Experimental Investigation of using the Piano Key Weirs in the Outlet of the Clarifier Structure

Document Type : Research Paper


1 PhD student, Department of Water Science and Engineering, Shoushtar Branch, Islamic Azad University, Shoushtar, Iran

2 Department of Water Sciences, Water Science and Environmental Research Center, Shoushtar Branch, Islamic Azad University, Shoushtar, Iran

3 Department of Water Sciences, Water Science and Environmental Research Center, Shoushtar Branch, Islamic Azad University, Shoushtar, Iran.


Sustainable development and survival depends on environmental protection, especially water. Water treatment aims to produce safe and healthy water, which is possible in water treatment plants. Therefore the importance of water is understandable, and the importance of building and equipping a water treatment plant is paramount. Many principles have been proven. Moreover, ideas for upgrading treatment plants worldwide have increased treatment plants' capacity and improved water quality.. The proposed methods can not only be applied to optimize existing water treatment plants but can also be used to design New refineries will also be used. One of the critical parts that are considered in clarifiers is the weir part. Increasing the weir width to increase the discharge capacity of the design due to the width limit is one of the problems that designers face. This has led engineers to design weirs with nonlinear geometry. Congress weir and piano keys are two essential types of nonlinear overflows in which the length of the weir crest is increased by the crinkle of this structure in the plan. The use of nonlinear overflows is increasing worldwide, which has led researchers to estimate the discharge coefficient for weir efficiency. Tullis et al. (2020) conducted a study to investigate the effect of engineering specifications on the hydraulic performance of congressional weirs. The results of this study showed the effect of the number of weir cycles on hydraulic performance. As the number of congressional weir cycles increases, the hydraulic performance of the overflow decreases. Kumar et al(2019)., in their research, examined the effect of the ratio of crest length to width (L/W) and overflow height (P) of the piano key. Using soft calculations, the discharge coefficient was considered a function of geometric variables without the dimension of piano key overflow. Therefore, in this research, an attempt was made to evaluate the hydraulic flow in the overflow of refinery clarifier structures with the shape of a piano key at its outlet using a physical model.


Main Subjects

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2- Crookston, B., Anderson, R. & Tullis, B. 2018. Free-flow discharge estimation method for Piano Key weir geometries. Journal of Hydro-Environment Research, 19, 160-167.


3- Hien, T., Son, H. & Khanh, M. 2006. Results of some piano keys weir hydraulic model tests in Vietnam, in proceedings of 22e congrès des grands barrages. CIGB/ICOLD, Barcelona.


4- Kabiri-Samani, A. & Javaheri, A. 2012. Discharge coefficients for free and submerged flow over Piano Key weirs. Journal of Hydraulic research, 50, 114-120.


5- Kumar, B., Kadia, S. & Ahmad, Z. 2019. Evaluation of discharge equations of the Piano Key Weirs. Flow Measurement and Instrumentation, 68, 101577.

6- Laugier, F. 2007. Design and construction of the first Piano Key Weir spillway at Goulours dam. International Journal on Hydropower and Dams, 14, 94.


7- Laugier, F., Lochu, A., Gille, C., Leite Ribeiro, M. & Boillat, J.-L. 2009. Design and construction of a labyrinth PKW spillway at Saint-Marc dam, France. Hydropower & Dams, 16, 100-107.


8- Lemperiere, F. & Ouamane, A. 2003. The Piano Keys weir: a new cost-effective solution for spillways. International Journal on Hydropower & Dams, 10, 144-149.


9- Pirzad, M., Pourmohammadi, M., Ghorbanizadeh Kharazi, H., Solimani Babarsad, M. & Derikvand, E. 2022. Experimental study on flow over arced-plan porous weirs. Water Supply, 22, 2659-2672.


10- Ribeiro, L., Bieri, M., Boillat, J., Schleiss, A., Singhal, G. & Sharma, N. 2012a. Discharge capacity of piano key weirs. Journal of Hydraulic Engineering, 138, 199-203.


11- Ribeiro, M. L., Pfister, M., Schleiss, A. J. & Boillat, J.-L. 2012b. Hydraulic design of A-type piano key weirs. Journal of Hydraulic Research, 50, 400-408.


12- Tullis, B. P., Crookston, B. M., Brislin, J. & Seamons, T. 2020. Geometric Effects on Discharge Relationships for Labyrinth Weirs. Journal of Hydraulic Engineering, 146, 04020066.

Volume 45, Issue 4
February 2023
Pages 145-156
  • Receive Date: 22 January 2022
  • Revise Date: 06 September 2022
  • Accept Date: 10 September 2022
  • Publish Date: 20 February 2023