Experimental Study of Discharge Coefficient and Flow Streamlines in a Trapezoidal Piano Key Side Weir

Document Type : Research Paper


1 hydraulic structure,civil engineering collage,tehran university,Tehran,Iran.

2 Hydraulic Structure, Civil engineering collage, Tehran university, Tehran, Iran.

3 Soil and Water Conservation Research Institute, Agricultural Research, Education and Promotion Organization, Tehran, Iran.


The main application of spillway in rivers and dams reservoirs is control and diversion of flood and protection of their related structures. In this research, a laboratory study was performed to test 16 trapezoid piano key A type weir models with different pillars 10, 15 and 20 cm in a canal with 10 meters length, 0.6 m width and 0.6 m height. The proposed weirs were placed on the main canal wall with two arrangements. The results showed that the maximum overflow rate coefficient was corresponded to weirs with p=15cm in both arranments (1 and 2) and the dimentionless ratio of 0.4 <H/P> 0.2 0.4 and also to weir with dimentionless ratio of 0.5 <H/P and p=20cm. Finally, the trapezoid piano key weir with a p=15cm and a B=50cm identified to pass the most appropriate flow regime.


Main Subjects

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