Experimental Study of the Breakup of a Free-Falling Turbulent Water Jet in Air
Publication: Journal of Hydraulic Engineering
Volume 142, Issue 10
Abstract
An experimental study on the breakup of a turbulent round-water jet in still air with a nozzle Reynolds number of 145,600 and Weber number of 10,400 is reported. The visual structure of the falling water jet was recorded by a high-speed camera, and the characteristics of the falling jet were investigated. As the jet travelled from the nozzle, initial surface disturbances grew, and the lateral oscillation of the jet surface was amplified. The jet thickness initially increased and then decreased because of the combined effects of lateral turbulence fluctuation and gravitational acceleration. The amplitude of the surface disturbance grew in an exponential form. Based on the averaged transverse-water distribution, the water jet spreading rate was found to vary between 0.5 and 1.8%, and the decay of the jet water core had an average value of 0.7%. The onset of jet breakup was found at a distance of approximately 100 times of the nozzle diameter. A theoretical model was developed for predicting the onset of jet breakup by comparing the dynamic air pressure with the restraining surface tension pressure. The velocity of the water drops released after breakup was measured and found to be approximately 0.8 times of the local jet velocity.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The writers gratefully acknowledge financial support from the China Scholarship Council, the Natural Sciences and Engineering Research Council (NSERC) of Canada, and China Water Pollution Control Program (Project No. 2011ZX07301-004).
References
Bhunia, S. K., and Lienhard, J. H. (1994). “Surface disturbance evolution and the splattering of turbulent liquid jets.” J. Fluids Eng., 116(4), 721–727.
Camino, G. A., Zhu, D. Z., and Rajaratnam, N. (2015). “Flow observations in tall plunging flow dropshafts.” J. Hydraul. Eng., 06014020.
Chen, T.-F., and Davis, J. R. (1964). “Disintegration of a turbulent water jet.” J. Hydraul. Div., 90(1), 175–206.
Dai, Z., Chou, W., and Faeth, G. M. (1998). “Drop formation due to turbulent primary breakup at the free surface of plane liquid wall jets.” Phys. Fluids, 10(5), 1147–1157.
Donaldson, C. D., Snedeker, R. S., and Margolis, D. P. (1971). “A study of free jet impingement. Part 2. Free jet turbulent structure and impingement heat transfer.” J. Fluid Mech., 45(03), 477–512.
Ervine, D. A., and Falvey, H. T. (1987). “Behaviour of turbulent water jets in the atmosphere and in plunge pools.” Proc. Inst. Civ. Eng., 83(3), 295–314.
Ervine, D. A., Mckeogh, E. J., and Elsawy, E. M. (1980). “Effect of turbulence intensity on the rate of air entrainment by plunging water jets.” Proc. Inst. Civ. Eng., 69(2), 425–445.
Grant, R. P., and Middleman, S. (1966). “Newtonian jet stability.” AIChE J., 12(4), 669–678.
Hoyt, J. W., and Taylor, J. J. (1977a). “Turbulence structure in a water jet discharging in air.” Phys. Fluids, 20(10), S253–S257.
Hoyt, J. W., and Taylor, J. J. (1977b). “Waves on water jets.” J. Fluid Mech., 83(1), 119–127.
Huang, Z. (2012). “A numerical study of air entrainment in turbulent free surface flows.” Ph.D. thesis, Sichuan Univ., Chengdu, China.
Kim, J., Moin, P., and Moser, R. (1987). “Turbulence statistics in fully developed channel flow at low Reynolds number.” J. Fluid Mech., 177, 133–166.
Ma, Y. Y., Zhu, D. Z., and Rajaratnam, N. (2016). “Air entrainment in a tall plunging flow dropshaft.” J. Hydraul. Eng., in press.
MATLAB [Computer software]. MathWorks, Natick, MA.
Miesse, C. C. (1955). “Correlation of experimental data on the disintegration of liquid jets.” Ind. Eng. Chem., 47(9), 1690–1701.
Morozumi, Y., and Fukai, J. (2004). “Growth and structures of surface disturbances of a round liquid jet in a coaxial airflow.” Fluid Dyn. Res., 34(4), 217–231.
Ng, C., Sankarakrishnan, R., and Sallam, K. A. (2008). “Bag breakup of nonturbulent liquid jets in crossflow.” Int. J. Multiphase Flow, 34(3), 241–259.
Pan, Y., and Suga, K. (2006). “A numerical study on the breakup process of laminar liquid jets into a gas.” Phys. Fluids, 18(5), 052101.
Portillo, J. E., Collicott, S. H., and Blaisdell, G. A. (2011). “Measurements of axial instability waves in the near exit region of a high speed liquid jet.” Phys. Fluids, 23(12), 124105.
Rayleigh, L. (1879). “On the stability, or instability, of certain fluid motions.” Proc. London Math. Soc., s1-11(1), 57–72.
Sallam, K. A., Dai, Z., and Faeth, G. M. (2002). “Liquid breakup at the surface of turbulent round liquid jets in still gases.” Int. J. Multiphase Flow, 28(3), 427–449.
Schmocker, L., Pfister, M., Hager, W. H., and Minor, H. (2008). “Aeration characteristics of ski jump jets.” J. Hydraul. Eng., 90–97.
Schweitzer, P. H. (1937). “Mechanism of disintegration of liquid jets.” J. Appl. Phys., 8(8), 513–521.
Urban, A. L., Gulliver, J. S., and Johnson, D. W. (2008). “Modeling total dissolved gas concentration downstream of spillways.” J. Hydraul. Eng., 550–561.
Weber, C. Z. (1931). “Zum Zerfall eines Flussigkeitsstrahles.” Zeitschrift für Angewandte Mathematik und Mechanik, 11(2), 136–154.
Wygnanski, I., and Fiedler, H. (1968). Some measurements in the self preserving jet, Cambridge University Press, Cambridge, U.K.
Xiao, F., Dianat, M., and McGuirk, J. J. (2013). “LES of turbulent liquid jet primary breakup in turbulent coaxial air flow.” Int. J. Multiphase Flow, 60(2), 103–118.
Xu, G., and Antonia, R. (2002). “Effect of different initial conditions on a turbulent round free jet.” Exp. Fluids, 33(5), 677–683.
Zhang, W., and Zhu, D. Z. (2015). “Far-field properties of aerated water jets in air.” Int. J. Multiphase Flow, 76, 158–167.
Zhang, W., Zhu, D. Z., Rajaratnam, N., Edwini-Bonsu, S., Fiala, J., and Pelz, W. (2015). “Use of air circulation pipes in deep dropshafts for reducing air induction into sanitary sewers.” J. Hydraul. Eng., 04015092.
Information & Authors
Information
Published In
Journal of Hydraulic Engineering
Volume 142 • Issue 10 • October 2016
Copyright
© 2016 American Society of Civil Engineers.
History
Received: Nov 19, 2015
Accepted: Apr 4, 2016
Published online: Jun 9, 2016
Published in print: Oct 1, 2016
Discussion open until: Nov 9, 2016
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.