Reservoir Destratification via Mechanical Mixers
Publication: Journal of Hydraulic Engineering
Volume 119, Issue 4
Abstract
Destratification techniques are often used to improve water quality in reservoirs. The majority of investigations have concentrated on the use of bubble aerators; however, an interesting alternative is the use of mechanical mixing systems consisting of a large propeller immersed in the water column. A laboratory study of such a system was used to examine the efficiency of energy conversion from mechanical energy to buoyancy flux as a function of impeller diameter, the speed of rotation, and the degree and type of stratification. The results were shown to depend on a generalized Froude number with the peak efficiency of energy conversion as high as 12%. A direct scaling mechanism enabling the results found in the laboratory model to be applied to a prototype situation was achieved via the application of derived scaling parameters. A simple design methodology for prototype versions of mechanical mixing systems based on this study is suggested.
Get full access to this article
View all available purchase options and get full access to this article.
References
1.
Asaeda, T., and Imberger, J. (1992). “Structures of bubble plumes in linearly stratified environments.” J. Fluid Mech.
2.
Baines, W. D., and Leitch, A. M. (1992). “The destruction of a stratified density distribution by a bubble plume.” J. Hydr. Engrg., 118(4), 559–577.
3.
Brown, I. K. (1986). Review of the application of aeration/destratification techniques in Australian surface water storages. Dept. Local Govt., Queensland, Australia.
4.
Busnaina, A. A., and Lilley, D. G. (1983). “Computer prediction of local destratification near low‐level release structures of reservoirs.” Fluids Eng. Div., ASME, 105, 65–70.
5.
Busnaina, A. A., Lilley, D. G., and Moretti, P. M. (1981). “Prediction of local destratification of lakes.” J. Hydr. Div., ASCE, 3, 259–272.
6.
Cherkasky, V. M. (1980). Pumps fans compressors. Mir Publishers, Moscow, Russia.
7.
Davis, J. M. (1980). “Destratification of reservoirs—A design approach for perforated pipe compressed air systems.” Water Services, 84, 497–504.
8.
Ditmars, J. D., and Cederwall, K. (1974). “Analysis of air‐bubble plumes.” Proc., 14th Conf. Coastal Engrg., London, 2209–2226.
9.
Eck, B. (1973). “Fans—design and operation of centrifugal, axial‐flow and cross‐flow fans.” Vertilstoren, R. S. Azad and D. R. Scott, eds., Pergamon Press, Germany.
10.
Fischer, H. B., List, E. J., Koh, R. C. Y., Imberger, J., and Brooks, N. H. (1979). Mixing in inland and coastal waters, Academic Press, New York, N.Y.
11.
Fortuin, J. M. H. (1960). “Theory and applications of two supplementary methods of constructing density gradient columns.” J. Polymer Sci., 44, 505–515.
12.
Fox, E. A., and Gex, V. E. (1955). Presented at Detroit Meeting, A.I.Ch.E.
13.
Head, M. J. (1983). “The use of miniature four‐electrode conductivity probes for high resolution measurement of turbulent density or temperature variations in salt‐stratified water flows,” PhD dissertation, Univ. of California, San Diego, Calif.
14.
Henderson‐Sellers, B. (1984). Engineering limnology. Pitman Publishers Ltd., London, England.
15.
Hussain, N. A., and Narang, B. S. (1984). “Simplified analysis of air‐bubble plumes in moderately stratified environments.” J. Heat Trans., 106, 543–551.
16.
Imberger, J., and Ivey, G. N. (1991). “On the nature of turbulence in a stratified fluid. Part 2: Application to lakes.” J. Phys. Oceanography, 21(5), 659–680.
17.
Imberger, J., and Patterson, J. C. (1990). “Physical limnology.” Advances in applied mechanics, T. Wu, ed., 303–475.
18.
Irwin, W. H., Symons, J. M., and Robeck, G. G. (1966). “Impoundment destratification by mechanical pumping.” Proc. J. Sanitary Eng. Div., ASCE, 92, 21–40.
19.
Ivey, G. I., and Imberger, J. (1991). “On the nature of turbulence in a stratified fluid. Part 1: The energetics of mixing.” J. Phys. Oceanography, 21(5), 650–658.
20.
Labus, T. L., and Symons, E. P. (1972). “Experimental investigation of an axisymmetric free jet with an initially uniform velocity profile.” NASA TN D‐6783, Nat. Aeronautics and Space Administration (NASA), Washington, D.C.
21.
Lemckert, C. J., and Imberger, J. (1992). “Design methodology for bubble plume destratification systems.” ED742CL, Ctr. for Water Res., Univ. of Western Australia, Nedlands, Australia.
22.
McDougall, T. J. (1978). “Bubble plumes in stratified environments.” J. Fluid Mech., 85, 655–672.
23.
Morton, B. R., Taylor, G. I., and Turner, J. S. (1956). “Turbulent gravitational convection from maintained and instantaneous sources.” Proc. R. Soc. London Ser. A 234, 1–23.
24.
Oldshue, J. Y. (1983). Fluid mixing technology. McGraw‐Hill, New York, N.Y.
25.
Oldshue, J. Y., Hirschland, H. E., and Gretton, A. T. (1956). “Blending of lowviscosity liquids with side‐entering mixers.” Chem. Engrg. Progress, 52(11), 481–484.
26.
Osborne, W. C. (1977). Fans. 2nd Ed., N. S. Billington and E. Ower, eds.
27.
Papanicolaou, P. N., and List, E. J. (1988). “Investigations of round vertical turbulent buoyant jets.” J. Fluid Mech., 195, 341–391.
28.
Patterson, J. C., and Imberger, J. (1989). “Simulation of bubble plume destratification systems in reservoirs.” Aquatic Sci., 59(1), 3–18.
29.
Ridley, J. E., Cooley, P., and Steel, J. A. P. (1966). “Control of thermal stratification in Thames Valley reservoirs.” Proc. Soc. for Water Treatment and Examination, 15(14), 225–244.
30.
Robinson, K. M., Garton, J. E., and Punnett, R. E. (1982). “Localized destratification at Lake Texoma.” J. Envir. Engrg. Div., ASCE, 108(4).
31.
Schladow, S. G. (1991). “A design methodology for bubble plume destratification systems.” Environmental hydraulics, Lee and Cheung, eds., A. A. Balkema, Rotterdam, the Netherlands, 173–178.
32.
Schladow, S. G. (1992). “Bubble plume dynamics in a stratified medium and the implications for water quality amelioration in lakes.” Water Resour. Res., 28, 313–321.
33.
Stepanoff, A. J. (1948). Centrifugal and axial flow pumps—Theory, design and application. John Wiley & Sons, New York, N.Y.
34.
Suter, P. J., and Kilmore, G. (1990). “Mechanical mixers: An alternative destratification technique. Myponga Reservoir, South Australia, Water.” J. Australian Water & Wastewater Association.
35.
Toetz, D. W. (1981). “Effects of whole lake mixing on water quality and phytoplankton.” Water Res., 15.
36.
Tolland, H. G. (1977). “Destratification/aeration in reservoirs.” Tech. Report TR50, Water Res. Ctr., England.
37.
Wallis, R. A. (1983). Axial flow fans and ducts—Design and practise. John Wiley & Sons, Toronto, Canada.
Information & Authors
Information
Published In
Copyright
Copyright © 1993 American Society of Civil Engineers.
History
Received: Mar 31, 1992
Published online: Apr 1, 1993
Published in print: Apr 1993
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.