| dc.description.abstract | Explanations and guidelines for the phenomena of cavitation noise above the NPSHR of a pump are presented, backed by laboratory and field tests. The hydraulic Institute Concepts of low, and very high suction energy, and NPSH margin are explained and related to cavitation noise and suction pressure pulsations. Cavitation is shown to exist above the NPSHR of a centrifugal pump, and be related to the suction energy level. High suction energy pumps above a certain threshold, with low NPSH margins, can produce severe cavitation noise, especially at reduced flowrates. Test results on an end suction pump also demonstrate the interaction between the air content in the water and cavitation noise within the pump, over varying NPSH margin ratios, flowrate, and speed (energy level). A small amount of air is shown to dramatically reduce the suction pressure pulsation levels. Further, suction pressure pulsation levels are seen to increase as the NPSH margin is reduced, until dissolved air begins to come out of solution and reverse the trend. Finally, test results show the negative effects of piping elbows close to the pump inlet on cavitation noise, especially with high suction energy levels. | en |
