Submergence Factors for Hydraulic Turbines
Publication: Journal of Energy Engineering
Volume 115, Issue 2
Abstract
The elevation of a hydroelectric turbine above or below tailwater is based on hydraulic model studies to determine the critical sigma, defined as the ratio of barometric pressure plus submergence depth at which cavitation commences divided by the rated head. Turbine model studies are undertaken by manufacturers to determine the sigma value for each model runner. This information is properietary and is never published. Consultants and utilities need to know the value of sigma during feasibility studies to establish unit setting and power plant layout. For this information, reference is usually made to published data relating sigma to other turbine parameters such as the specific speed. However, this method can result in erroneous settings, since there is a range of sigma values for each specific speed. This paper develops an alternative approach based on an analysis of over 80 recently installed turbines, wherein the turbine submergence is shown to be a function of the turbine throat velocity, the number of runner blades or buckets, the atmospheric pressure and the water temperature. The equation is applicable to Kaplan, propellor and Francis turbines with either horizontal or vertical axes. From this equation, another is derived to determine the turbine throat diameter as a function of the desired setting above or below tailwater.
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References
1.
Anderson, E., et al. (1980). “Hydro in northern Saskatchewan—Charlot.” Trans., Canadian Electrical Association, Vol. 19, Part 2.
2.
Chasma feasibility study. (1987). Vol. 2, Water Power Development Authority, Pakistan, India, 14–16.
3.
Cotillon, J. (1981). “World's bulb turbines.” Water Power and Dam Constr., Sept., 42–43.
4.
Coulson, D., et al. (1984). “La Grande 2, Canada, solving a severe cavitation problem.” Water Power and Dam Constr., 36(1), 20–24.
5.
Desbaillets, J. A., and Kanger, F. (1976). “Giant 820.000 hp turbines for Grand Coulee.” Trans., Canadian Electrical Association, Vol. 15, Part 2.
6.
Douma, A. (1985). “The Annapolis tidal power project.” Trans., Canadian Electrical Association, Vol. 24, Part 2.
7.
Fazalare, R. W. (1985). “Bulb turbine selection for the main canal project.” Water Power, Oct., 33–37.
8.
Gordon, J. L. (1983). “Powerhouse concrete quantity estimates.” Can. J. Civ. Engrg., 10(2), 271–286.
9.
Grigera, R. (1988). “Aswan high dam project, turbine modernization—hydro '88 conference papers.” Water Power and Dam Constr., 423–445.
10.
Hammond, G., et al. (1989). “Manic 5.p.a.—additional capacity of turbines and generators.” Trans., Canadian Electrical Association, Vol. 28, Part 2.
11.
Kawano, M., et al. (1986). “The 86.5 MW Kaplan turbines at Nipawin.” Trans., Canadian Electrical Association, Vol. 25, Part 2.
12.
Knapps, R. T., and Hollander, A. (1948). “Laboratory investigations of the mechanism of cavitation.” Trans., ASME, July, 419–435.
13.
Lugaresi, A., and Massa, A. (1987). “Designing Francis turbines: trends in the last decade.” Water Power and Dam Constr., 39(11), 23–28.
14.
Miller, J., et al. (1988). “Uprating the Laufenberg power station with ten Straflo units—hydro '88 conference papers.” Water Power and Dam Constr., 462–479.
15.
Moraes, J., et al. (1981). “Turbines for Itiapu.” Water Power and Dam Constr., 33(12), 36–41.
16.
Moraes, J., et al. (1982). “Turbines for Itiapu.” Water Power and Dam Constr., 34(1), 28–33.
17.
Pawlikewich, W., and Sinclair, J. P. (1976). “Trend to zero cavitation in hydraulic turbine operation.” Trans., Canadian Electrical Association, Vol. 15, Part 2.
18.
Perreault, H. C. (1970). “Turbines and generators for the Churchill Falls power project.” Trans., Canadian Electrical Association, Vol. 9, Part 2.
19.
“Prevention and reduction of cavitation and pitting in hydraulic turbines.” (1949). Current trends no. 11, Allis‐Chalmers Manufacturing Co., Milwaukee, Wis., 1–12.
20.
Schweiger, F., and Gregori, J. (1987). “Developments in the design of Kaplan turbines.” Water Power and Dam Constr., 39(11), 16–20.
21.
“Small hydro plants with standardized s turbines.” Brochure No. 21.04.30 KB 84.60, Bell Engineering Works Ltd.
22.
The La Grande River hydroelectric complex. (1988). Vol. 1, Societe d'energie de la Baie James, Montreal, Quebec, Canada.
23.
Stewart, W. A., and Wayne, W. W. (1974). “Rock Island to use bulb turbines.” J. of Power Div., ASCE, 100(2), 175–190.
24.
Strub, W. R. (1978). “Moxoto Kaplan turbines.” Trans., Canadian Electrical Association, Vol. 17, Part 2.
25.
Sturge, L. G., and McKechnie, A. L. (1981). “The upper Salmon development.” Trans., Canadian Electrical Association, Vol. 20(2).
26.
Technical bulletin. (1988). Vevey Engineering Works, Vevey, Switzerland, 1–67.
27.
Thicke, R. H., and Bakar, L. T. (1973). “Plant layout and turbine design—Bighorn.” Trans., Canadian Electrical Association, Vol. 2, Part 2.
28.
Thicke, R. H., and Gordon, J. L. (1974). “Turbine selection for the Kainji extension.” Trans., Canadian Electrical Association, Vol. 13, Part 2.
29.
Ueda, T. (1983). “Large capacity bulb units in Japan.” Water Power, Mar., 19–24.
30.
Vandenber, G. (1984). “Mechanical aspects of Revelstoke project.” Trans., Canadian Electrical Association, Vol. 23, Part 2.
31.
Vatcher, T. R. (1981). “Cavitation experience at the Bay d'Espoir generating station.” Trans., Canadian Electrical Association, Vol. 20(2).
32.
Voith, S. “Turbines in standardized sizes.” Brochure t2520e, Heidenheim, West Germany.
33.
Warnick, C. C. (1984). Hydropower Engineering. Prentice‐Hall, Inc. Englewood Cliffs, N.J.
34.
Wilcox, F. L., et al. (1981). “Hinds Lake development.” Trans., Canadian Electrical Association, Vol. 10, Part 2.
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Copyright © 1989 ASCE.
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Published online: Aug 1, 1989
Published in print: Aug 1989
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