Centrifugal & Rotary Pumps

Detection of Cavitation Phenomenon in a Centrifugal Pump Using Audible Sound

“…6 we can also see that the incipience of cavitation is much sooner then is reflected in the curve of total noise level ðL p Þ or in H: According to [7], cavitation noise appears sooner than the drop of total delivery head due to the additional 'thermodynamic' effect causing an additional adiabatic evaporation of liquid and unsteady cavitation oscillations and noise. Figure 6 is also in an agreement with the findings of other authors [18][19][20] and statements of those who cited them [6][7][8][9], but it is not in agreement with them in the real time and frequency domain. In McNulty's report [18,19], the noise due to cavitation starts to rise much sooner before the H starts to fall and falls before the NPSH required was achieved.…”

“…Nevertheless, relatively few original studies have been published in which sound waves are regarded as a source of information for monitoring the onset of cavitation and its development in centrifugal pumps [18][19][20]. Citation of these works can be found in many books [5][6][7][8][9]. Common to all these studies are measurements of noise emission in ultrasound, up to 1 MHz: As a transducer, a hydrophone or an AE sensor appropriate for high-frequency range were used.…”

“…The method is similar to the previous one, but simpler and, unfortunately, less accurate. The measured signal may be contaminated and corrupted by background noise, such as that of aerodynamical, mechanical and electromagnetic origins, which attenuate or amplify the measured signal [6,7,17]. According to the literature used, the cavitation noise is broadband in nature and pronounced mainly in the high-frequency range}in ultrasound.…”

“…Many researchers prefer to use a hydrophone mounted as close as possible to the place of appearance of cavitation and presentation of results in the frequency domain [6,7,9].…”

An Analysis of the Surface Geometric Structure and Geometric Accuracy of Cylindrical Gear Teeth Manufactured with the Direct Metal Laser Sintering (DMLS) Method

“…The EOS StainlessSteel GP1 material used for fabricating the gears consists of high-chromium stainless steel, the chemical composition of which complies with standard PN-EN-10027-2 steel 1.4542 [18]. GP1 steel is characterized by good mechanical properties, in particular, excellent ductility.…”