p. −
2476-4019
Vol.21/No.79
p. 1−22
2476-4019
Vol.21/No.79
ratio increases, the discharge conveyance coefficient of all three sloping weir models increases.]]>
p. 23−38
2476-4019
Vol.21/No.79
p. 39−54
2476-4019
Vol.21/No.79
p. 57−72
2476-4019
Vol.21/No.79
p. 73−92
2476-4019
Vol.21/No.79
and Cd is illustrated in Figure (1) for all the models used in this research. The maximum amount of the coefficient Cd for RPKWs and TPKWs with key angles 4º, 8º, 12º, and 14º were attained, respectively as 0.54, 0.58, 0.56, 0.611, and 0.59. This guarantees that the maximum discharge coefficient belongs to TPKW with sidewall angle 12º. The figure also substantiates that Cd takes less values in RPKWs respective to TPKWs, a fact agreeing with the findings of Safarzadeh and Noroozi (2014). Figure (2) draws the curve of Ht/p < /em> against Cd for three height ratios P/Wu. As observed, for all the ratios, first the Cd value grows and reaches its maximum, and then decreases. The decrease in Cd values occurs also along with an increase in the ratio P/Wu. The differences among the values of Cd in various ratios of P/Wu broaden as the ratio Ht/p < /em> increases. So, there is a reverse relationship between Cd and P/Wu. Conclusion In this research, the discharge coefficient and the total heads of trapezoidal and rectangular piano key weirs were studied and compared. Three cycles, total crest length of 1.65 m, the ratio Wi/Wo=1, and three height ratios 0.75, 0.875, and 1 were adopted for the key piano weirs. The sidewall angles of the key for the trapezoidal piano key weirs were selected as 4º, 8º, 12º, and 14º. The most important results obtained were as follows: - In a certain discharge, the total upstream head of TPKW is less than that of the rectangular counterpart. - The discharge coefficient value in TPKW is greater than in RPKW. - The highest discharge coefficient 0.611 corresponded to the 12 º piano key weir. - The Lampiere's equation (2009) provides an acceptable solution for type A and in particular situations. - An increase in P/Wu leads to a decrease in discharge coefficient value. - The maximum discharge capacity of the 12 º TPKW is 2.35 times that of ogee weir, and it is 2.8 times that of the linear sharp-crested weir. Acknowledgement This article was excerpted from a Ph.D. thesis in Water and Hydraulic Structures, Islamic Azad University, Estahban Branch.]]>
p. 93−110
2476-4019
Vol.21/No.79
p. 111−128
2476-4019
Vol.21/No.79
p. 129−140
2476-4019
Vol.21/No.79