Tag Archives: weir crest

Broad Crested Weir Calculations Spreadsheet

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Where to Find a Broad Crested Weir Calculations Spreadsheet

To obtain a Broad Crested Calculations Spreadsheet, click here to visit our spreadsheet store.  This Excel spreadsheet is intended for calculating the flow rate over the weir for free flow over the weir or for submerged flow.  . You can buy a convenient broad crested weir calculations spreadsheet for a very reasonable price.  It is available in either U.S. units or S.I. units.  Read on for background information about a broad crested weir calculations spreadsheet

Background for a Broad Crested Weir Calculations Spreadsheet

Figure 1, below shows a longitudinal section of a broad crested weir with free flow over the weir.

Broad crested weir calculations spreadsheetFigure 1. Longitudinal Section of a Broad Crested Weir with Free Flow over the Weir

The flow over a broad crested weir is referred to as free flow if the depth of water flowing immediately downstream of the weir is lower than the weir crest (the top of the weir), as shown in Figure 1.  The broad crested weir calculations spreadsheet being described here can calculate the flow rate over the weir for user specified values of the depth of flow upstream of the weir, y1, the length of the weir crest, L, (typically equal to the width of channel in which the broad crested weir is placed), and the value to be used for the weir coefficient, C.  The equation used for this calculations is:

broad crested weir calculations spreadsheetA similar calculation can be made for submerged flow over the broad crested weir, in which the depth of flow immediately downstream of the weir is greater than the height of the weir.  Submerged flow over a broad crested weir is shown in Figure 2 below.

broad crested weir calculations spreadsheetAlso the required upstream head above the weir crest can be calculated for a given flow rate over the weir for either free flow over the weir or submerged flow

Example Broad Crested Weir Calculations Spreadsheet

An example broad crested weir calculations spreadsheet is partially shown in the image below.  .  This Excel spreadsheet can be used to calculate the flow rate over the weir or to calculate the required upstream head over the weir for a given flow rate. These calculations can be made for free flow over the weir or for submerged flow over the broad crested weir.  This Excel spreadsheet, as well as others for open channel flow measurement calculations, is available in either U.S. or S.I. units for a very reasonable price in our spreadsheet store.

broad crested weir calculation spreadsheet screenshot

References:

1. Federal Highway Administration,  Publication No. FHWA-HIF-12-018, Hydraulic Design Series Number 7, Hydraulic Design of Safe Bridges, April 2012.2

2. Bengtson, Harlan H.,  “ Spreadsheet for Broad Crested Weir Calculations,” an online blog article.

Partially Contracted V-Notch Weir Excel Spreadsheets

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Where to Find a Partially Contracted V-Notch Weir Excel Spreadsheet

To obtain a Partially Contracted V-notch weir Excel spreadsheet for , click here to visit our spreadsheet store. Why use online calculators or hand calculations when you can buy a partially contracted V-notch weir spreadsheet for only $11.95.  Read on for information about Excel spreadsheets that can be used as v-notch weir open channel flow calculators for partially contracted flow.

For background on fully contracted v notch weir calculations, see the article, “V-Notch Weir Calculator Excel Spreadsheet.”   That article gives general information about V notch weirs and equations and conditions required for fully contracted v notch weir calculations.

Partially Contracted V Notch Weir Calculations for a 90o Notch Angle

Partially contracted v-notch weir excel spreadsheet diagram

The equation shown below is recommended by the U.S. Dept. of the Interior, Bureau of Reclamation in their Water Measurement Manual (ref #1 below) for calculations with a partially contracted, 90o, v notch, sharp crested weir with free flow conditions and 0.4 ft < H < 2 ft (0.05 m < H < 0.38 m).

In U. S. units:  Q = 4.28H2.48, where Q is discharge in cfs and H is head over the weir in ft.

In S.I. units:  Q = 1.36H2.48, where Q is discharge in  m3/s and H is head over the weir in m.

The conditions for the v notch weir to be fully contracted are:

H/P < 1.2,    H/B < 0.4,    P > 0.33 ft (0.1 m),   B > 2 ft (0.6 m)

The diagram above shows the parameters H, P, θ and B for a v notch weir as used for open channel flow rate measurement in a partially contracted v-notch weir excel spreadsheet.

