Investigating the Scouring Rate in Plunge Pools Resulting from Impinging Jets With and Without Aeration

Document Type : Research Paper

Authors

1 M.Sc. Graduate, Department of Civil Engineering, Jundi-Shapur University of Technology, Dezful, Iran.

2 Assistant Professor, Department of Civil Engineering, Jundi-Shapur University of Technology, Dezful, Iran

3 Professor, Department of Hydrology and Water Resources, Shahid Chamran University of Ahvaz, Iran.

Abstract

draining the flood of enormous dams and transmitting the procedure to the downstream is one of the important issues regarding hydraulic structures. Plunge pools are the main structures to dissipate the high rate of energy. The amount of energy at an outlet jet depends on various parameters such as the dropping height, the thickness of the jet, and other environmental conditions. Local erosion in plunge pools with alluvial beds is a complex phenomenon and determining the geometric features of the scour hole is really difficult. The outlet flow mixes with the turbulence factor and hits the bed of the plunge pools with a semi-perpendicular condition. Therefore, the present study was conducted to determine the scour which was caused by inlet air along the middle water jet on the bottom of the plunge pools. Xu et al. (2004) tested the aeration effects on the scouring caused by the falling jet and obtained a small relationship between the percentage of air jet density and the relative scour depth. The results informed that aeration affects the shape of the scour hole and essentially reduces the scour depth. Manso et al. (2004) investigated the interaction of the geometric shape of the submerged pond with rocky bedding on the rate of diffusion of the falling jet. They tested various diameters of jets,5.5, 11 and 16.5 times the diameter of falling jet, on the smooth and rough beds to investigate the dynamic pressures with frequencies between 1 to 2 KHZ. Their findings showed that the geometric shape of the pond has a direct impact on the jet diffusion rate. Duarte et al. (2015) studied the effects of air inlet to jet on the dynamical pressure on the floor of the submerged pond. They increased the jet's velocity to 22 m/s. The final results showed that the air inlet to the jet led to a decline in the total pressure on the floor of the pond.

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References

1-    Armaghani, A., 2013. Experimental Study of the effect of pre-aerated jet on plunge pool scour depth. Master's thesis. Jundi-Shapur University of Thechnology, Dezful, Iran(In Persian).
 
2-    Bin, A.K., 1984, September. Air entrainment by plunging liquid jets. In Proceedings of the IAHR Symposium on scale effects in modeling hydraulic structures (pp. 5-5).
 
3-    Bohrer, J.G., Abt, S.R. and Wittler, R.J., 1998. Predicting plunge pool velocity decay of free falling, rectangular jet. Journal of hydraulic engineering, 124(10), pp.1043-1048.
 
4-    Bormann, N.E. and Julien, P.Y., 1991. Scour downstream of grade-control structures. Journal of Hydraulic Engineering, 117(5), pp.579-594.
 
5-    Canepa, S. and Hager, W.H., 2003. Effect of jet air content on plunge pool scour. Journal of hydraulic engineering, 129(5), pp.358-365.
 
6-    Clarke, F.R.W., 1962. The action of submerged jets on moveable material (Doctoral dissertation, Imperial College London (University of London).
 
7-    Duarte, R., Schleiss, A.J. and Pinheiro, A., 2015. Influence of jet aeration on pressures around a block embedded in a plunge pool bottom. Environmental Fluid Mechanics, 15(3), pp.673-693.
 
8-    Ervine, D.A., 1976. The entrainment of air in water. International Water Power and Dam Construction, 28(12), pp.27-30.
 
 
9-    Mason, P.J., 1989. Effects of air entrainment on plunge pool scour. Journal of Hydraulic Engineering, 115(3), pp.385-399.
 
10- Manso, P.E.D.R.O., Bollaert, E.F.R. and Schleiss, A.J., 2004, November. Influence of rock scour geometry on dynamic pressures due to jet impact. In 2nd Int. Conf. on Scour and Erosion (pp. 14-17).
 
11- Robinson, K.M., 1989. Stress distribution at an overfall. Transactions of the ASAE, 32(1), pp.75-0080.
 
12- Rouse, H., 1940. Criteria for Similarity in the Transportation of Sediment. University of Iowa Studies in Engineering, 20, pp.33-49.
 
13- Xu, W., Deng, J., Qu, J., Liu, S. and Wang, W., 2004. Experimental investigation on influence of aeration on plane jet scour. Journal of Hydraulic Engineering, 130(2), pp.160-164.
 
14- Van de Sande, E., 1981. Air entrainment by plunging water jets (Doctoral dissertation, TU Delft, Delft University of Technology).
Irrigation Sciences and Engineering
Volume 41, Issue 1
May 2018
Pages 85-97

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History

  • Receive Date: 12 June 2016
  • Revise Date: 05 October 2017
  • Accept Date: 01 November 2016
  • Publish Date: 21 April 2018

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