عنوان مقاله [English]
نویسندگان [English]چکیده [English]
The water surface profiles on spillway are important for design of free board and spillway training wall height. The engineers have used physical modeling to design these kinds of structures, Considering that the scale effect in the spillway modeling, leads to the different measured data between model and prototype, in this study, an experimental model based on Garmi-Chay Mianeh dam spillway was designed in three 1:100, 1:75, and 1:50 scales. Next, the water surface profile on spillway crest measured in seven discharges and compared with
basic scale of (1:50), the percentage of water level difference on the crest calculated in two
physical models with 1:100 and 1:75 scales. Results and observations revealed that in
due to the effect of viscosity and surface tension the difference of water level in the scale of 1:100 and 1:75 was 18.4% and 15.6% respectively, relative to the base scale. The larger discharge, water level on spillway increases, leads to decrease viscosity and surface tension effects. For the difference in water level in the scale of 1:100 and 1:75 was 5.8% and 4.8% respectively relative to the base scale. In this study, viscosity and surface tension effects is stated with correction equation (K'), that was functions of Reynolds and Weber numbers. With the ogee spillway modeling the effect of viscosity in Reynolds numbers larger than 3.1*104 and the effect of tension surface in Weber numbers larger than 270 can be neglected and by extrapolation prototype results from model studies can be obtained.
Boes, R. M. 2000. Scale effects in modeling two-phase stepped spillway flow. International Workshop on Hydraulics of Stepped Spillways. Zürich. Switzerland.
Boes, R. M. and Hager, W. H. 2003. Two-phase flow characteristics of stepped spillways. J. Hydraul. Eng. ASCE. 129, 661-670.
Castro-Orgaz, O. and Hager, W. H. 2014. Scale effects of round-crested weir flow. J. Hydraul. Res. 52(5): 653-665.
Chanson, H. 2004. The Hydraulics of Open Channel Flow: An Introduction. 2nd Edition. Elsevier Butterworth-Heinemann. London.
Chanson, H. 2008. Physical modelling, scale effects and self-similarity of stepped spillway flows. Proceeding of the World Environmental and Water Resources Congress. May 12-16. Honolulu. Hawaii. United States.
Chanson, H. and Chachereau, Y. 2013. Scale effects affecting two phase flow properties in hydraulic jump with small inflow Froude number. Exp. Therm. Fluid Sci. 45, 234-242.
Crookston, B. M. 2010. Labyrinth Weirs. Ph. D. Thesis. Department of Civil and Environmental Engineering. Utah State University.
Ettema, R., Arndt, R., Roberts, P. and Wahl, T. 2005. Hydraulic Modeling: Concept and Practice. Translater: Shamsaie, A. and Sarng, A. Sharif University of Technology. Institute of Scientific Publications. Tehran. (in Persian)
Fais, L. M. C. F. and Genovez, A. I. B. 2008. Discharge rating curve and scale effects correction in morning glory spillways. Proceedings of 16th IAHR-APD Congress and 3rd Symposium of IAHR-ISHS. Oct. 20-23. Hohai University. Nanjing. China.
Felder, S. and Chanson, H. 2009. Turbulence dynamic similarity and scale effects in high-velocity
free-surface flows above a stepped chute. Exp. Fluid. 47, 1-18.
Fox, R. W., McDonald, A. T. and Pritchard, Ph. J. 2011. Introduction to Fluid Mechanics (19th Ed.). Translater: Poosti, B. Academic Pub. Tehran. Iran. (in Persian)
Gonzalez, C. A. and Chanson, H. 2004. Scale effects in moderate slope stepped spillways experimental studies in air-water flows. Proceeding of the 8th National Conference on Hydraulics in Water Engineering. July 13-16. Australia.
Gonzalez, C. A. and Chanson, H. 2005. Experimental study of turbulence manipulation in stepped spillway. implications on flow resistance in skimming flows. Proceeding of the IAHR Congress. Sep. 11-16. Seoul. Korea.
Hamedi, M. H. 2002. Hydraulic Open Channel. Vol. I. Khaje-Nasir-Toosi University Press. Tehran. Iran. (in Persian)
Heller, V. 2011. Scale effects in physical hydraulic engineering models. J. Hydraul. Res. 49(3): 293-306.
Hosseini, S. M. and Abrishami, J. 2011. Hydraulic Open Channel. 20th Edition. Emam-Reza University Press. Mashhad. Iran. (in Persian)
Johnson, M. C. and Savage, B. M. 2006. Physical and numerical comparison of flow over ogee spillway in the presence of tailwater. J. Hydraul. Eng. ASCE. 132(12): 1353-1357.
Murzyn, F. and Chanson, H. 2008. Experimental assessment of scale effects affecting two-phase flow properties in hydraulic jumps. Exp. Fluid. 45, 513-521.
Najmaei, M. 1994. Hydraulic Applications. Vol. I. University of Science and Technology Press. Tehran. Iran. (in Persian)
Pfister, M., Battisacco, E., De Cesare, G. and Schleiss, A. J. 2013. Scale effects related to the rating curve of cylindrically crested piano key weirs. Proceeding of the 2nd International Workshop on Labyrinth and Piano Key Weirs. Nov. 20-22. Paris. France.
Pfister, M. and Chanson, H. 2014 Two phase air-water flows: scale effects in physical modeling. J. Hydrodyn. 26, 291-298.
Ranga-Raju, K. G. and Asawa, G. L. 1977. Viscosity and surface tension effects on weir flow. J. Hydraul. Div. ASCE. 103(10): 1227-1231.
Tanner, W. F. 1982. Rooster tail. Beaches and Coastal Geology. Part of the Series Encyclopedia of Earth Science. Available at: http://link.springer.com. 702-703.
Woolbright, R. W. 2006. Hydraulic performance evaluation of RCC stepped spillways with sloped converging training Walls. B. Sc. Biosystems Engineering. Oklahoma State University. Stillwater. Oklahoma.