Effect of Nozzle Diameter and Falling Height on the Dynamic Pressure Coefficient of Vertical Free Water Jets

Document Type : Research Paper

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Abstract

Stilling basins are constructed at the downstream of dam spillways to dissipate the excess energy of the spilled flows. The turbulent flow velocity converts to the dynamic pressure due to impact of flow pockets with the basin’s walls and bed.  Experiments were conducted using a pressure transmitter system to measure the resulted dynamic pressures from the impact of a series of rounded non-submerged jet on a flat plate. The analysis of data showed that a 18% moderate decrement in nozzle diameter caused a 14% moderate increment in the dynamic pressure coefficient and a 34% moderate decrement in jet drop length caused an approximately 13% increment in the dynamic pressure coefficient. Nevertheless, variations of the dynamic pressure coefficient with the increment of nozzle discharge had no regular trend and it began to decrease after reaching a maximum point.

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References

Beltaos S and Rajaratnam N, 1974. Impinging circular turbulent jets. Journal of Hydraulic Division, ASCE. 100: 1313-1328.
Beltaos S and Rajaratnam N, 1976. Plan of turbulent impinging jets. Journal of Hydraulic Research.35(3):29-59
Bollaert E and Schleiss A, 2003. Scour of rock due to the impact of plunging high velocity jets Part II. Journal of Hydraulic Research, IAHR 41)5(: 465-480
Castillo ELG, Puertas J and Dolz J, 1999. Discussion: Pressure fluctuations on plunge pool floors (Ervine DA, Falvey HT and Withers WA). Journal of Hydraulic Research 37)2(:272-277.
Castillo ELG, 2002. Parametrical analysis of the ultimate scour and mean dynamic pressures at plunge pools. International Workshop on Rock Scour due to High Velocity Jets. Federal Polytechnic University of Lausanne.
Castillo ELG, Puertas J and Dolz J, 2004. Discussion: Scour of rock due to the impact of plunging high velocity jets Part I: A state-of-the art review. (Bollaert E. and Schleiss A). Journal of Hydraulic Research. 41(5): 451-464.
Castillo ELG, 2006. Aerated jets and pressure fluctuation in plunge pools. 7th Int. Conf. on Hydro science and Engineering (ICHE). 10Sep– 13Sep. Philadelphia, USA.
Castillo ELG, 2007. Pressures characterization of undeveloped and developed jets in shallow and deep pool. 32nd Congress of the International Association of Hydraulic Engineering & Research(IAHR). 1 – 6 July 2007. Venice, Italy.
Cola r, 1966. Diffusion of the vertical water jet in a plane basin at a limited energy, ). Journal of Hydraulic Research.11:649-667.
Davies JT, 1972. Turbulence Phenomena. Academic press, New York And London.
Ervine DA and Falavey HT, 1987. Behavior of  turbulent jets In atmosphere and in plunge  pools. Part 2. 83:295-314. proceeding of the institution of the civil Engineering. Glasgow, Scotland.
Ervine DA, Falavey HT and Withersw,1997. Pressure fluctuation on plunge pool floors. Journal of Hydraulic Research ,IAHR. 35(2): 491-513
Kerman Nejad  J, Fathi-Moghadam M, Lashkarara B and Haghighipour S, 2011. Dynamic pressure of Filip Bucket Jet. World Aapplied Sciences Journal.12(8):1165-1171
Lencaster A, 1961. Free overflow spillway. Engineering and design principle. National Lab. for Civil Engrs. Report No. 174. Portugal, Lisbon.
Water and Soil Science
Volume 24, Issue 4 - Serial Number 4
February 2015
Pages 185-195

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