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					                                                                                Rectangular sharp crested weirs - Francis Formula




                                                     Sharp Edged Rectangular Weir                                      Sharp edged Rectangular Weir                   Sharp edged Rectangular Weir
                                                Full width - modular flow                                          With end contractions - modular flow        With end contractions -modular flow
                                                Approach velocity neglected                                        Approach velocity neglected                 Including approach velocity
                                                                  Model 3.1.1                                                         Model 3.1.2                                   Model 3.1.3

                                                     Rectangular sharp crested weir                                     Rectangular sharp crested weir                Rectangular sharp crested weir
                                                                      3                                                                  3                                              3
                                                Discharge          (m /s)      0.600                               Discharge           (m /s)      0.250       Discharge             (m /s)      0.250
                                                d/s water level   (mAOD)       0.700                               d/s water level    (mAOD)       0.900       d/s water level      (mAOD)       0.900
                                                Weir crest level  (mAOD)       1.000                               Weir crest level   (mAOD)       1.000       Weir crest level     (mAOD)       1.000
Drowning Neglected




                                                Width b             (m)        3.646                               Width b              (m)        1.000       Width b                (m)        1.000

                                                Discharge Coefficient Cd         0.623                             Discharge Coefficient Cd           0.623    Discharge Coefficient Cd              0.623
                                                Head over weir        (m)        0.200                             Head over weir                     0.275    Head Over Weir           (m)          0.265
                                                Upstream WL        (mAOD)        1.200                             Number of contractions               2      Number of contractions                  0
                                                                    Freefall     0.300                             Effective width be      (m)        0.945    Effective width be       (m)          1.000
                                                Assumptions                                                        Head over weir          (m)        0.275
                                                Approach velocity neglected                                        Error in head over weir            0.000                 Upstream Channel
                                                Suppressed rectangular weir                                        Upstream WL          (mAOD)        1.275    Invert               (mAOD)           0.000
                                                           Cd = 0.623                                                                    Freefall     0.100    Width                  (m)            2.000
                                                                                                                   Assumptions                                 Depth                (mAOD)           1.265
                                                                                                                                                                                        2
                                                                                                                   Approach velocity neglected                 Area                   (m )           2.529
                                                                                                                   End contractions considered                 Velocity v            (m/s)           0.099
                                                                                                                                  Cd = 0.623                   alpha                                   1
                                                                                                                                                                2
                                                                                                                                                               v /2g                     (m)         0.000
                                                                                                                                                               Total head over weir                  0.265

                                                                                                                                                               Qf                                     0.251
                                                                                                                                                               Error in discharge                    -0.001
                                                                                                                                                               Upstream WL             mAOD           1.265
                                                                                                                                                                                       Freefall       0.100
                                                                                                                                                               Assumptions
                                                                                                                                                               Approach velocity considered
                                                                                                                                                               End contractions considered
                                                                                                                                                                              Cd = 0.623




                                                     Sharp edged Rectangular Weir                                      Sharp edged Rectangular Weir                 Sharp crested Rectangular Weir
                                                full width - partially drowned                                     End contractions - partially drowned                         Model 3.1.6
                                                Approach velocity neglected                                        Approach velocity neglected                 Approach velocity neglected
                                                                    Model 3.1.4                                                      Model 3.1.5

                                                     Rectangular sharp crested weir                                      Rectangular sharp crested weir                Rectangular sharp crested weir
                                                Discharge           (m 3/s)    0.300                               Discharge             (m3/s)     0.100      Discharge               (m3/s)     0.300
                                                d/s water level    (mAOD)      1.050                               d/s water level     (mAOD)       1.050      d/s water level        (mAOD)      1.050
                                                Weir crest level   (mAOD)      1.000                               Weir crest level    (mAOD)       0.900      Weir crest level       (mAOD)      1.000
Drowning Considered




