Discharge coefficients for ogee spillways
Discharge over an ogee weir is related to the length of the weir, upstream total head above the weir crest and the discharge coefficient. The discharge coefficient is influenced by several factors; in this study, some parameters that influence discharge coefficients of ogee weirs are investigated. T...
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| Format: | Article |
| Language: | English |
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IWA Publishing
2022-05-01
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| Series: | Water Supply |
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| Online Access: | http://ws.iwaponline.com/content/22/5/5376 |
| _version_ | 1798038640066035712 |
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| author | Farzin Salmasi John Abraham |
| author_facet | Farzin Salmasi John Abraham |
| author_sort | Farzin Salmasi |
| collection | DOAJ |
| description | Discharge over an ogee weir is related to the length of the weir, upstream total head above the weir crest and the discharge coefficient. The discharge coefficient is influenced by several factors; in this study, some parameters that influence discharge coefficients of ogee weirs are investigated. These factors include: the weir upstream slope, apron elevation, and downstream submergence. In this regard, ogee weir physical models were fabricated. These models comprise: an ogee weir with a vertical upstream face, ogee weirs with inclined upstream faces (18, 33, and 45 degrees), ogee weirs with downstream apron thicknesses of 3, 5, 7, and 10 cm in free flow and an ogee weir with a vertical upstream slope under submerged-flow conditions. Results show that for all ogee weirs, the discharge coefficient (C) increases with increasing P/He, and then remains constant (P is the spillway height and He is the head above the weir crest). The value of the discharge coefficient decreases from 2.25 in free-flow conditions to 2.15 with submerged-flow conditions. For a constant head over the ogee weirs (He), the discharge coefficient decreases with increasing downstream apron elevation and submergence. The relative discharge coefficient shows a constant trend initially, with increasing hd/He, then later shows a decreasing tendency (hd is the difference between the downstream head and the ogee spillway crest). The threshold value for submergence ratio (hd/He) is 0.75 in the ogee weir in this study. With increasing submergence ratio from 0.75 to 1, the relative discharge coefficient (Cs/C0) decreases from 0.88 to 0.24. HIGHLIGHTS
Some ogee weir physical models were fabricated.;
Results show that the discharge coefficient increases with increasing P/He, and then remains constant.;
The value of the discharge coefficient decreases from 2.25 in free-flow conditions to 2.15 with submerged-flow conditions.;
The threshold value for submergence ratio is 0.75 in the ogee weir in this study.; |
| first_indexed | 2024-04-11T21:42:43Z |
| format | Article |
| id | doaj.art-193bb0f28cf9436ba5031d4d916cc234 |
| institution | Directory Open Access Journal |
| issn | 1606-9749 1607-0798 |
| language | English |
| last_indexed | 2024-04-11T21:42:43Z |
| publishDate | 2022-05-01 |
| publisher | IWA Publishing |
| record_format | Article |
| series | Water Supply |
| spelling | doaj.art-193bb0f28cf9436ba5031d4d916cc2342022-12-22T04:01:30ZengIWA PublishingWater Supply1606-97491607-07982022-05-012255376539210.2166/ws.2022.129129Discharge coefficients for ogee spillwaysFarzin Salmasi0John Abraham1 Department of Water Engineering, Faculty of Agriculture, University of Tabriz, Tabriz, Iran School of Engineering, University of St. Thomas, 2115 Summit Avenue St. Paul, Minnesota 55105, USA Discharge over an ogee weir is related to the length of the weir, upstream total head above the weir crest and the discharge coefficient. The discharge coefficient is influenced by several factors; in this study, some parameters that influence discharge coefficients of ogee weirs are investigated. These factors include: the weir upstream slope, apron elevation, and downstream submergence. In this regard, ogee weir physical models were fabricated. These models comprise: an ogee weir with a vertical upstream face, ogee weirs with inclined upstream faces (18, 33, and 45 degrees), ogee weirs with downstream apron thicknesses of 3, 5, 7, and 10 cm in free flow and an ogee weir with a vertical upstream slope under submerged-flow conditions. Results show that for all ogee weirs, the discharge coefficient (C) increases with increasing P/He, and then remains constant (P is the spillway height and He is the head above the weir crest). The value of the discharge coefficient decreases from 2.25 in free-flow conditions to 2.15 with submerged-flow conditions. For a constant head over the ogee weirs (He), the discharge coefficient decreases with increasing downstream apron elevation and submergence. The relative discharge coefficient shows a constant trend initially, with increasing hd/He, then later shows a decreasing tendency (hd is the difference between the downstream head and the ogee spillway crest). The threshold value for submergence ratio (hd/He) is 0.75 in the ogee weir in this study. With increasing submergence ratio from 0.75 to 1, the relative discharge coefficient (Cs/C0) decreases from 0.88 to 0.24. HIGHLIGHTS Some ogee weir physical models were fabricated.; Results show that the discharge coefficient increases with increasing P/He, and then remains constant.; The value of the discharge coefficient decreases from 2.25 in free-flow conditions to 2.15 with submerged-flow conditions.; The threshold value for submergence ratio is 0.75 in the ogee weir in this study.;http://ws.iwaponline.com/content/22/5/5376discharge coefficientdownstream apronfree and submerged flowogee weir |
| spellingShingle | Farzin Salmasi John Abraham Discharge coefficients for ogee spillways Water Supply discharge coefficient downstream apron free and submerged flow ogee weir |
| title | Discharge coefficients for ogee spillways |
| title_full | Discharge coefficients for ogee spillways |
| title_fullStr | Discharge coefficients for ogee spillways |
| title_full_unstemmed | Discharge coefficients for ogee spillways |
| title_short | Discharge coefficients for ogee spillways |
| title_sort | discharge coefficients for ogee spillways |
| topic | discharge coefficient downstream apron free and submerged flow ogee weir |
| url | http://ws.iwaponline.com/content/22/5/5376 |
| work_keys_str_mv | AT farzinsalmasi dischargecoefficientsforogeespillways AT johnabraham dischargecoefficientsforogeespillways |