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.
Figure 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:
A 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.
Also 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.
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.