Numerical Simulation of Aerator ramp influence at Bed and Spillway’s Wall Duct on Vacuum Creation Index using Flow 3D Model

Document Type : Research Paper

Authors

1 Assistant professor ,Department of Hydraulic Structures, Young Researchers and Elite Club, Dezful Branch, Islamic Azad University, Dezful, Iran.

2 Department of hydraulic Structures, Dezful Branch, Islamic Azad University, Dezful, Iran

3 Young Researchers and Elite Club, Mahabad Branch, Islamic Azad University, Mahabad, Iran.

4 Professor, Department of Civil Engineering, University of Tabriz, Tabriz, Iran.

Abstract

In places where the flow velocity is high, due to the unevenness of the spillway bed , the streamlines  are separated from the bed, and at the downstream area, the pressure drop occurs and ultimately leads to the destruction of the spillway bed (Raesi, 2011). Jonson (1963) showed that, if the vacuum is formed inside the vortex core, the initial value of the vacuum should be less than or equal to one. Ohern and Katz (1986) have shown in their research that the beginning of the initial vacuum is in the three-dimensional structure inside the nucleus and not in the nuclei of the circuits. Savage and Johnson (2006) have found that a numerical model is useful for determining the flow rate and flow pressure by comparing the numerical and physical model of the flow over the Ojee spillway. Zhang, Wu and Dong (2010), with the help of the model made in the Hydraulic Laboratory of the University of Zhijiang, have studied the effect of air mixture in flow on the surface pressure and vacuum, and showed  to have a positive effect on air concentration. ShafaiBajestan and NasrEsfahani (2014) investigated the  cavitation phenomenon at the stilling basin with a rough bed and an abrupt drop. In this study, factors affecting the index of cavitation like velocity, pressure and  the amount of air into the stream in five states of without aeration, with ramps on the bed, with ramps on the bed and wall duct, with a ramp in the walls, and also with a ramp on the bedand the wall was examined.

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References

1-    Aydin, M.C. and Ozturk, M., 2009. Verification and validation of a computational fluid dynamics (CFD) model for air entrainment at spillway aerators. Canadian Journal of Civil Engineering, 36(5), pp.826-836.
 
2-    DehdarBehbahani, p., FathiMoghaddam, M., Hosseini, h. and Fazelipour, Sh., 2011. Investigation of the Cavitation phenomenon during a jet projectile using a FLOW-3D model. 10th Iranian Hydraulic Conference. University of Guilan, Guilan, Iran. (In Persian (.
 
3-    Dong, Z., Wu, Y. and Zhang, D., 2010. Cavitation characteristics of offset-into-flow and effect of aeration. Journal of hydraulic research, 48(1), pp.74-80.
 
4-    Erfanain-Azmoudeh, M.H. and Kamanbedast, A.A., 2013. Determine the appropriate location of aerator system on Gotvandoliadam’s spillway using Flow 3D. American-Eurasian Journal of Agricultural & Environmental Sciences, 13(3), pp.378-383.
 
5-    Johnson, M.C. and Savage, B.M., 2006. Physical and numerical comparison of flow over ogee spillway in the presence of tailwater. Journal of hydraulic engineering, 132(12), pp.1353-1357.
 
6-    Johnson, V., 1963. Mechanics of cavitation. Journal of the Hydraulics Division, 89(3), pp.251-275.
 
7-    Katz, J. and O’hern, T.J., 1986. Cavitation in large scale shear flows. Journal of fluids engineering, 108(3), pp.373-376.
 
8-    Kermani, E.F., Barani, G.A. and Ghaeini-Hessaroeyeh, M., 2013. Investigation of cavitation damage levels on spillways. World Applied Sciences Journal, 21(1), pp.73-78.
 
9-    Khosrojerdy, A. And Parhizgar, V.Z., 2012. Investigating the Effect of Away Ramp Dimension on the Negative Impact of Shaft Overflow of Siahaz and Dagashan Dam. In 11th Iranian Hydraulic Conference, University of Orumieh, Orumieh, Iran. (In Persian (.
 
10- Mahdavi Meymand, A., Ahadiyan, J. 2015. Evaluation of Statistical, Empirical, Neural Networks and Neural – Fuzzy Techniques for Estimation of Spillway Aerators. Irrigation Sciences and Engineering, 38(3), pp. 51-61.(In Persian (.
 
11- Nasr Esfahani, M., Shafai-Bajestan, M. 2014. Investigation of Cavitation at the Roughened Bed of Abrupt Drop Stilling Basin.  Journal of Hydraulics, 8(2), pp. 29-40. (In Persian(.
 
12- Raisey, Z., 2011. The phenomenon of Cavitation. Zagros-Tehran.(In Persian (.
 
13- Tabbara, M., Chatila, J. and Awwad, R., 2005. Computational simulation of flow over stepped spillways. Computers & structures, 83(27), pp.2215-2224.
 
14- Vosoughifar, H., Abdollahi, R., Shabanipour. Z., 2005. Location of cavitation in the weir heights. Aria-Zamin.(In Persian (.
 
Zandi, Y., 2014. Cavitation in overflow. Islamic Azad University-Tabriz.(In Persian
Irrigation Sciences and Engineering
Volume 41, Issue 2
June 2018
Pages 93-105

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History

  • Receive Date: 01 March 2016
  • Revise Date: 13 December 2016
  • Accept Date: 23 January 2017
  • Publish Date: 22 June 2018

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