Amirkabir Journal of Civil Engineering

Amirkabir Journal of Civil Engineering

Investigation Discharge Coefficient and Stage-discharge Equation for Broad-Crested Weirs Including the Effects of Sloping Crest and Upstream and Downstream ramps

Document Type : Research Article

Authors
Bahram Nourani 1
Hadi Arvanaghi 2
Farzin Salmasi 2
1 Ph.D Candidate, University of Tabriz / Department of Water Engineering
2 Associate Professor, University of Tabriz / Department of Water Engineering
10.22060/ceej.2023.18920.6999
Abstract
Weirs are one of the types of hydraulic structures in water projects that with different cross section have been widely used as flow measuring, controlling and regulating of upstream water surface for turnouts devices, in conveyance water canals or body of dams. In this study, the hydraulic characteristics of flow over broad-crested weirs including the effects of different configurations of sloping crest and upstream and downstream ramps using of finite volume method (FVM) by the ANSYS FLUENT software was investigated. Numerical simulations were validated by experimental results. The results showed that discharge coefficient (Cd) for the BCW-UR-PSC and BCW-UDR-NSC weirs are higher than the BCW-UDR-HC weir. The average increase of Cd in BCW-UDR-NSC respect to BCW-UDR-HC in such a way that θ=-4.76° and- 9.46° is 18% and 25%, while the average increase of Cd in the BCW-UDR-PSC respect to the BCW-UDR-HC for same condition (θ=+4.76° and+9.46°) is 10% and 18%. It was found that both of the BCW-UDR-NSC and BCW-UDR-PSC, the Cd increases with steeper of the crest slope (or increasing θ). Also, the results showed that for BCW-UDR-PSC, value of Cd is 0.35≤Cd≤.47, however for the BCW-UDR-NSC, values of Cd are between 0.42≤Cd≤0.48. This shows that the Cd is affected by the sloping of the crest in such a way that negative slope respect positive slope has more impact in this increase. The average increase of the Cd in BCW-UDR-NSC respect to the BCW-UDR-PSC is approximately 8%.
Keywords
Broad-Crested Weir
Discharge Coefficient
Finite Volume Method
Upstream and Downstream Ramp
Sloping Crest
Subjects
  1. S.G. Rao, D. Muralidhar, Discharge characteristics of weirs of finite-crest width, Houille Blanche, 18(5( (1963( 537 – 545.
  2. Goodarzi, J. Farhoudi, N. Shokri, Flow characteristics of rectangular broad-crested weirs with sloped upstream face, Journal of Hydrology and Hydromechanics, 60(2( (2012( 100-187.
  3. Farhoudi, H.S. Alami, Slope effect on discharge efficiency in rectangular broad crested weir with sloped upstream face, Int. J. Civ. Eng., 3 (2005( 58–65.
  4. E. Sargison, A. Percy, Hydraulics of broad-crested weirs with varying side slopes, Journal of irrigation and drainage engineering, 135(1( (2009( 115-118.
  5. Abbaspour, M. Abdolahpour, F. Salmasi, Numerical Simulation of Flow over Rectangular Broad-crested Weir with Upstream and Downstream Side Slopes Using Fluent Model, Water and soil science, 23(4( (2013( 266276 (In Persian(.
  6. Simsek, M.S. Akoz, N.G. Soydan, Numerical validation of open channel flow over a curvilinear broadcrested weir, Progress in Computational Fluid Dynamics, 364-378 (2016( (6(16.
  7. Major, M. Orfanus, Z. Zachoval, Flow over Broadcrested weir inflow by approach shaft-numerical model, Stavební obzor, 30(1( (2021( 260-267.
  8. M. Shaymaa, M.M. Huda, M.K. Rasul, N.N. Thameen, A.A. Nadhir, Flow over broad-crested weirs: comparison of 2d and 3d models, Civ. Eng. Archit. , 11(1( (2017( 769-779.
  9. Haun, N.R.B. Olsen, R. Feurich, Numerical modeling of flow over trapezoidal broad-crested weir, Eng. Appl. Comp. Fluid, 5 (2011( 397–405.
  10. A. Nadheer, M.H. Alaa, Numerical simulation for flow over a broad-crested weir using FLOW-3D program, Civil Engineering and Architecture 10(5( (2022( 21572171.
  11. H. Azimi, N. Rajaratnam, Z.Z. David, Discharge characteristics of weirs of finite crest length with upstream and downstream ramps, J. Irrig. Drain Eng, (2013( 75-83.
  12. H. Azimi, N. Rajaratnam, Z.Z. David, Submerged Flows over rectangular weirs of finite crest length, J. Irrigation and Drainage. Eng, 140(5((2014(.
  13. Aksoy, M. Doğan, Experimental investigation of the approach angle effects on the discharge efficiency for broad crested weirs, Anadolu University Journal of Science and Technology, Applied Sciences and Engineering, 17(2( (2016( 279-286.
  14. Jiang, M. Diao, H. Sun, Y. Ren, Numerical modeling of flow over a Rectangular Broad-Crested Weir with a Sloped Upstream Face, journal of water, 10(11(:1663 (2018(.
  15. Malekzadeh, F. Salmasi, J. Abraham, H. Arvanaghi, Numerical investigation of the effect of geometric parameters on discharge coefficients for broad-crested weirs with sloped upstream and downstream faces, Appl Water Sci, 12(110( (2022.(
  16. T. Zerihun, Free flow and discharge characteristics of trapezoidal-shaped weirs Fluids, 5(4( (2020(.
  17. Nourani, H. Arvanaghi, F. Salmasi, A novel approach for estimation of discharge coefficient in broad-crested weirs based on Harris Hawks Optimization algorithm Flow Measurement and Instrumentation, 79(101916( (2021(
  18. Salmasi, F. Nahrain, A.T. Aghdam, Prediction of discharge coefficients for broad-crested weirs using expert systems, Amirkabir J. Civil Eng., 54(12( (2023( 4435-4458 (In Persian(.
  19. H. Hager, M. Schwalt, Broad-crested weir, J. Irrigation and Drainage. Eng, 120:1(13( (1994( 13–26.
  20. W. Hirt, B.D. Nichols, Volume of fluid (VOF( method for the dynamics of free boundaries, J. Comput. Phys., 39 (1981( 201–225.
  21. Bayon, D. Valero, Performance assessment of OpenFOAM and FLOW-3D in the numerical modeling of a low Reynolds number hydraulic jump, Environ. Model. Softw., 80 (2016( 322-335.
  22. P. Toro, F. Bombardelli, J. Paik, Detached eddy simulation of the no narrated skimming flow over a stepped spillway, J. Hydraul. Eng., 143 (2017.(
  23. Nourani, F. Salmasi, H. Arvanaghi, F. Rezaei, Undular flow conditions and discharge coefficients in rectangular broad-crested weirs, Amirkabir J. Civil Eng., 54(1) (2022) 125-140 (In Persian(.
  24. A. Aysegul, D. Mustafa, Experimental investigation of the approach angle effect on the discharge efficiency for broad-crested weirs, Sci. Technol, 17. (2016) (279–682)
Amirkabir Journal of Civil Engineering
Volume 55, Issue 10
January 2024
Pages 1933-1956