                                                Width b               (m)      1.000                               Width b                (m)       1.000      Width b                   (m)      1.000
                                                Discharge Coefficient Cd       0.623                               Discharge Coefficient Cd         0.623      Discharge Coefficient Cd           0.623
                                                Extent of drowning h2 (m)      0.050                               Extent of drowning h2 (m)        0.150      Extent of drowning h2 (m)          0.050
                                                Head over weir        (m)      0.304                               Head over weir         (m)       0.196      Head over weir            (m)      0.316
                                                Qf                  (m 3/s)    0.308                               Number of contractions             2        Number of contractions                 2
                                                Qs                  (m 3/s)    0.300                               Effective width be     (m)    0.9608918     Effective width be        (m)      0.937
                                                Error in Q                       0.000                             Qf                    (m3/s)       0.153
                                                Upstream WL         mAOD         1.304                             Qs                    (m3/s)       0.100                 Upstream Channel
                                                                    Freefall     -0.050                            Error in Q                         0.000    Invert               (mAOD)        0
                                                Assumptions                                                        Upstream WL           mAOD         1.096    Width                  (m)         2
                                                If weir fully submerges and ceases to                                                    Freefall     -0.150   Depth                (mAOD)      1.316
                                                be a control, then results inapplicable                            Assumptions                                 Area                   (m2)   2.63273722
                                                                                                                   If weir fully submerges and ceases to       Velocity v            (m/s)      0.114
                                                             Cd = 0.623                                            be a control, then results inapplicable     alpha                              1
                                                                                                                                                               v2/2g                  (m)       0.001
                                                                                                                                 Cd = 0.623                    Total head over weir             0.317

                                                                                                                                                               Qf                       (m3/s)        0.308
                      Notes                                                                                                                                    Qs                       (m3/s)        0.300
                         1 Input data to cells with blue type                                                                                                  Error in discharge                     0.000
                         2 Calcluation cells in SI units.                                                                                                      Upstream WL              mAOD          1.316
                         3 Use 0.623 as default weir discaharge coefficient (see reference below)                                                                                       Freefall     -0.050
                         4 These models are of varying complexity. For outline design purposes the model 3.1.1 should be adequate.                             Assumptions
                         5 The bright green cell marked freefall refers to the freeboard between the crest of the weir and the downstream water level.         If weir fully submerges and ceases to
                            Where this number is negative the weir is drowned.                                                                                 be a control, then results inapplicable
                         6 Qf is the discharge assuming no drowning
                         7 Qs is the corrected discharge to account for the drowning                                                                                           Cd = 0.623
                         8 The cell "Width b" refers to the weir crest length
                      File

                      Reference
                      Featherstone R.E. & Nalluri C. Civil Engineering Hydraulics pp 66
                      Featherstone R.E. & Nalluri C. Civil Engineering Hydraulics pp 70 (drowning)
                      Version
                       0.1 addition of notes
                        0.2 Checked, Notes & corrections added.
                                      Sharp crested Rectangular Weir
                                   Sharp crested weir for flow measurement



                Kindsvater-Carter Formula                      Effective width
                                                                   b/B          kb
                    Dimensions and head                             0           2.4       0.2        2.4
           Water Level        (mAOD)     1.100                     0.2          2.4       0.4        2.7
           Invert level       (mAOD)     0.000                     0.4          2.7       0.6        3.6
           Weir crest level   (mAOD)     1.000                     0.6          3.6       0.7        4.1
           Crest length b       (m)      1.000                     0.7          4.1       0.8        4.2
           Channel Width B      (m)      2.000                     0.8          4.2       0.9        3.3
           head h               (m)      0.100                     0.9          3.3        1        -0.9
                         b/B             0.500                      1          -0.9
           weir height p        (m)      1.000
               Effective head and crest width                  Coefficient of Discharge
           effective head he    (m)      0.099                    b/B           a
           effective width be   (m)      1.003                      0        0.587        0.2         0.589
           kh                   (m)       0.001                    0.2       0.589        0.4         0.591
           kb                 (m)      0.0032                      0.4       0.591        0.5         0.592
                 Discharge Coefficient Ce                          0.5       0.592        0.6         0.593
                         a             0.5920                      0.6       0.593        0.7         0.594
                         a'            0.0100                      0.7       0.594        0.8         0.596
                        Ce             0.5930                      0.8       0.596        0.9         0.598
                        Discharge                                  0.9       0.598        1.0         0.602
                 Discharge Q           0.0547                       1        0.602

