Cavitation Monitoring of Hydroturbines with RMS Acoustic Emission Measurement

Derakhshan, O; Houghton, J. R.; Jones, Richard; March, Patrick A.

doi:10.1520/stp19102s

Cited by 20 publications

(14 citation statements)

References 4 publications

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“…with decreasing NPSH values was attributed to the attenuation caused by bubble clouds. The loss in AE strength due to the presence of cavitation was noted by Neill [15,16] and Derakhshan [14]. This is not surprising if cognizance is taken of the findings of Derakhshan [14] and Hutton [17] where it was noted that when direct contact between the cavitating liquid and the specimen experiencing cavitation (e.g.…”

Section: Npsh Testmentioning

confidence: 93%

Detection of incipient cavitation and determination of the best efficiency point for centrifugal pumps using acoustic emission

Alfayez

2005

Proceedings of the Institution of Mechanical Engineers, Part E:

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Pumps play a significant role in industrial plants and need continuous monitoring to minimize loss of production. To date, published information on the application of acoustic emission (AE) to incipient pump cavitation has been contradictory. This article re-assesses the application of AE for detecting incipient cavitation. In addition, this paper presents results from an on-going programme to ascertain the applicability of the AE technique for determining the best efficiency point (BEP) of an operating system. Three different sized pumps (60 kW, 127 kW, and 2.2 MW) formed the basis of this investigation, which included NPSH (net positive suction head) and performance tests. Results obtained demonstrate the successful use of the AE technique for detecting incipient cavitation and highlight the enormous potential of the technique in determining the BEP of a pump or system.

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Section: Npsh Testmentioning

confidence: 93%

Detection of incipient cavitation and determination of the best efficiency point for centrifugal pumps using acoustic emission

Alfayez

2005

Proceedings of the Institution of Mechanical Engineers, Part E:

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“…Beeswax was chosen following tests with various methods for the attachments prior to the investigation. Additionally, several other researchers have in previous tests used beeswax as a couplant for acoustic measurements [3,11].…”

Section: Methodsmentioning

confidence: 99%

Absolute Measurement of Elastic Waves Excited by Hertzian Contacts in Boundary Restricted Systems

et al. 2016

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In most applied monitoring investigations using acoustic emission, measurements are carried out relatively, even though that limits the use of the extracted information. The authors believe acoustic emission monitoring can be improved by instead using absolute measurements. However, knowledge about absolute measurement in boundary restricted systems is limited. This article evaluates a method for absolute calibration of acoustic emission transducers and evaluates its performance in a boundary restricted system. Absolute measured signals of Hertzian contact excited elastic waves in boundary restricted systems were studied with respect to contact time and excitation energy. Good agreement is shown between measured and calculated signals. For contact times short enough to avoid interaction between elastic waves and initiating forces, the signals contain both resonances and zero frequencies, whereas for longer contact times the signals exclusively contained resonances. For both cases, aGreen's function model and measured signals showed good agreement.

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“…In addition, in a fluid system the AE could be attenuated/excited by sources such as bubble activities including bubble formation, coalescence, break-up and collapse/burst [5][6][7]. The other sources of AE generation in liquid flow are flow turbulence, flow past restrictions, liquid flashing and recirculation/turbulence [5,[8][9][10]. Those sources caused a change of pressure wave or sound pressure in liquid.…”

Section: Background Work Of Bubble Detectionmentioning

confidence: 99%

Study of the application of Acoustic Emission technology for on-line monitoring of bubble phenomena and flow patterns in two-phase gas-liquid flow

Husin¹,

Addali²

2012

Advances in Fluid Mechanics IX

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An investigation into single bubble dynamics detection in a liquid-filled column, and monitoring and measurement of gas void fraction in a horizontal pipe using AE technology has been performed. A correlation between Acoustic Emission (AE) and Gas Void Fractions in two-phase gas-liquid flow in a horizontal pipe has been established from this work. The results demonstrate the feasibility of employing AE technology as an on-line monitoring tool for bubble dynamics and flow patterns in two-phase gas-liquid flow in pipes.

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Cavitation Monitoring of Hydroturbines with RMS Acoustic Emission Measurement

Cited by 20 publications

References 4 publications

Detection of incipient cavitation and determination of the best efficiency point for centrifugal pumps using acoustic emission

Detection of incipient cavitation and determination of the best efficiency point for centrifugal pumps using acoustic emission

Absolute Measurement of Elastic Waves Excited by Hertzian Contacts in Boundary Restricted Systems

Study of the application of Acoustic Emission technology for on-line monitoring of bubble phenomena and flow patterns in two-phase gas-liquid flow

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