Water experiment on phased array acoustic leak detection system for sodium-heated steam generator

Chikazawa, Yoshitaka; Yoshiuji, Takahiro

doi:10.1016/j.nucengdes.2015.04.008

Cited by 9 publications

(10 citation statements)

References 4 publications

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“…Given the practical importance of the above problem in the complex framework of leak noise detection and propagation [23], it is worthwhile to explain it in some more detail. In recent years, a beamforming approach based on vibration measurements on the external hull of the SGU rather than on acoustic measurements [24][25][26][27] was studied in a collaboration between the French Alternative Energies and Atomic Energy Commission (CEA), and the Institut National des Sciences Appliquées (INSA) Lyon. The basis of the approach was developed in the framework of the PhD thesis of Moriot (2013).…”

Section: Introductionmentioning

confidence: 99%

Spatial coherence of pipe vibrations induced by an internal turbulent flow

Maxit

Karimi

Guasch

2021

Journal of Sound and Vibration

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Whereas the spatial coherence of wall pressure and vibratory fields induced by turbulent boundary layers (TBLs) on flat plates have been studied at extent, their equivalents for cylindrical structures still need further investigation. To that end, this work develops a semianalytical model which is valid for infinite cylindrical shells filled with a heavy fluid and excited by an internal TBL. The cylindrical shell can be also coupled to two ring stiffeners that account for the flanges generally used to connect a pipe to other portions of a circuit. The crossspectrum density (CSD) function of the shell radial accelerations is estimated from the system circumferential sensitivity functions and the CSD of the wall pressure field induced by the TBL.The spatial coherence of the pipe vibration field is therefore analysed for a pipe with and without flanges. This is of critical importance for applications such as non-intrusive techniques for detecting acoustic sources inside pipes, like beamforming using arrays of accelerometers. If the pipe conveys a flow, the beamforming efficiency can strongly deteriorate because of the background noise induced by the TBL, which pollutes the coherence signal between sensors.The effects that the spatial coherence could have on the beamforming results of a line of point sensors (accelerometers) and a ring of wire sensors (piezoelectric coiled wires) are also investigated in this paper.

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Section: Introductionmentioning

confidence: 99%

Spatial coherence of pipe vibrations induced by an internal turbulent flow

Maxit

Karimi

Guasch

2021

Journal of Sound and Vibration

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“…The numerical investigations showed that it could distinguish the source of the sodium-water reaction from the SGU background noise even if they had similar magnitudes. Five years later, a water experiment with mock-up tube bundles was achieved (Chikazawa and Yoshiuji, 2015). A linear array of five hydrophones was immerged in the water tank.…”

Section: Introductionmentioning

confidence: 99%

Water experiment for assessing vibroacoustic beamforming gain for acoustic leak detection in a sodium-heated steam generator

Kassab

Michel

Maxit

2019

Mechanical Systems and Signal Processing

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In an intent to improve the monitoring of steam generators, a technique based on vibration measurements is developed for the detection of a water leak into sodium. Background noise can mask the leak-induced vibrations. In order to increase the signal-to-noise ratio (SNR), a beamforming technique may be considered. In the purpose of studying the feasibility and the efficiency of this technique for the present configuration, experimental investigations have been performed on a mock-up composed by a straight cylindrical pipe coupled to a hydraulic circuit through two flanges. A sound emitter introduced in the pipe simulates the source to detect, whereas a flow speed controls the background noise vibrations. Beamforming is applied on the signals measured by an array of accelerometers externally mounted on the pipe. Two different kinds of beamforming are considered: the conventional (Bartlett) one and an advanced one based on SNR maximization (MaxSNR). After an analysis of the vibroacoustic behaviour of the mock-up, one studies the efficiency of the two beamforming treatments for narrow bands and broad bands.

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“…Beamforming techniques using an array of microphones are popular as they can increase the SNR of the leak signal, which is usually masked by the SGU background noise ( [2,6]). For instance, an acoustic leak detection method based on the so-called delay-and-sum beamformer was introduced by Chikazawa et al [3,7]. It was assumed that the background noise was uniformly distributed, unlike the sodium-reaction noise source, which was considered to be localized.…”

Section: Introductionmentioning

confidence: 99%

“…The proposed approach could differentiate the leak source from the SGU background noise even when they had very close magnitudes. The numerical results were validated by an experiment in a water tank in [7].…”

Section: Introductionmentioning

confidence: 99%