           BS3680:Part 4A (9.6.1.3) Checks                        b/B           a'
           max h/p             2.5         ok                      0        -0.0023       0.2       -0.0018
           Min h (m)          0.030        ok                     0.2       -0.0018       0.4        0.0058
           Min b              0.150        ok                     0.4        0.0058       0.5           0.01
           Min p              0.100        ok                     0.5          0.01       0.6         0.018
                                                                  0.6         0.018       0.7           0.03
                                                                  0.7          0.03       0.8         0.045
                                                                  0.8         0.045       0.9         0.064
                                                                  0.9         0.064       1.0         0.075
                                                                   1          0.075
Notes
     1     Input data to cells with blue type
     2     Calcluation cells in SI units.
     3     This model should not be used without reference to BS 3680:4A
     4     BS 3680:4A also describes the methodology for calculating the flow over V notch weirs.
File

Reference
BS 3680 : Part 4A : 1981 Measurement of liquid flow in open channels. - Method using thin plate weirs.
Version
   0.1     addition of notes
                                                                                                                                   Broad Crested Rectangular Weir


                 Broad Crested Rectangular Weir
                           Model 3.2

                                 Freefall     0.500             Lookup table for C                                                                                                    C for the following values of h1/L
                                                                                                    h1/p          0.1        0.2        0.3        0.4       0.5        0.6     0.7     0.8         0.9       1.0        1.1     1.2     1.3     1.4     1.5     1.6     1.7     1.8
                   Rectangular sharp crested weir                                                   0.1         0.850      0.850      0.850      0.861     0.870      0.885   0.893   0.925      0.948      0.971      0.993   1.016   1.039   1.062   1.085   1.106   1.130   1.148
                                    3
                Discharge         (m /s)    0.200                        L    0.5                   0.2         0.855      0.855      0.855      0.864     0.874      0.888   0.907   0.930      0.954      0.977      1.001   1.026   1.050   1.074   1.096   1.120   1.142   1.159
                d/s water level (mAOD)      0.000                        p    0.4                   0.3         0.864      0.864      0.864      0.868     0.879      0.894   0.913   0.936      0.961      0.986      1.011   1.037   1.061   1.085   1.110   1.132   1.152   1.169
                Weir crest level (mAOD)     0.500                    C est   0.916                  0.4         0.873      0.873      0.873      0.874     0.885      0.901   0.920   0.945      0.969      0.995      1.021   1.047   1.072   1.097   1.122   1.144   1.163   1.180
                Width b            (m)      2.000                       h1   0.089                  0.5         0.882      0.882      0.882      0.883     0.894      0.909   0.929   0.954      0.978      1.005      1.032   1.057   1.083   1.109   1.133   1.154   1.173   1.188
                                                                      h1/p    0.2                   0.6         0.892      0.892      0.892      0.894     0.904      0.920   0.941   0.964     0.990      1.016      1.043    1.067   1.094   1.120   1.143   1.164   1.182   1.196
                Discharge Coefficient C       0.855                   h1/L    0.2                   0.7         0.901      0.901      0.901      0.906     0.916      0.932   0.952   0.975     1.000      1.026      1.052    1.077   1.104   1.129   1.152   1.171   1.188   1.203
                Head over weir     (m)        0.093             C lookup       0.855                0.8         0.911      0.911      0.912      0.916     0.926      0.942   0.962   0.985     1.010      1.036      1.062    1.086   1.112   1.136   1.158   1.176   1.194   1.209
                Upstream head (mAOD)          0.593             C error       -0.061                0.9         0.921      0.921      0.922      0.926     0.936      0.952   0.972   0.996     1.021      1.046      1.072    1.096   1.120   1.143   1.163   1.181   1.199   1.214
                                                                                                    1.0         0.929      0.929      0.931      0.936     0.946      0.962   0.982   1.006     1.031      1.056      1.081    1.106   1.128   1.150   1.169   1.187   1.204   1.220
                Assumptions                                                                         1.1         0.935      0.937      0.940      0.946     0.956      0.972   0.993   1.017     1.042      1.066      1.092    1.115   1.138   1.159   1.177   1.195   1.212   1.228
                Approach velocity neglected                                                         1.2         0.941      0.944      0.949      0.956     0.966      0.982   1.004   1.028     1.053      7.077      1.103    1.126   1.148   1.168   1.186   1.204   1.222   1.237
                Suppressed rectangular weir                                                         1.3         0.946      0.951      0.957      0.966     0.977      0.993   1.016   1.040     1.063      1.089      1.114    1.136   1.158   1.178   1.196   1.214   1.232   1.250
                         C = 0.855                                                                  1.4         0.953      0.959      0.967      0.975     0.986      1.005   1.028   1.050     1.075      1.101      1.124    1.147   1.168   1.187   1.206   1.224   1.244   1.266
                                                                                                    1.5         0.961      0.968      0.975      0.984     0.997      1.018   1.040   1.061     1.086      1.111      1.134    1.156   1.176   1.196   1.215   1.235   1.258   1.277
                                                                                                    1.6         0.972      0.978      0.985      0.994     1.010      1.030   1.050   1.073     1.096      1.119      1.142    1.164   1.184   1.204   1.224   1.245   1.268   1.289