Screenshot of a Partially Contracted V Notch Weir Excel Spreadsheet

The screenshot below shows a partially contracted v notch weir excel spreadsheet for making 90o, partially contracted v-notch weir calculations in U.S. units.  Based on specified values for H, P, & B (and a value for Ce from a graph on the spreadsheet), the spreadsheet checks on whether the required conditions for partially contracted flow are met and then calculates the flow rate, Q.  This Excel spreadsheet and others for v notch weir calculations are available in either U.S. or S.I. units at a very low cost (only $11.95)  in our spreadsheet store.

partially contracted v-notch weir spreadsheet screenshot

References:

1. U.S. Dept. of the Interior, Bureau of Reclamation, 2001 revised, 1997 third edition, Water Measurement Manual, available for online use or download at: http://www.usbr.gov/pmts/hydraulics_lab/pubs/wmm/index.htm.

2. Bengtson, Harlan H., “Sharp Crested Weirs for Open Channel Flow Measurement,” an Amazon Kindle ebook

3. Bengtson, Harlan H., Open Channel Flow III – Sharp Crested Weirs, an online continuing education course for PDH credit, http://www.online-pdh.com/engcourses/course/view.php?id=87

4. Munson, B. R., Young, D. F., & Okiishi, T. H., Fundamentals of Fluid Mechanics, 4th Ed., New York: John Wiley and Sons, Inc, 2002.

Proportional Sutro Weir Design Calculation Excel Spreadsheet

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Where to get a Proportional Sutro Weir Design Calculation Excel Spreadsheet

For a proportional sutro weir design calculation Excel spreadsheet in either U.S. or S.I. units, click here to visit our spreadsheet store.  Obtain convenient, easy to use spreadsheets for proportional sutro weir design calculations at reasonable prices. Read on for information about the use of a proportional sutro weir design calculation Excel spreadsheet.

Principles of a Proportional Sutro Weir Design Calculation Excel Spreadsheet

For the commonly used rectangular weir or V-notch weir, the flow rate over the weir Diagram for proportional sutro weir design calculation excel spreadsheetincreases as the head over the weir increases, but the flow rate increases at a faster rate than the head over the weir.  For some applications, it is desirable for the flow rate over a weir to be proportional to the head over the weir.  The sutro weir, also known as a proportional weir accomplishes this by having the width of the opening above the weir crest decrease with increasing head over the weir crest as shown in the diagram of a sutro weir at the right.  Equations that can be used for proportional sutro weir design are discussed in the next section.

Equations for Proportional Sutro Weir Design Calculation Excel Spreadsheet

Equations for the base width and base height of a sutro weir are as follows:

base height equation for proportional sutro weir design calculation Excel spreadsheet

base width equation for proportional sutro weir design calculation Excel spreadsheet

  • Wb  =  base width in ft (m for S.I. units)
  • Hb  =  base height in ft (m for S.I. units)
  • Hc  =  max height or curved portion of weir in ft (m for S.I. units)
  • Qmax  =  design maximum flow over the weir in cfs (m3/s for S.I. units)
  • Qmin  =  design minimum flow over the weir in cfs (m3/s for S.I. units)
  • g = acceleration of gravity = 32.17 ft/s/s (9.81 m/s/s for S.I. units)

The equation for the curved portion of a proportional sutro weir is:

Curve Equation for proportional sutro weir design calculation Excel spreadsheet

X and Z are position parameters as shown in the diagram above.  They will have the same units as Wb .

A Screenshot for a Proportional Sutro Weir Design Calculation Excel Spreadsheet

For a proportional sutro weir design calculation Excel spreadsheet with calculations in S.I. or U.S. units, or for other spreadsheets for open channel flow measurement calculations, see: www.engineeringexceltemplates.com

The Excel spreadsheet screenshot below shows part of a spreadsheet for proportional sutro weir design calculations, available  at our spreadsheet store in either U.S. or S.I. units at a very reasonable price.

 Screenshot of Proportional Sutro Weir Design Calculation Excel Spreadsheet

Reference

1, U.S. DOT, Fed Highway Admin, Urban Design Manual, Circular No. 22, 2nd Ed. 2001  (Publ. No. FHWA-NHI-010021-HEC-22)

2. Bengtson, Harlan H., “Proportional Weir Design Equations,” an online blog article