Journal of Hydraulics

Journal of Hydraulics

Discharge-Level laboratory investigation of the flow passing through the composite structure of sharp crested triangular with multiple orifices

Document Type : Research Article

Authors
Seyedeh Negar Sadat Ahmadi 1
mehdi zeinivand 2
Mehdi Ghomeshi 3
1 MSc graduated, Department of Water Structures, Faculty of Water and Environmental Engineering, Shahid Chamran University, Ahvaz
2 Assistant Professor in Hydraulic Structures, College of water science engineering, SHAHID CHAMRAN University of 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.
Keywords
sharp-crested-triangular
Multiple orifices
flow discharge
discharge percentage

Subjects

Altan-Sakarya, A.B. & Kökpınar, M.A. (2013). Computation of discharge for simultaneous flow over weirs and below gates (H-weirs). Flow Measurement and Instrumentation, 29, 32-38.
Ali, M.S., Qadri, A. & Mansoor, T. (2015). Flow characteristics of a triangular sharp crested weir. In: HYDRO 2015 International Conference, Roorkee, India.‏
Al-Suhili, R.H. & Shwana, A.J. (2013). Prediction of the discharge coefficient for a Cipolletti weir with rectangular bottom opening. Journal of Engineering Research and Applications, 4(1), 80-89.
Akhbari, A., Zaji, A.H., Azimi, H. & Vafaeifard, M. (2017). Predicting the discharge coefficient of triangular plan form weirs using radian basis function and M5’methods. Journal of Applied Research in Water and Wastewater, 4(1), 281-289.
Achour, B. & Amara, L. (2022). Triangular Broad Crested Weir Theory and Experiment. Larhyss Journal, ISSN 1112-3680, 49, 37-66.
Alhamid, A., Negm, A.-A. M. & Al-Brahim, A. (1997). Discharge equation for proposed self-cleaning device. Journal of King Saud University-Engineering Sciences, 9(1), 13-23.
Balouchi, B. & Rakhshandehroo, G. (2018). Using physical and soft computing models to evaluate discharge coefficient for combined weir–gate structures under free flow conditions. Iranian Journal of Science and Technology, Transactions of Civil Engineering, 42, 427-438.
Balouchi, B. & Zinivand, M. (2012). Experimental investigation on discharge coefficient for combined structure of weir-gate under flood conditions. Water and Soil Science, 22(2), 152-164.
Chanson, H. (2010). Discussion of “Hydraulics of Broad-Crested Weirs with Varying Side Slopes” by JE Sargison and A. Percy. Journal of Irrigation and Drainage Engineering, 136(7), 508-509.
Ferro, V. (2000). Simultaneous flow over and under a gate. Journal of Irrigation and Drainage Engineering, 126(3), 190-193.
Hoseini, S.H. (2014). Experimental investigation of flow over a triangular broad-crested weir. ISH Journal of Hydraulic Engineering, 20(2), 230-237.
Hayawi, H., Yahia, A. & Hayawi, G. (2008). Free combined flow over a triangular weir and under rectangular gate. Damascus University Journal, 24(1), 9-22.
Negm, A.-A.M., Al-Brahim, A. & Alhamid, A. (2002). Combined-free flow over weirs and below gates. Journal of Hydraulic Research, 40(3), 359-365.
Negm, A. (1995). Characteristics of combined flow over weirs and under gates with unequal contractions. In: Advances in Hydroscience and Engineering, Tsinghua University Press, Beijing, China, 285-292.
Pesaraklo, M. & Emadi, A. (2015). The experimental investigation of combined flow in sharp crested weir and gate in the state of compound weir. The 2nd National Conference on Water, Human and Land. (In Persian)
Piratheepan, M., Winston, N. & Pathirana, K. (2006). Discharge measurements in open channels using compound sharp-crested weirs. Journal of the Institution of Engineers, Sri Lanka, 40(3), 31-38.
Shabani, E., Zahiri, A., Dehghani, A.A. & Meftah Halghi, M. (2018). Experimental investigation of flow discharge coefficient for combined system of compound weirs-orifices. Journal of Water and Soil Conservation, 25(3), 209-224.
Salehi, S. & Azimi, A.H. (2019). Discharge characteristics of weir-orifice and weir-gate structures. Journal of Irrigation and Drainage Engineering, 145(11), 04019025, https://doi.org/ 10.1061/(ASCE)IR.1943-4774.0001421.

  • Receive Date 08 October 2023
  • Revise Date 28 November 2023
  • Accept Date 03 December 2023