DISCHARGE COEFFICIENT OF BROAD-CRESTED WEIRS AS A FUNCTION OF THE RELATIVE WEIR HEIGHT FOR DIFFERENT WEIR LENGTHS

2020;
: 63-68
1
Lviv Polytechnic National University
2
Lviv Polytechnic National University, Department of Hydraulic and Water Engineering
3
Lviv Polytechnic National University, Department of Hydraulic and Water Engineering
4
Lviv Polytechnic National University, Department of Hydraulic and Sanitary Engineering
5
Lviv Polytechnic National University, Department of Hydraulic and Water Engineering

Broad-crested weirs (BCW) are often used in hydraulic engineering and water management. The most complex factor that affects the discharge capacity of BCW is the discharge coefficient. In Ukrainian engineering practice, the flow rate of BCW is defined as a function of the relative height of the spillway wall, while in the most common European methods – as a function of the relative length of the weir. The experimental dependences of the discharge coefficient of rectangular sharp-edged BCW with vertical inlet and outlet walls with the ratio of the weir length and height d/Р = 2; 4 are obtained. A comparison of the obtained results with the values of the discharge coefficient of the same BCW using the methods of Kumin and Hager indicates that this coefficient depends on both the height of the wall and the length of the weir. The corresponding empirical power law dependences are obtained. At the same values of the relative height of the wall, the discharge coefficient for the weir with the ratio d/Р = 4 is significantly lower comparing the weir with d/Р = 2, that can be explained by the more significant effect of friction resistance for the weir with longer threshold.

Azimi, A.H., Rajaratnam, N., Zhu, D.Z. (2013). Discharge characteristics of weirs of finite crest length with upstream and downstream ramps. Journal of Irrigation and Drainage Engineering, 139(1), 75-83.
https://doi.org/10.1061/(ASCE)IR.1943-4774.0000519

Badr, K., Mowla, D. (2014). Development of rectangular broad-crested weirs for flow characteristics and discharge measurement. KSCE Journal of Civil Engineering, 19(1), 136-141. https://doi.org/10.1007/s12205-012-0433-z

Bolshakov, V.A. (1984) Spravochnyk po gidravlike. Kyiv, Vyshcha shkola, 343 pp. (in Russian).

Нager, W.H., Schwalt, M. (1994). Broad-crested weir. Journal of Irrigation and Drainage Engineering, 120(1), 13-26. https://doi.org/10.1061/(ASCE)0733-9437(1994)120:1(13)

Govinda Rao, N.S., Muralidhar, D. (1963). Discharge characteristics of weirs of finite-crest length. La Houille Blanche, 5, 537-545. https://doi.org/10.1051/lhb/1963036

Guven, A., Hassan, M., Sabir, S. (2013). Experimental investigation on discharge coefficient for a combined broad crested weir-box culvert structure. Journal of Hydrology, 500, 97-103. https://doi.org/10.1016/j.jhydrol.2013.07.021

Jalil, S.A., Ibrahim, S.S., Jafer, R.A. (2014). Surface roughness effects on discharge coefficient of broad crested weir. Research Journal of Applied Sciences, Engineering and Technology, 7(24), 5227-5233.
https://doi.org/10.19026/rjaset.7.918

Konstantinov, Yu.K., Hizha, O.O. (2006). Inzhenerna hidravlika. Kyiv, Slovo, 432 pp. (in Ukrainian).

Kulkarni, K.H., Hinge, G.A. (2020). Experimental study for measuring discharge through compound broad crested weir. Flow Measurement and Instrumentation, 75, 101803.  https://doi.org/10.1016/j.flowmeasinst.2020.101803

Rekomendatsii po gidravlicheskomu raschetu vodoslivov. Ch. I. Priamye vodoslivy. Leningrad, Energia, 1974, 58 pp. (in Russian).

Rohalevych, Yu.P. (2010). Hidravlika. Kyiv. Vyshcha shkola. 431 pp. (in Ukrainian).

Salmasi, F., Poorescandar, S., Dalir, A.H., Zadeh, D.F. (2011). Discharge relations for rectangular broadcrested weirs. Tarim Bilimleri Dergisi, 17(4), 324-336. https://doi.org/10.1501/Tarimbil_0000001184

Sturm, T.W. (2001). Open Channel Hydraulic. McGraw-Hill Series in Water Resources and Environmental Engineering, 500.https://doi.org/10.1115/1.1421122

Zachoval, Z., Knéblová, M., Roušar, L., Rumann, J., Šulc, J. (2014). Discharge coefficient of a rectangular sharp-edged broad-crested weir. Journal of Hydrology and Hydromechanics, 62(2), 145-149. https://doi.org/10.2478/johh-2014-0014

Zhuk, V., Matlai, I., Popadiuk, I., Vovk, L. (2020). Discharge coefficient of broad-crested weirs as function of the relative weir length and height for weirs with large length to head ratios. Theoretical and scientific
https://doi.org/10.23939/jtbp2020.02.063

foundations of engineering: collective monograph. International Science Group. Boston, Primedia eLaunch, 96-101.(in Ukrainian). DOI : 10.46299/isg.2020.MONO.TECH.II