New Sharp-Crest Weir with Purpose of Increasing Flow Rate Accurate and Decreasing Sediment in Irrigation Channels

Document Type : Original Article

Authors

1 PhD Student, Water Science and Engineering Department. Ferdowsi University of Mashhad.Mashhad Iran

2 Associate Professor, Water Science and Engineering Department. Ferdowsi University of Mashhad.Mashhad, Iran

3 Associate Professor, University of lakehead ,Canada

Abstract

Rectangular weirs are used in irrigation system to measuring flow rate. One of the most important difficult in these weirs is sediment. Gathered sediment at the upstream weirs usually can change the hydraulic structures flow behind the weirs at the upstream. It can be caused to decreasing discharge coefficient and make sharp weir to board weirs. Recently some alternative proposed to solve this defect. Some solution focused to increasing turbulence intensity that it can cause to rising sediment transport at the upstream weirs. This study for obtaining this purpose, introduce new sharp-cosine weirs. In this research velocity components were calculated by using ADV device in grid plane (2cm*4cm). Turbulence intensity counted as Wilcox (1993) equation at the upstream plane weirs. Values turbulence intensity compared with rectangular weir. Result show by using this weir type sediment transport increased 47 percent versus rectangular weir. Also, the turbulence intensity in cosine weir with w/b=0.1 has maximum value. By embanking sediment at the upstream weirs invested effect of turbulence intensity on sediment transport, too. Finally, maximum depth of score hole occurred in cosine weir with w/b=0.1 and this matter indicated that places occurred maximum turbulence intensity predicted these occurred maximum depth of score hole. It emphasizes turbulence intensity has significant relative with sediment transport in sharp weirs.

Keywords

References

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Iranian Journal of Irrigation & Drainage
Volume 12, Issue 5 - Serial Number 71
January and February 2019
Pages 1016-1028

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