Circular Plunging jet : acoustic and physical characteristics

AIR ENTRAINMENT AT A CIRCULAR PLUNGING JET: PHYSICAL AND ACOUSTIC CHARACTERISTICS - Internet Database

by Hubert CHANSON
School of Civil Engineering, The University of Queensland, Brisbane QLD 4072, Australia
(Email: h.chanson@uq.edu.au, Internet : http://www.uq.edu.au/~e2hchans/index.html)

and Richard MANASSEH
formerly CSIRO-DBCE, PO Box 56, Highett QLD 3190, Australia (Email: richard.manasseh@dbce.csiro.au, Internet : http://fluids.mel.dbce.csiro.au/~richman/home.html)
Internet database : http://www.uq.edu.au/~e2hchans/photo.html

Summary
Plunging jet flows are employed to produce some gas-liquid interface, typically to dissolve gas in liquid. They are bottlenecks in minerals and food processing, biotechnology and waste-water treatment. The mechanisms of air bubble entrainment by circular plunging jets are discussed in the light of new experimental evidence. The results were obtained in the developing flow region of 25-mm diameter water jets (see Photograph). Void fraction distributions follow closely an advective diffusion theory, and the bubble count rate distribution exhibit consistently a maximum in the inner side of the void fraction peak. Acoustic measurements of the bubbly flow were further conducted with void fractions up to 40% (CHANSON and MANASSEH 2003).
The article is complemented by a website database for two-dimensional plunging jets: http://www.uq.edu.au/~e2hchans/data/jfe97.html. Further experiments were further performed to study air entrainment in seawater, salty freshwater and freshwater. Results were presented by CHANSON et al. (2002,2006).

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Experimental apparatus
The experimental apparatus consists of a vertical circular jet issuing from a 0.025-m diameter nozzle. The receiving channel is 0.3-m wide and 1.8-m deep with glass walls (See Figure). Underwater acoustics was measured with a B&K hydrophone type 8103 connected to a B&K charge amplifier type 2635. The signal was recorded on Digital Audio Tape (DAT) which digitised the signal at 44.1 kHz, thereby implying an alias frequency around 22 kHz..

Acoustic Recording
Three data sets were selected from one run (Run RM3, see table below). The experiments were conducted with a 5-mm free-jet length. The hydrophone was located 20-mm below the free-surface. Each file is a VAW format that may be played with Media Player or Sound Recorder applications (Windows 95 or later), or Quicktime.

V1	x1	x - x1	File
m/s	m	m
0.94	0.005	0.02	Bubbles5.wav
3.1	0.005	0.02	Bubbles6.wav
5.0	0.005	0.02	Bubbles3.wav

At low jet velocities (V1 = 0.94 /s), a small number of distinct high-pitch sounds are heard corresponding to the entrainment of individual bubbles. The high-pitch associated with high frequency sound is characteristic of a small bubble size. (The sound frequency is basically inversely proportional to the bubble size.)
In the second recording, the louder noise characterises a higher bubble entrainment rate. The combination of high-pitch and louder "rumble" indicates the entrainment of both small individual bubbles as well as larger air bubbles/packets.
A the largest flow velocity (V1 = 5 m/s), the bubble noise is louder and covers a wide range of frequencies. This is characteristic of a stronger air bubble entrainment rate.

