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Research Papers: Multiphase Flows

Characterization of Cavitation Fields From Measured Pressure Signals of Cavitating Jets and Ultrasonic Horns

[+] Author and Article Information
Sowmitra Singh

e-mail: sowmitra@dynaflow-inc.com

Georges L. Chahine

Dynaflow, Inc.,
Jessup, MD 20794

1Corresponding author.

Contributed by the Fluids Engineering Division of ASME for publication in the Journal of Fluids Engineering. Manuscript received November 19, 2012; final manuscript received April 12, 2013; published online June 6, 2013. Assoc. Editor: Olivier Coutier-Delgosha.

J. Fluids Eng 135(9), 091302 (Jun 06, 2013) (11 pages) Paper No: FE-12-1581; doi: 10.1115/1.4024263 History: Received November 19, 2012; Revised April 12, 2013

Cavitation pressure fields under a cavitating jet and an ultrasonic horn were recorded for different conditions using high frequency response pressure transducers. This was aimed at characterizing the impulsive pressures generated by cavitation at different intensities. The pressure signals were analyzed and statistics of the amplitudes and widths of the impulsive pressure peaks were extracted. Plots of number densities and cumulative numbers of peaks as functions of peak amplitude, peak width, and the power of the ultrasonic horn or the jet were generated. The analysis revealed the dominance of pulses with smaller amplitudes and larger durations at lower cavitation intensities and the increase of the amplitudes and reduction of the pulse widths at higher intensities. The ratio of the most probable peak amplitude to peak width was computed. A representative Gaussian curve was then generated for each signal using a characteristic peak amplitude and the corresponding most probable peak duration/width. This resulted in a proposed statistical representation of a cavitation field, useful to characterize cavitation fields of various intensities.

Copyright © 2013 by ASME
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References

Figures

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Fig. 8

Number density versus peak height (a) and peak width (b) for different thresholds, cavitating jet with a pressure drop of 13.8 MPa (Vjet ∼160 m/s)

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Fig. 9

Number density versus peak height (a) and peak width (b) for different jet pressures

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Fig. 7

Procedure for estimation of peak amplitude and peak width. Impulsive signals are isolated using a threshold level, peak amplitude and pulse width are then measured.

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Fig. 6

Raw signals for two power settings of the ultrasonic horn

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Fig. 5

Raw signals for two jet pressures (13.8 MPa, Vjet ∼160 m/s and 48.3 MPa, Vjet = 310 m/s)

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Fig. 4

Adaptation of high response pressure transducer with an inset for protection and minimization of spatial impulsive pressures overlap

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Fig. 3

Cavitation erosion pattern on metals created by a cavitating jet. Jet diameter = 1.17 mm. Sample distance from jet = 13.97 mm, approximate diameter of erosion pattern = 5 mm.

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Fig. 2

Cavitation pattern in the shear layer of a CaviJet® nozzle (visualizations conducted with a very large 50 mm diameter nozzle)

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Fig. 1

Ultrasonic technique eroded samples pictures. (a) Tested G32 metallic button sample; (b) eroded composite material sample from the alternative G32 method. Sample distance from horn = 0.5 mm, approximate diameter of erosion pattern = 1.3 mm.

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Fig. 10

Cumulative number of peaks versus peak amplitude for different jet pressures: curves from data fit superimposed over experimental curves

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Fig. 11

Data-fit parameters versus jet pressure: N* (a), P* (b)

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Fig. 12

Normalized plot of cumulative number of peaks versus peak amplitude for different jet pressures

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Fig. 13

Contour plot of Number Density versus peak width and peak amplitude for 13.79 MPa jet (a), 27.58 MPa jet (b), and 48.26 MPa jet (c)

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Fig. 14

Scatter plot of peak width versus peak amplitude for three different jet pressures

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Fig. 20

Cumulative number of peaks versus peak amplitude for different ultrasonic horn power settings (a): curves from data fit superimposed over experimental curves. Normalized plot of cumulative number of peaks versus peak amplitude for different power settings (b).

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Fig. 21

Most probable width/peak amplitude ratio versus the ultrasonic horn power obtained from linear fits of the scatter plots

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Fig. 22

Significant peak height versus ultrasonic horn power (a). Peak width corresponding to significant peak value versus horn power (b).

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Fig. 23

Representative (Gaussian) pressure pulses for various horn power settings

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Fig. 18

Significant peak height versus jet pressure (a). Peak width corresponding to significant peak value versus jet pressure (b).

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Fig. 19

Representative (Gaussian) pressure pulses for various jet pressures obtained from impulsive pressure identification and using the procedure illustrated in Fig. 16

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Fig. 15

Representative Gaussian pressure pulse (a). An experimentally recorded pressure pulse (Δpjet = 27.58 MPa) fitted using a representative Gaussian pressure pulse.

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Fig. 16

Determination of most probable width/peak amplitude ratio from the linear fit of scatter plot. Dots in this figure represent all impulsive pressure peaks detected in the jet during a recording period of 1 s.

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Fig. 17

Most probable width/peak amplitude ratio versus jet pressure obtained from the linear fits of scatter plots

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