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


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.


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.


Main Subjects

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Volume 41, Issue 2
June 2018
Pages 93-105
  • Receive Date: 01 March 2016
  • Revise Date: 13 December 2016
  • Accept Date: 23 January 2017
  • First Publish Date: 22 June 2018