References

BRATTBERG, T., and CHANSON, H. (1998). "Air Entrapment and Air Bubble Dispersion at Two-Dimensional Plunging Water Jets." Chemical Engineering Science, Vol. 53, No. 24, Dec., pp. 4113-4127 (ISSN 0009-2509) (Download PDF file) (PDF file at UQeSpace). Errata: 1999, Vol. 54, No. 12, p. 192 (Download PDF file).
CHANSON, H. (1997). "Air Bubble Entrainment in Free-Surface Turbulent Shear Flows." Academic Press, London, UK, 401 pages (ISBN 0-12-168110-6).
CHANSON, H. (2004). "Air Entrainment in Hydraulic Engineering." in "Fluvial, Environmental & Coastal Developments in Hydraulic Engineering", Balkema, Leiden, The Netherlands, Proc. International Workshop on State-of-the-Art Hydraulic Engineering, 16-19 Feb. 2004, Bari, Italy, M. MOSSA, Y. YASUDA and H. CHANSON Ed., pp. 17-63 (ISBN 04 1535 899 X). (PDF file at UQeSpace)
CHANSON, H. (2009). "Turbulent Air-water Flows in Hydraulic Structures: Dynamic Similarity and Scale Effects." Environmental Fluid Mechanics, Vol. 9, No. 2, pp. 125-142 (DOI: 10.1007/s10652-008-9078-3) (ISSN 1567-7419 [Print] 1573-1510 [Online]). (PDF file at UQeSpace)
CHANSON, H., AOKI, S., and HOQUE, A. (2002). "Similitude of Air Bubble Entrainment and Dispersion in Vertical Circular Plunging Jet Flows. An Experimental Study with Freshwater, Salty Freshwater and Seawater." Coastal/Ocean Engineering Report, No. COE02-1, Dept. of Architecture and Civil Eng., Toyohashi University of Technology, Japan. (Download PDF files)
CHANSON, H., AOKI, S., and HOQUE, A. (2002). "Scaling Bubble Entrainment and Dispersion in Vertical Circular Plunging Jet Flows: Freshwater versus Seawater." Proc. 5th Intl Conf. on Hydrodynamics ICHD 2002., Tainan, Taiwan, H.H. HWUNG, J.F. LEE & K.S. HWANG Editors, pp. 431-436. (Download PDF File)
CHANSON, H., AOKI, S., and HOQUE, A. (2002). "Similitude of Air Entrainment at Vertical Circular Plunging Jets." Proc. 2002 ASME Joint US-European Fluids Eng. Conf., FEDSM-2002, Montréal, Canada, Paper FEDSM2002-31024, 6 pages (CD-ROM) (ISBN 0-7918-3600-2). (download PDF file)
CHANSON, H., AOKI, S., and HOQUE, A. (2004). "Physical Modelling and Similitude of Air Bubble Entrainment at Vertical Circular Plunging Jets." Chemical Engineering Science, Vol. 59, No. 4, pp. 747-754 (ISSN 0009-2509). (PDF file at UQeSpace) (Download PDF file)
CHANSON, H., AOKI, S., and HOQUE, A. (2006). "Bubble Entrainment and Dispersion in Plunging Jet Flows: Freshwater versus Seawater." Journal of Coastal Research, Vol. 22, No. 3, May, pp. 664-677 (DOI: 10.2112/03-0112.1) (ISSN 0749-0208). (PDF file at UQeSpace)
CHANSON, H., and BRATTBERG, T. (1998). "Air Entrainment by Two-Dimensional Plunging Jets : the Impingement Region and the Very-Near Flow Field." Proc. 1998 ASME Fluids Eng. Conf., FEDSM'98, Washington DC, USA, June 21-25, Keynote paper, Paper FEDSM98-4806, 8 pages (CD-ROM) (ISBN 0 7918 1950 7). (PDF file at UQeSpace)
CHANSON, H., and MANASSEH, R. (2003). "Air Entrainment Processes in a Circular Plunging Jet. Void Fraction and Acoustic Measurements." Journal of Fluids Engineering, Trans. ASME, Vol. 125, No. 5, Sept., pp. 910-921 (ISSN 0098-2202). (Download PDF file) (PDF file at UQeSpace)
CUMMINGS, P.D., and CHANSON, H. (1997). "Air Entrainment in the Developing Flow Region of Plunging Jets. Part 1 Theoretical Development." Jl of Fluids Eng., Trans. ASME, Vol. 119, No. 3, pp. 597-602 (ISSN 0098-2202). (download PDF file)
CUMMINGS, P.D., and CHANSON, H. (1997). "Air Entrainment in the Developing Flow Region of Plunging Jets. Part 1 Theoretical Development." Journal of Fluids Engineering, Transactions ASME, Vol. 119, No. 3, pp. 597-602 (ISSN 0098-2202). ( download PDF file) (PDF file at UQeSpace)
CUMMINGS, P.D., and CHANSON, H. (1997). "Air Entrainment in the Developing Flow Region of Plunging Jets. Part 2 : Experimental." Journal of Fluids Engineering, Transactions ASME, Vol. 119, No. 3, pp. 603-608 (ISSN 0098-2202). (download PDF file) (PDF file at UQeSpace) {Databank} MANASSEH, R., and CHANSON, H. (2001). "Void-Fraction and Acoustic Characteristics of Gas Bubbles Entrained by a Circular Plunging Jet." Proc. 4th Intl Conf. Multiphase Flow, ICMF'01, New Orléans, USA, Paper 347, 12 pages (CD-ROM). [download PDF file]