Notes
 1 Input data to cells with blue type
 2 Calcluation cells in SI units.
 3 The use of the automatic lookup table is optional - the value of the discharge coefficient may be inputted manually if preferred
 4 The weir calculation is according to BS3680 part 4E
 5 The weir is supressed - the crest width is the same as the upstream channel.
 6 BS3680 does not define the performance under submerged conditions, however it does define the limits to which the free flow calculations are applicable - See Annex B.
 7 A correction for submerged (drowned) flow may be made according to the reference for drowning of sharp crested weirs.
 8 The bright green cell marked freefall refers to the freeboard between the crest of the weir and the downstream water level.
     Where this number is negative the weir is drowned.
 9 Bos M.G. Provides a more detailed discussion of varoius forms of broad crested weir.
 10 The shaded areas of the graph are not recommended for measurement purposes.
 11 The bright green cell marked freefall refers to the freeboard between the crest of the weir and the downstream water level.

File


Reference
BS 3680 Measurement of liquid flow in open channels Part 4 E Rectangular Broad Crested Weirs
See also
Bos M.G. Discharge Measurement Structures pp28
Version
 0.1 addition of notes
                                                   V Notch Weir


                                                                                              Freefall   -0.100

                 V Notch Weir                                                     V Notch Weir
            3.3 Free Discharging V Notch                                   3.3d V Notch subject to drowning

       Discharge         (m3/s)       0.200                           Discharge              (m3/s)       0.200
       Weir crest level (mAOD)        0.000                           Weir crest level      (mAOD)        1.000
       u/s head         (mAOD)        0.462                           d/s water level       (mAOD)        1.100
                                                                      Upstream water level (mAOD)         1.463
       Angle of V root degrees         90                             Extent of drowning h2   (m)         0.100
       Discharge Coefficient Cd       0.585                           Angle of V root        degrees       90
       Upstream head above crest      0.462                           Discharge Coefficient Cd            0.585
                                                                      Upstream head above crest           0.463
                                                                      Qf                       (m3/s)     0.202
                                                                      Qs                       (m3/s)     0.200
                                                                      Error in Q                          0.000



Notes
 1 Input data to cells with blue type
 2 Calcluation cells in SI units.
 3 Use 0.585 as default weir discharge coefficient where The root angle is 90 degrees (see reference below)
    Model 3.3 and 3.3d differ only in the consideration of the drowning of the weir
 4 The bright green cell marked freefall refers to the freeboard between the crest of the weir and the downstream water level.
    Where this number is negative the weir is drowned.
 5 Qf is the discharge assuming no drowning
 6 Qs is the corrected discharge to account for the drowning

File

Reference
Henderson Open Channel Flow p178
Featherstone R.E. & Nalluri C. Civil Engineering Hydraulics pp 70 (drowning)
Version
0.1 addition of notes
                                                                                                                                               Rectangular Flumes




