drop in head-capacity and efficiency curves), damage of the pump by pitting and erosion and structure vibration and resulting noise. Cavitation can appear within the entire range of operating conditions; therefore it must, by all means, be prevented. To prevent the onset of the cavitation, we have to know the beginning of cavitation phenomenon in the pump. To detect the beginning of the cavitation process, the emitted noise can also be used, among other possibilities. Experiments have shown that there is a discrete frequency tone within the audible noise spectra, at 147 Hz or BPF/2, which is strongly dependent on the cavitation process and its development. Therefore, the discrete frequency tone at 147 Hz was separated from the noise spectra of cavitating pumps and then used to detect the incipient of cavitation and its development. It was also used to determine the net positive suction head required or the critical value, as well as to prevent cavitation in the pump by means of initiating an alarm, shutdown or control signal via an electrical control system.