Related bibliography
BERTOLA, N.J., WANG, H., and CHANSON, H. (2018), "Air Bubble Entrainment, Breakup and Interplay in Vertical Plunging Jets." Journal of Fluids Engineering, ASME, Vol. 140, No. 9, Paper 091301, 13 pages (DOI: 10.1115/1.4039715) (ISSN 0098-2202). (PDF file) (Preprint at UQeSpace)
CHANSON, H. (1995). "Air Bubble Entrainment in Free-surface Turbulent Flows. Experimental Investigations." Report CH46/95, Dept. of Civil Engineering, University of Queensland, Australia, June, 368 pages (ISBN 0 86776 611 5). (PDF Version at EprintsUQ) (Click to order Bound Copy) {Databank}
CHANSON, H,. (2002). "An Experimental Study of Roman Dropshaft Operation : Hydraulics, Two-Phase Flow, Acoustics." Report CH50/02, Dept of Civil Eng., Univ. of Queensland, Brisbane, Australia, 99 pages (ISBN 1864996544). ( Download PDF files http://www.uq.edu.au/~e2hchans/ch5002.zip [2.5 Mb]) (PDF version at EprintsUQ) Order Hard Copy
CHANSON, H. (2003). "Experimental Investigation of Dropshaft Hydraulics: Two-Phase Flow and Acoustics." Proc. 30th IAHR Biennial Congress, Thessaloniki, Greece, J. GANOULIS and P. PRINOS Ed., Vol. B, pp. 353-360 (ISBN 960-243-594-1). (Download PDF File)
CHANSON, H. (2004). "Understanding Air-Water Mass Transfer at Rectangular Dropshafts." Journal of Environmental Engineering and Science, NRC, Vol. 3, No. 5, pp. 319-330 (ISSN 1496-256X). (PDF file at UQeSpace) (Download PDF file)
CHANSON, H. (2004). "Hydraulics of Rectangular Dropshafts." Journal of Irrigation and Drainage Engineering, ASCE, Vol. 130, No. 6, pp. 523-529 (ISSN 0733-9437). (PDF file at UQeSpace) (Download PDF file)
CHANSON, H. (2007). "Air Entrainment Processes in Rectangular Dropshafts at Large Flows." Journal of Hydraulic Research, IAHR, Vol. 45, No. 1, pp. 42-53 (ISSN 0022-1686). (PDF file at UQeSpace)
CHANSON, H. (2013). "Hydraulics of Aerated Flows: Qui Pro Quo?" Journal of Hydraulic Research, IAHR, Invited Vision paper, Vol. 51, No. 3, pp. 223-243 (DOI: 10.1080/00221686.2013.795917) (ISSN 0022-1686). (Postprint at UQeSpace) (PDF file)
CHANSON, H., and BRATTBERG, T. (1997). "Experimental Investigations of Air Bubble Entrainment in Developing Shear Layers." Report CH48/97, Dept. of Civil Engineering, University of Queensland, Australia, Oct., 309 pages (ISBN 0 86776 748 0). (Order a Hard Copy) (PDF Version at EprintsUQ)
MURZYN, F., and CHANSON, H. (2008). "Experimental Assessment of Scale Effects Affecting Two-Phase Flow Properties in Hydraulic Jumps." Experiments in Fluids, Vol. 45, No. 3, pp. 513-521 (DOI: 10.1007/s00348-008-0494-4) (ISSN 0723-4864). (PDF file at UQeSpace)