                         Flume                                                           Flume                                                                                         Flume
                  Model 3.4.1 (simplified)                                      Model 3.4.2 (simplified)                                                             Model 3.4.3 (including drowned condition)                                    Flume
        Level invert                                                            Inverts may be unequal                                                                        Inverts may be unequal                                             Model 3.4.4
                                                                          y (u/s) / y(d/s)                                                                                 y (u/s) / y(d/s)
        Drowning not considered                                                                    1.448                                                                  (assuming free     1.158                                    For Flow Measurement BS3680
                                                                       (assuming free flow)
                                                                                                                                                                                      flow)
                                                                                                                                                                                                                           y (u/s) / y(d/s) (assuming          3.228
                                                                                    Condition OK                                                                      For Measurement: Invalid                                      free flow)
                          Flume                                                          Flume                                                                          For Calculation: Free Flow                                           Condition OK                                                Channel
                                                                                                                                                                                                                                                  Flume                                               mannings formula
          Chainage                       0.600                               Chainage                      1.000                                                                        Flume
                              3                                                                       3
          Discharge        (m /s)        0.100                               Discharge          (m /s)     0.100                                                                                                                     Chainage                           1.000
                                                                                                                                                                                                                                                               3
                                                                                                                                                                          Chainage                        1.000                      Discharge            (m /s)        0.200
        Invert        (mAOD)             0.000                       d/s Invert                (mAOD)      0.000                                                          Discharge          (m3/s)       0.230
        u/s WL        (mAOD)             0.257                       d/s WL                    (mAOD)      0.500                                                                                                           d/s Invert                    (mAOD)         0.000
        u/s TEL       (mAOD)             0.278                       d/s TEL                   (mAOD)      0.508                                                     d/s Invert            (mAOD)         0.000            d/s WL                        (mAOD)         0.500
                     Throat                                          u/s Invert                (mAOD)      0.200                                                     d/s WL                (mAOD)         0.500            d/s TEL                       (mAOD)         0.508
        Width b          (m)             0.400                       u/s WL                    (mAOD)      0.635                                                     d/s TEL               (mAOD)         0.508            u/s Invert                    (mAOD)         0.200
                    Upstream                                         u/s TEL                   (mAOD)      0.837                                                     u/s Invert            (mAOD)         0.000            u/s WL                        (mAOD)         1.169
        Width B          (m)             0.600                       Hump level                (mAOD)      0.300                                                     u/s WL                (mAOD)         0.579            u/s TEL                       (mAOD)         1.171
        Length           (m)             1.000                                            Throat                                                                     u/s TEL               (mAOD)         0.587            Hump level                    (mAOD)         0.300
                           2
        Area            (m )             0.154                       Width b                      (m)      0.300                                                     Hump level            (mAOD)         0.000                                        h est            0.669
        Velocity V1    (m/s)             0.650                                           Upstream                                                                                  IF FREE FLOW                                                    Throat
        Froude Number Fr                 0.409                       Width B                      (m)      1.000                                                     u/s WL                               0.579            Width b                         (m)          0.500
                                                                     Length                       (m)      1.000                                                     u/s TEL                              0.587            Length                          (m)          3.000
                                                                                                    2
        Depth                y1          0.257                       Area                        (m )      0.435                                                                    IF DROWNED                             Roughness                   mm               0.600
                             2
        Kinetic head      v1 /2g         0.022                       Velocity V1                (m/s)      0.230                                                     u/s WL                               0.635            L/k                                          5000
        Total Energy - Flume             0.278                       Froude Number Fr                      0.111                                                     u/s TEL                              0.642                         Coefficients CV and CD
        Total Energy - Channel           0.278                                                                                                                                          Throat                             temp                      degrees              16
                       error             0.000                       Depth                         y1       0.435                                                    Width b                     (m)      0.300            Kinematic viscosity                         1.11E-06
                                                                     Kinetic head               v12/2g     0.003                                                                       Upstream                            Re                                          4.2E+06
                                                                     Total Energy - Flume                  0.637                                                     Width B                   (m)        1.000            Check L/k>4000                                ok
                                                                     Total Energy - Channel                0.637                                                     Length                    (m)        1.000            Check 100000>L/k                              ok
