Free-Surface Profiles, Velocity and Pressure Distributions on a Broad-Crested Weir: A Physical Study

AbstractBasic experiments were conducted on a large-size broad-crested weir with a rounded corner. Detailed free-surface, velocity, and pressure measurements were performed for a range of flow conditions. The results showed the rapid flow distribution at the upstream end of the weir and next to the weir brink at large flow rates. The flow properties above the crest were analyzed taking into account the nonuniform velocity and nonhydrostatic pressure distributions. Introducing some velocity and pressure correction coefficients, it is shown that critical flow conditions were achieved above the weir crest for 0.1<x/Lcrest<1. The velocity measurements highlighted a developing boundary layer. The data differed from the smooth turbulent boundary layer theory, although the present results were consistent with earlier studies. On average, the boundary stress was approximately τo/(ρ×g×H1) 0.0015–0.0025.

[1]  Hubert Chanson,et al.  Applied Hydrodynamics: An Introduction to Ideal and Real Fluid Flows , 2009 .

[2]  J. Cunge.  Applied hydrodynamics: an introduction to ideal and real fluid flows , 2013 .

[3]  James G. Woodburn.  Tests of Broad-Crested Weirs , 1932 .

[4]  M. G. Bos.  Discharge measurement structures , 1976 .

[5]  F. Serre,et al.  CONTRIBUTION À L'ÉTUDE DES ÉCOULEMENTS PERMANENTS ET VARIABLES DANS LES CANAUX , 1953 .

[6]  Ngoc Diep Vo.  Characteristics of curvilinear flow past circular-crested weirs , 1992 .

[7]  F. Henderson.  Open channel flow , 1966 .

[8]  L. Tison.  LE DÉVERSOIR À SEUIL ÉPAIS , 1950 .

[9]  Amruthur S. Ramamurthy,et al.  Characteristics of Square‐Edged and Round‐Nosed Broad‐Crested Weirs , 1988 .

[10]  W. D. Moss,et al.  Flow separation at the upstream edge of a square-edged broad-crested weir , 1972, Journal of Fluid Mechanics.

[11]  Jane E. Sargison,et al.  Hydraulics of Broad-Crested Weirs with Varying Side Slopes , 2009 .

[12]  A J M Harrison.  THE STREAMLINED BROAD-CRESTED WEIR. , 1967 .

[13]  G W Hall.  ANALYTICAL DETERMINATION OF THE DISCHARGE CHARACTERISTICS OF BROADCRESTED WEIRS USING BOUNDARY LAYER THEORY. , 1962 .

[14]  H. Chanson,et al.  Near-critical free-surface flows: real fluid flow analysis , 2011 .

[15]  Carlos Fawer.  Etude de quelques écoulements permanents à filets courbes , 1937 .

[16]  Hubert Chanson,et al.  Characteristics of Undular Hydraulic Jumps: Experiments and Analysis , 1998 .

[17]  Willi H. Hager,et al.  Broad‐Crested Weir , 1994 .

[18]  Hubert Chanson,et al.  Minimum Specific Energy and Critical Flow Conditions in Open Channels , 2006 .

[19]  M. M. Vierhout.  On the boundary layer development in rounded broad-crested weirs with a rectangular control section , 1973 .

[20]  B. Bakhmeteff.  Hydraulics of open channels , 1932 .

[21]  H. Schlichting.  Boundary Layer Theory , 1955 .

[22]  H. Chanson Miahr,et al.  Physical modelling of the flow field in an undular tidal bore , 2005 .

[23]  Lewis Thomas Isaacs.  Effects of laminar boundary layer on a model broad-crested weir , 1981 .

[24]  Hubert Chanson,et al.  The hydraulics of open channel flow , 2004 .

[25]  Sergio Montes,et al.  Hydraulics of open channel flow , 1998 .

[26]  Hubert Chanson.  Characteristics of Undular Hydraulic Jumps , 1993 .

[27]  Hubert Chanson,et al.  Experimental measurements of velocity and pressure distributions on a large broad-crested weir , 2007 .

[28]  H. C. Miahr,et al.  Physical modelling of the flow field in an undular tidal bore , 2005 .

[29]  J. Liggett,et al.  Critical Depth, Velocity Profiles, and Averaging , 1993 .

[30]  N Rajaratnam,et al.  DISCUSSION. ANALYTICAL DETERMINATION OF THE DISCHARGE CHARACTERISTICS OF BROAD-CRESTED WEIRS USING BOUNDARY LAYER THEORY. , 1964 .

[31]  N. S. Govinda Rao,et al.  DISCHARGE CHARACTERISTICS OF WEIRS OF FINITE-CREST WIDTH , 1963 .

[32]  Larry J. Weber,et al.  The Hydraulics of Open Channel Flow: An Introduction , 2001 .