Performance improvement of broad crested weirs

Abstract EN

In order to improve the performance of broad crested weirs, forty weir models were manufactured and tested and two hundred thirty six experiments were conducted in a laboratory horizontal channel of 10m length, 0.3m width and 0.45m depth for a wide range of discharges.

The performance of broad crested weir was improved by introducing an upstream face slope, rounding upstream corner and capping the upstream corner with a semi-cylinder in order to reduce the effect of flow separation.

Analysis of experimental results showed that introducing an upstream slope face to square edge broad crested weir improved the performance and gave higher values of discharge coefficient.

Rounding upstream corner increased the values of discharge coefficient and improved the performance of the weir.

Also, capping the upstream corner with semi-cylinder improved the performance of the weir and gave higher values of discharge coefficient.

Two empirical equations were obtained to estimate the value of discharge coefficient in terms of effective head to crest height ratio, upstream corner radius to crest height ratio and radius of cap to crest height ratio with high correlation coefficients.