        BS3680:Part 4C Checks                     Ref                                         error        0.000                                                     Area                     (m2)        0.579            Check Re >2 X 105                             ok
        Min y1         0.050                 ok   10.6.1                                                                                                             Velocity V1             (m/s)        0.397            CD                                          0.9446
        Approach Fr          0.5             ok   10.6.2                                                                                                             Froude Number Fr                     0.167            CV                                           1.002
        max b/B              0.7             ok   10.6.2                                                                                                                                                                                      Head Calculation
        Min b                0.1             ok   10.6.3             BS3680:Part 4C Checks                          Ref                                              Depth                       y1       0.579                                                         0.869
        max y/b               3              ok   10.6.3             Min y1                     0.050        ok     10.6.1                                           Kinetic head         v12/2g          0.008                                  Upstream
        max y               2.000            ok   10.6.3             Approach Fr                 0.5         ok     10.6.2                                           Total Energy - Flume                 0.587            Width B                          (m)         1.000
                                                                     max by/B(y+p)               0.7         ok     10.6.2                                           Total Energy - Channel               0.587            Length                           (m)         1.000
                                                                     Min b                         0.1       ok     10.6.3                                                                 error          0.000            Area                              (m2)       0.969
                                                                     max y/b                        3        ok     10.6.3                                                             Drowning                            Velocity V1                      (m/s)       0.206
                                                                     max y                       2.000       ok     10.6.3                                           Exit losses                                           Froude Number Fr                             0.067
                                                                     p refers to the height of the hump                                                              Throat Invert (hump)                 0.000                                        h est            0.869
Notes                                                                                                                                                                Throat depth                         0.446            Depth                               y1       0.969
  1     Input data to cells with blue type                                                                                                                           Kinetic head            v12/2g       0.150            Kinetic head                   v12/2g        0.002
  2     Input data in cells with blue text                                                                                                                           Thraot Velocity             V2    1.71712             Total Energy - Channel                       0.971
  3     Calcluation cells in SI units                                                                                                                                Throat FR               V3        0.82047                                         error            0.000
  4     These calculations should be undertaken with reference to BS 3680 Measurement of liquid flow in open channels Part 4C                                        Downstream Velocity               0.39988             BS3680:Part 4C Checks                                    Ref
  5     The checks shoen herew refer only to the hydraulic conditions at the flume entry. The conditons for the                                                      expansion losses        K            0.3              Min y1                          0.050         ok         10.6.1
                                                                                                                                                                                  2
        approach conditons and the roughness and length of the throat must also be checked.                                                                                (v1-v3) /2g                  0.088              Approach Fr                      0.5          ok         10.6.2
  6     The ratio of depth upstream and downstream as a condition for flow measurement is with respect to the invert of the throat (including hump if present)       Total Energy - Downstream          0.508              max by/B(y+p)                    0.7          ok         10.6.2
  7     The BS checks refer to the undrowned conditions                                                                                                              error E d/s                        0.000              Min b                            0.1          ok         10.6.3
  8     For outline design where the invert is level model 3.4.1 may be used, however an independent check for drowning                                              Total Energy - Throat              0.597              max y/b                           3           ok         10.6.3
        of the flume must be made                                                                                                                                    Entry losses                                          max y                           2.000         ok         10.6.3
 9      For outline design where the invert is may not be level and a model 3.4.1 may be used, acheck on drowning is included in this model.                         Upstream invert                      0.000            p refers to the height of the hump
 10     Model 3.4.3 is similar to model 3.4.2 except that it includes an estimation of the behaviour of the flume under drowned conditions.                          Upstream depth                       0.635
        This estimation is based on the exit and entry losses to a constriction described in the openchannel flow models accompaning this spreadsheet                Kinetic head          v12/2g         0.007            Temperature - Kinematic Viscosity
        It should be used for guidance only, particularly over the transition between modula and drowned flow. The boundary is not clear and requires calibration.   Thraot Velocity             V2    0.36206                            0              1.79E-06               5        0.00000152
 11     Model 3.4.4 is suitable for use in the calibration of flumes provided that all the checks in the model are ok                                                Throat FR               V3        0.14503                           5               1.52E-06              10        0.00000131
        The method is according to section 10.4 of BS3680:4C                                                                                                         entry loss              K            0.3                           10               1.31E-06              15        0.00000114
        The calculation of the Renolds number is using equation 72 - Appendix C.4.2 BS3680:4C                                                                        loss                              0.04508                          15               1.14E-06              20        0.00000101
        If the checks are not ok then the method described in the British Standard should be employed (10.4.2; Appendix C)                                           Total Energy - Throat              0.597                           20               1.01E-06              25        0.00000090
 12     The consideration of drowned flow is evaluated on the assumption that the flume expansion is not truncated. See section 10.3.1 of BS 3680:4C                 error - throat energy              0.000                           25              0.0000009              30        0.00000081
 13     The model for open channel flow is included to calculate the kinetic head for the discharge channel                                                          Total Energy - Upstream            0.642                           30                 8.1E-07
        (which is required for calculating the headlosses through a submerged flume)

