Document Type : Research Article
Authors
1
MSc graduated, Department of Water Structures, Faculty of Water and Environmental Engineering, Shahid Chamran University, Ahvaz
2
Assist.Prof. Shahid Chamran University of Ahvaz , Ahvaz . Iran
3
Professor, Department of Water Sciences Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran.
10.30482/jhyd.2023.413734.1671
Abstract
Structures such as weirs and orifices, their main function is to measure the flow rate and regulate the water level. The combination of weir and orifice structure has been noticed in the last decade. When there is a flood, by placing several orifices with a certain number and dimensions in the lower part of this weir, it is possible to pass more discharge. In this laboratory research, the percentage increase in discharge rate and changes in water flow in each of the models designed by changing the number and dimensions of orifices in the sharp-crest triangular weir with multiple orifices have been estimated. In the present research 19 weirs with square orifices were designed in five cases from one to five orifices and in dimensions of two to five centimeters and one weir without an orifice was designed as a control test. The results of this laboratory research showed that for a fixed control level, while the same level remains constant, due to the change in the number of orifices or the dimensions of the orifices, the flow discharge has increased. The results of examining the amount of flow rate changes (difference between the flow discharge resulting from the overflow-orifice test and the flow discharge resulting from the overflow without orifice) have shown that in each test sample, with the increase of each orifice created on average by two liters per second and per one increase of every one centimeter in the size of the orifice adds 2.3 liters per second to the water flow discharge. In the best case, for a combined overflow with a change in the size of the orifice from three to four centimeters in a fixed control level, it has the highest percentage of passing flow and is 57%. On the other hand, in the best case, by increasing the number of orifices from three to four apertures in a fixed control level, this percentage increase has reached approximately 42%, and it shows the superiority of these two combined models compared to other tested models.
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