Cavitation Detection in Variable Speed Pump by Analyzing the Acoustic and Vibration Spectrums

Abstract

Cavitation in pumps must be detected and prevented. The present work is an attempt to use the simultaneous measurements of vibration and sound for variable speed pump to detect cavitation. It is an attempt to declare the relationship between the vibration and sound for the same discharge of 780 L/h and NPSHA of 0.754 at variable speeds of 1476 rpm, 1644 rpm, 1932 rpm, 2190 rpm, 2466 rpm, and 2682 rpm. Results showed that: the occurrence of cavitation depends on the rotational speed, and the sound signals in both no cavitation and cavitation conditions appear in random manner. While, surveying the vibration and sound spectrums at the second, third, and fourth blade passing frequencies reveals no indications or phenomenon associated with the cavitation at variable speeds. It is recommended to survey the vibration spectra at the rotational and blade passing frequencies simultaneously as a detection unique method of cavitation.

Development of cavitation detection methodology for hydraulic turbomachines using experimental and numerical tools

“…6.19a) the highest amplitude of the vibration spectra, that coincides with the third harmonic of the total blade passing frequency (TBPF) of impeller No.1 (~1 kHz) seems to decrease when passing to cavitating conditions. This pattern has been reported in similar experiments (Abdulaziz, 2017;Lu, 2017) but contradicts with the results of other researchers (Ganeriwala, 2011;Kotb, 2015), where the low frequency vibration amplitude increased. This odd behavior is due to the fact that the low frequency components of a pump-motor system are strongly dependent from the structural characteristics of each pump under investigation and could not be generalised.…”

Detection of Inception Cavitation in Centrifugal Pump by Fluid‐Borne Noise Diagnostic

“…At present, there are several methods for detecting cavitation inception that are the energy method [5], optical method [6], surface coating method [7], electrical resistance method [8], acoustic emission technology [9,10], and vibroacoustic method [11,12]. With a head drop of 3% or an efficiency drop of 1% as the criterion, the energy method could cause an erroneous estimate because actually the cavitation has developed to a certain extent under these conditions.…”

Assessment of units vibration state and water supply path of Amuzang-2 pumping station

“…The parameter limiting the safe flow pulsation in [20][21][22][23][24][25][26][27][28][29] is the recommended maximum amplitude of pressure pulsation in the pipeline, determined by the formula: ∆Р = (0.20...0.25) Р st (1) where: Р st is static pressure in the desired section of the pipeline. This parameter (pressure fluctuations) is not correct enough for inclined pressure pipelines of the pumping station, where it is not entirely logical to obtain a decrease in the allowable pulsation along the pipeline route.…”