                                                                                                                                                                     BS3680:Part 4C Checks                        Ref
                                                                                                                                                                     Min y1                   0.050        ok     10.6.1
                                                                                                                                                                     Approach Fr                0.5        ok     10.6.2
                                                                                                                                                                     max by/B(y+p)              0.7        ok     10.6.2
File                                                                                                                                                                 Min b                      0.1        ok     10.6.3
                                                                                                                                                                     max y/b                     3         ok     10.6.3
References                                                                                                                                                           max y                    2.000        ok     10.6.3
      addition of notes
BS 3680 Measurement of liquid flow in open channels Part 4C                                                                                                          p refers to the height of the hump
Version
 0.1
                                                      Sharp Rectangular Orifice

                      Sharp Rectangular Orifice
                                  Model 3.5

                                              3
                Discharge               (m /s)       0.200                                  Sharp Rectangular Orifice
                Invert                 (mAOD)        7.000                                        Model 3.5 (simplified)
                d/s water level        (mAOD)        0.500
                                                                                                            3
                u/s water level        (mAOD)        1.931                      Discharge                (m /s)            0.200
                u/s Total Energy Level (mAOD)        1.933                      Invert                  (mAOD)             0.000
                                                                                d/s water level         (mAOD)             0.500
                                 Downstream                                     u/s water level         (mAOD)             1.935
                d/s depth                 y2         -6.500
                                                                                d/s depth                  y2              0.500
                                   Orifice
                Orifice width            b (m)       0.200                      Orifice width           b (m)              0.200
                Orifice height           d (m)       0.300                      Orifice height          d (m)              0.300
                Area                    A (m2)       0.060                      Area                    A (m2)             0.060
                Headloss                   (m)       1.431                      Headloss                 (m)               1.435
                Froude Nr                   Fr       1.943                      Froude Nr                 Fr               1.943

                              Calculation of Cd                                 Orofice flush with walls? y/n                n
                Orofice flush with walls? y/n           n                       Suppression ratio                          0.200
                Suppression ratio                     0.20                      Cd                                         0.628
                Cd                                   0.628                      Cv (assumed)                               1.000

                            Calculation of Cv
                Approximate headloss    (m)          1.435
                Approximate upstream depth (m)       1.935
                Cv                                   1.001

                           Upstream Conditions
                US Invert             (mAOD)         0.000
                Width                  B (m)         0.600
                depth                  y1 (m)        1.931
                Velocity                (m/s)         0.17
                Fr                                    0.04
                Kinetic head             (m)         0.002
                Total head        (m above invert)   1.933


Notes
  1 Input data to cells with blue type
  2 Calcluation cells in SI units
  3 The suppression ratio refers to the proportion of the perimeter of the orifice that is flush
      with the upstream channel. It is calculated from data input above.
  4 The coefficient of discharge Cd is dependant on the suppression ratio and reflects the contraction of the flow enterring the orifice.
  5 The coefficient of velocity Cv corrects the headloss according to the approach velocity
  6 The upstream head is the sum of the headloss and the downstream head so this structure is not a "control structure" in the strict sense
      Strictly, control strucutes regulate the head independantly of the downstream conditions
  7 The Froude number is for the flow through the orifice. Contraction downstream of the orifice is neglected so the actual
      froude number may be slightly greater than the value calculated here.
  8 The downstream depth and drowning of the jet from the orifice must be considered in conjunction with the froude number calculated here.
  9 The simplified model neglects the influence of the approach velocity, and does not calculate the
      upstream flow conditions (velocity, energy, Froude number)
 10 The downstream side of the orifice is assumed to be submerged

File

References
Headloss:      Bos M.G. Discharge Measurement Structures p 273
Cd:   Bos M.G. Discharge Measurement Structures p 273
Cv:   Bos M.G. Discharge Measurement Structures p 30
Version
 0.1 addition of notes
                                                           Defined Headloss Model

                Defined headloss model
                            Model 3.6

                         Hydro Brake
                       Model Number
               Chainage              0.000                                                Defined Headloss - Discharge
               Discharge     (m3/s)  0.165                                                         Model 3.6
               DS Invert      (mAOD)     0.000
               DS WL          (mAOD)     0.200                                4.000
               DS TEL         (mAOD)     0.220
                                                                              3.500
               US Invert      (mAOD)     0.000
               US WL          (mAOD)     0.488                                3.000
               US TEL         (mAOD)     0.495



                                                               headloss (m)
                                                                              2.500
                           Downstream                                         2.000
               depth             y2      0.200                                1.500

