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Experimental study of discharge coefficient for trapezoidal piano key weirs

2016; Elsevier BV; Volume: 50; Linguagem: Inglês

10.1016/j.flowmeasinst.2016.06.005

1873-6998

Ali Mehboudi, Jalal Attari, Seyed Abbas Hosseini,

Irrigation Practices and Water Management

Piano Key Weirs (PKW) have been invented in the last decade to increase discharge capacity of hydraulic structures. Despite extensive studies on this type of weir with a rectangular plan form (RPKW), there are only a few pieces of research addressing trapezoidal piano key weirs (TPKW). In this experimental study, geometrical parameters of TPKW models were varied under different flow conditions and effects on discharge coefficient (Cd) were investigated. The Cd values were found to be mostly influenced by L/W whereas Wi/Wo had the least effect. Results also showed that TPKW has higher discharge efficiency in comparison with RPKW. This was believed to be related to formation of an "interference wedge" over the TPKW. Finally, quantitative values for distinguishing three flow regimes (i.e. nappe, transition and submergence) as well as criteria for design of TPKW are proposed.