Investigating the Effect of Ramp Geometry on the Flow Characteristics Around Under Pressure Tunnel Aerator Using OpenFoam Open Source Software


Volume: 9 | Issue: 1 | Pages: 3705-3710 | February 2019 |


The flow around the ramp embedded in a pressurized tunnel is divided into various zones downstream of the ramp, including the cavity and the main zone of flow above the shear layer. Ramp angle and height are parameters that affect the flow characteristics such as cavity length, velocity, and pressure coefficient immediately downstream of the ramp. In this study, OpenFOAM open source software and RNG K-ε turbulence model were used to simulate the flow around the under pressure tunnel ramp. In order to investigate the effect of the ramp geometry on the flow in various relative air discharges 0<β<10, the range of height and the angle of the ramp as 5<θ<20 and 0.1<tr/d<0.4 were developed and simulated. The correlation coefficient between the numerical and experimental results for the relative cavity length is in the range of 0.9377≤R2≤0.9722 that indicates proper agreement between results. The result of the research shows that in both cases of fixed height of ramp and increasing ramp angle, and fixed angle of the ramp and increasing ramp height, the values of the cavity length and maximum turbulence intensity increase, and the minimum pressure values at the cavity zone bed are decreased. But in both cases, the sensitivity of the three mentioned parameters is higher than the ramp height increment.


aerator ramp, pressurized tunnel, RNG K-ε turbulence model, OpenFOAM, cavity length


Download data is not yet available.


N. L. Pinto, “Prototype aerator measurements”, in: Air Entrainment in Free-Surface Flow, pp. 115-130, Routledge, 2018 DOI:

I. R. Wood, Air Entrainment in Free-Surface Flows, CRC Press, 1991

A. J. Peterka, “The effect of entrained air on cavitation pitting. Joint Meeting Paper”, in: Proceedings: Minnesota International Hydraulic Convention, pp. 507-518, ASCE, 1953

J. M. Zhang, J. G. Chen, W. L. Xu, “Three-dimensional numerical simulation of aerated flows downstream sudden fall aerator expansion in a tunnel”, Journal of Hydrodynamics, Vol. 23, No. 1, pp. 71-80, 2011 DOI:

R. W. P. May, P. M. Brown, I. R. Willoughby, Physical and Numerical Modeling of Aerators for Dam Spillways. Hydraulics Research Report, No. SR 278, Wallingford, UK, 1991

H. T. Falvey, Cavitation in Chutes and Spillways, US Department of the Interior, Denver, Colorado, USA, 1990

H. Chanson, “Aeration of a free jet above a spillway”, Journal of Hydraulic Research, Vol. 29, No. 5, pp. 665-667, 1991 DOI:

H. Chanson, “Flow downstream of an aerator. Aerator spacing”, Journal of Hydraulic Research, Vol. 27, No. 4, pp. 519-536, 1989 DOI:

A. R. Zarrati, J. D. Hardwick, “Mathematical modelling of deaeration zone downstream of aerators”, in: Proceedings 26th Congress of IAHR, London, U.K., Vol. 2, pp. 220-225, IAHR, 1995

J. Attari, A. R., Zarrati, “The effect of nappe impact angle on aerator performance”, in: Energy and Water: Sustainable Development, pp. 601-606, ASCE, 1997

D. A. Ervine, A. R. Khan, “Turbulence measurements in an air-slot ramp aerator”, 24th IAHR World Congress, Madrid, Spain, September 9-13, 1991

H. Chanson, “Aeration and de-aeration at bottom aeration devices on spillway”, Canadian Journal of Civil Engineering, Vol. 21, pp. 404-409, 1994 DOI:

A. T. Glazov, “Calculation of the air-capturing ability of flow behind an aerator Ledge”, Hydrotechnical Construction, Vol. 18, No. 8, pp. 554-558, 1984 DOI:

J. Wu, F. Ma, H. C. Dai, “Influence of Filling Water on Air Concentration”, Journal of Hydrodynamics, Vol. 23, No. 5, pp. 601-606, 2011 DOI:

S. P. Ruan, J. H. Wu, W. W. Wu, “Hydraulic Research of Aerators on Tunnel Spillways”, Journal of Hydrodynamics, Ser. B, Vol. 19, No. 3, pp. 330-334, 2007 DOI:

M. Kavianpour, A. Toloui, A. S. al-Mu'zsoumi, “Evaluation of pressure fluctuations in downstream of aerator in lower tunnels of dams with circular sections”, National Conference on National Hydroelectric Power Plants, Tehran, Iran, June 6-7, 2002

V. V. Bhosekar, V. Y. Jothiprakash, P. B. Deolaikar, “Orifice Spillway Aerator: Hydraulic Design”, Journal of Hydraulic Engineering, Vol. 138, No. 6, pp. 563-572, 2012 DOI:

R. Narayanan, M. Manafpour, M. R. Kavianpour, “Wall pressure field in the reattaching flow past deflectors, part 2: with air injection”, in: Proceedings of the Institution of Civil Engineers-Water and Maritime Engineering, Vol. 148. No. 1, pp. 39-45, Thomas Telford Ltd, 2001 DOI:

M. Manafpour, Effects of Air Injection on the Flow Immediately Downstream of Deflectors on Spillways, PhD Thesis, Manchester University, UK, 2004

H. G. Weller, H. Jasak, C. Fureby, “A tensorial approach to computational continuum mechanics using object-oriented techniques”, Journal of Computational Physics, Vol. 12, No. 6, pp. 620-631, 1998 DOI:


How to Cite

M. Manafpour and H. Ebrahimnezhadian, “Investigating the Effect of Ramp Geometry on the Flow Characteristics Around Under Pressure Tunnel Aerator Using OpenFoam Open Source Software”, Eng. Technol. Appl. Sci. Res., vol. 9, no. 1, pp. 3705–3710, Feb. 2019.


Abstract Views: 432
PDF Downloads: 299

Metrics Information
Bookmark and Share