                            Upstream                                          1.000
               Width b          (m)      0.900                                0.500

               Area           (m2)       0.439                                0.000
               Velocity v    (m/s)       0.376                                    0.000   0.200   0.400    0.600     0.800   1.000     1.200
               Froude Number             1.414                                                        Discharge (m3/s)
               headloss                  0.288
               depth           y1        0.488
               kinetic head    v12/2g    0.007
               TEL               E1      0.495


                              Discharge Headloss    Calculations
                                 m3/s      m
                                0.000    0.000     0.050    0.020
                 Point 1        0.050    0.020     0.100    0.050
                 Point 2        0.100    0.050     0.150    0.160
                 Point 3        0.150    0.160     0.190    0.500
                 Point 4        0.190    0.500     0.210    1.000
                 Point 5        0.210    1.000     0.250    1.300
                 Point 6        0.250    1.300     0.300    1.550
                 Point 7        0.300    1.550     0.450    2.100
                 Point 8        0.450    2.100     0.700    2.800
                 Point 9        0.700    2.800     1.000    3.400
                 Point 10       1.000    3.400
Notes
 1 Input data to cells with blue type
 2 Calcluation cells in SI units.
 3 This model attributes headloss according to the discharge as defined by the table shown
 4 If ten data points are not needed the size of the unused part of the table may be left blank
 5 Features that can be modelled include hydrobrakes and screens and any other equipment for which headloss is defined by the discharge.
 6 Only one value of depth for a given discharge is acceptable therefore hystreysis and other complex performance cannot be modelled - see point 6
 7 The "S" section of the hydrobrake performance curve is not modelled, which is not generally
      a problem for the design or analysis of a treatment works.
 8 Refer to maunfacturers literature for headloss of their equipment

File

Version
 0.1 addition of notes
                                                   Defined Head - Discharge Model
                                                                                                                                             hydpres.ppt

                Defined headloss model
                            Model 3.6

                         Hydro Brake
                       Model Number
                Chainage             0.000                                                   Defined Head - Discharge
               Discharge     (m3/s)  0.165                                                           Model 3.7
               DS Invert      (mAOD)     0.000
               DS WL          (mAOD)     0.200                                4.000
               DS TEL         (mAOD)     0.220
                                                                              3.500
               US Invert      (mAOD)     0.000
               US WL          (mAOD)     0.288                                3.000
               US TEL         (mAOD)     0.308



                                                               headloss (m)
                                                                              2.500
                           Downstream                                         2.000
               depth             y2      0.200
                                                                              1.500
                            Upstream                                          1.000
               Width b          (m)      0.900
                                                                              0.500

               Area           (m2)       0.259                                0.000
               Velocity v    (m/s)       0.638                                    0.000   0.200   0.400    0.600     0.800   1.000   1.200
               Froude Number             1.414                                                        Discharge (m3/s)
               depth           y1        0.288
               kinetic head    v12/2g    0.021
               TEL               E1      0.308

                    Limit of modula flow
               Maximum allowable y2/y1      0.5
               y2/y1                      0.70
               Condition              DROWNED

                              Discharge Headloss    Calculations
                                 m3/s      m
                                0.000    0.000     0.050    0.020
                 Point 1        0.050    0.020     0.100    0.050
                 Point 2        0.100    0.050     0.150    0.160
                 Point 3        0.150    0.160     0.190    0.500
                 Point 4        0.190    0.500     0.210    1.000
                 Point 5        0.210    1.000     0.250    1.300
                 Point 6        0.250    1.300     0.300    1.550
                 Point 7        0.300    1.550     0.450    2.100
                 Point 8        0.450    2.100     0.700    2.800
                 Point 9        0.700    2.800     1.000    3.400
                 Point 10       1.000    3.400
Notes
 1 Input data to cells with blue type
 2 Calcluation cells in SI units.
 3 This model returns the head accoring to the head - discharge performance defined in the table.
 4 If ten data points are not needed the size of the unused part of the table may be left blank
 5 Features that can be modelled include hydrobrakes and screens and any other equipment for which headloss is defined by the discharge.
 6 Only one value of depth for a given discharge is acceptable therefore hystreysis and other complex performance cannot be modelled.
 7 The limits for modula flow define the limits of applicability of the stage discharge performance as defined in this table

File

Version
 0.1 addition of notes