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About Prof Hubert CHANSON
Hubert CHANSON is a Professor in Civil Engineering, Hydraulic Engineering and Environmental Fluid Mechanics at the University of Queensland, Australia. His research interests include design of hydraulic structures, experimental investigations of two-phase flows, applied hydrodynamics, hydraulic engineering, water quality modelling, environmental fluid mechanics, estuarine processes and natural resources. He has been an active consultant for both governmental agencies and private organisations. His publication record includes over 850 international refereed papers and his work was cited over 3,900 times (WoS) to 14,900 times (Google Scholar) since 1990. His h-index is 33 (WoS), 36 (Scopus) and 60 (Google Scholar), and he is ranked among the 150 most cited researchers in civil engineering in Shanghai’s Global Ranking of Academics. Hubert Chanson is the author of twenty books, including "Hydraulic Design of Stepped Cascades, Channels, Weirs and Spillways" (Pergamon, 1995), "Air Bubble Entrainment in Free-Surface Turbulent Shear Flows" (Academic Press, 1997), "The Hydraulics of Open Channel Flow : An Introduction" (Butterworth-Heinemann, 1st edition 1999, 2nd editon 2004), "The Hydraulics of Stepped Chutes and Spillways" (Balkema, 2001), "Environmental Hydraulics of Open Channel Flows" (Butterworth-Heinemann, 2004), "Tidal Bores, Aegir, Eagre, Mascaret, Pororoca: Theory And Observations" (World Scientific, 2011) and "Applied Hydrodynamics: an Introduction" (CRC Press, 2014). He co-authored two further books "Fluid Mechanics for Ecologists" (IPC Press, 2002) and "Fluid Mechanics for Ecologists. Student Edition" (IPC, 2006). His textbook "The Hydraulics of Open Channel Flows : An Introduction" has already been translated into Spanish (McGraw-Hill Interamericana) and Chinese (Hydrology Bureau of Yellow River Conservancy Committee), and the second edition was published in 2004. In 2003, the IAHR presented him with the 13th Arthur Ippen Award for outstanding achievements in hydraulic engineering. The American Society of Civil Engineers, Environmental and Water Resources Institute (ASCE-EWRI) presented him with the 2004 award for the Best Practice paper in the Journal of Irrigation and Drainage Engineering ("Energy Dissipation and Air Entrainment in Stepped Storm Waterway" by Chanson and Toombes 2002) and the 2018 Honorable Mention Paper Award for "Minimum Specific Energy and Transcritical Flow in Unsteady Open-Channel Flow" by Castro-Orgaz and Chanson (2016) in the ASCE Journal of Irrigation and Drainage Engineering. Hubert Chanson edited further several books, including the recent monograph "Energy Dissipation in Hydraulic Structures" (Chanson 2015, IAHR Monograph, CRC Press). He chaired the Organisation of the 34th IAHR World Congress held in Brisbane, Australia between 26 June and 1 July 2011. He chaired the Scientific Committee of the 5th IAHR International Symposium on Hydraulic Structures held in Brisbane in June 2014. He chairs the Organisation of the 22nd Australasian Fluid Mechanics Conference in Brisbane, Australia on 6-10 December 2020.
His Internet home page is http://www.uq.edu.au/~e2hchans. He also developed a gallery of photographs website {http://www.uq.edu.au/~e2hchans/photo.html} that received more than 2,000 hits per month since inception.