Detection of ultrasonic cavitation based on low-frequency analysis of acoustic signal

Brabec, Kamil; Mornstein, Vojtěch

doi:10.2478/s11535-007-0013-2

Cited by 14 publications

(13 citation statements)

References 8 publications

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“…FFT spectral levels of harmonics, sub and ultra-harmonics of sound pressure waveform, for (a) 250 W, (b) 360 W and (c) 600 W electric power. streams, confirming previous suggestions of Brabec and Mornstein (2007) concerning to tests performed with water. This behavior also confirmed the findings of Abramov (1998) concerning to the relation between the sub-harmonic (f/2) amplitude and cavitation intensity.…”

Section: Resultssupporting

confidence: 90%

The combined effect of melt stirring and ultrasonic agitation on the degassing efficiency of AlSi9Cu3 alloy

et al. 2009

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The purpose of this work was the development of a reliable technique to evaluate the intensity of acoustic cavitation during degassing of aluminium melts and to use it to select the optimum processing time for an envisaged degassing efficiency. A high sensitivity piezoelectric disk type device was used as a sensing feedback in water and liquid AlSi9Cu3 alloy. The signal acquisition and processing was carried out on a dedicated LabVIEW ® based application which allowed real-time monitoring of the piezoelectric sensor's data and ultrasonic parameters. Standard Fast Fourier Transform was applied to obtain the dominant frequencies, as well as the sub and ultra-harmonics. It was found that the amplitude of the FFT sub-harmonic (f/2) was the best indicator to evaluate the process degassing efficiency, and it could be used to select the optimal processing time, independently of other variables. The developed methodology was applied to several AlSi9Cu3 melts, and validated by measuring the final alloy densities and the volume fraction of porosities, revealing that it is an efficient, fast and cost effective technique to evaluate the degassing treatment of aluminium alloys. Experimental curves of AlSi9Cu3 alloy degassing efficiency as a function of f/2 amplitude are presented for different degassing times.

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Section: Resultssupporting

confidence: 90%

The combined effect of melt stirring and ultrasonic agitation on the degassing efficiency of AlSi9Cu3 alloy

et al. 2009

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“…Between 270 and 300 W electric power, a sudden increase in the sub-harmonic amplitude was detected, and a change in the curve slope was clearly identified. This means that the cavitation threshold was reached and for higher values a well-developed cavitation regime was established, which was visually confirmed by a sudden increase in the amount of cavitation bubbles and the development of acoustic streams, confirming previous suggestions of Brabec and Mornstein (2007) concerning to tests performed with water. This behavior also confirmed the findings of Abramov (1998) concerning to the relation between the sub-harmonic (f/2) amplitude and cavitation intensity.…”

Section: Resultssupporting

confidence: 87%

Evaluation of ultrasonic aluminium degassing by piezoelectric sensor

Puga¹,

Barbosa²,

Gabriel³

et al. 2011

Journal of Materials Processing Technology

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a b s t r a c tThe purpose of this work was the development of a reliable technique to evaluate the intensity of acoustic cavitation during degassing of aluminium melts and to use it to select the optimum processing time for an envisaged degassing efficiency.A high sensitivity piezoelectric disk type device was used as a sensing feedback in water and liquid AlSi9Cu3 alloy. The signal acquisition and processing was carried out on a dedicated LabVIEW ® based application which allowed real-time monitoring of the piezoelectric sensor's data and ultrasonic parameters. Standard Fast Fourier Transform was applied to obtain the dominant frequencies, as well as the sub and ultra-harmonics. It was found that the amplitude of the FFT sub-harmonic (f/2) was the best indicator to evaluate the process degassing efficiency, and it could be used to select the optimal processing time, independently of other variables.The developed methodology was applied to several AlSi9Cu3 melts, and validated by measuring the final alloy densities and the volume fraction of porosities, revealing that it is an efficient, fast and cost effective technique to evaluate the degassing treatment of aluminium alloys. Experimental curves of AlSi9Cu3 alloy degassing efficiency as a function of f/2 amplitude are presented for different degassing times.

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“…8, it is clear that the sub-harmonic (d) significantly decreases when the distance to the acoustic radiator increases. Besides the intensity of the FFT subharmonic (d) increase in areas close to the acoustic radiator, the intensity of the FFT ultra-harmonics (m) seems to stabilize which is a consequence of a well-developed cavitation regime as suggested by (Ref 11,23). According to Fig.…”

Section: Effect Of the New Degassing Approach On The H 2 Contentmentioning

confidence: 67%

A New Approach to Ultrasonic Degassing to Improve the Mechanical Properties of Aluminum Alloys

Puga

Barbosa

Teixeira

et al. 2014

J. of Materi Eng and Perform

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Ultrasonic degassing of liquid metals has been studied over the last years, but it has been limited to laboratorial scale experiments of low volumes of melt. In this work, the combined effect of acoustic cavitation with metal agitation induced by the mechanical vibration of the ultrasonic radiator itself was studied, using a specially designed low frequency mechanical vibrator coupled to the ultrasonic degassing unit. Liquid motion in water was characterized by high speed digital Photron-FastCam APX RS video camera and Laser Doppler Anemometry to select the most favorable US and mechanical vibrator frequencies to induce suitable water stirring. Selected parameters were used to degas 10 L of AlSi9Cu3(Fe) alloy. A suitable piezoelectric sensor was used to measure sound pressure at different distances from the sonotrode to identify the zone of higher acoustic activity. Results have shown that melt stirring significantly improves US degassing efficiency (since it is possible to achieve almost the aluminum alloy theoretical density after 3 min processing time) which contributed to increase the tensile properties of the alloy.

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Detection of ultrasonic cavitation based on low-frequency analysis of acoustic signal

Cited by 14 publications

References 8 publications

The combined effect of melt stirring and ultrasonic agitation on the degassing efficiency of AlSi9Cu3 alloy

The combined effect of melt stirring and ultrasonic agitation on the degassing efficiency of AlSi9Cu3 alloy

Evaluation of ultrasonic aluminium degassing by piezoelectric sensor

A New Approach to Ultrasonic Degassing to Improve the Mechanical Properties of Aluminum Alloys

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