Experimental study of the effect of jump on the scour downstream of type-C trapezoidal piano key weir

Document Type : Research Article

Authors

1 civil engineering department, Islamic azad university, Isfahan branch

2 Faculty of Civil Engineering, Islamic Azad University of Isfahan (Khorasgan), Isfahan, Iran

3 Faculty of Civil and Environmental Engineering, Tarbiat Modares University, Tehran, Iran

Abstract

Piano key weirs represent an evolved and novel type of labyrinth weirs, offering a higher water flow coefficient when compared to linear weirs. In this research, a type-C trapezoidal piano key weir with a height of 0.2 meters was utilized, incorporating two jumps with radii of 0.15 and 0.21 meters at the weir exit keys. The findings indicated that the presence of a jump contributes to an increase in maximum scour depth. Furthermore, the presence of a jump causes the maximum scouring depth to occur further away from the weir toe. Increasing the radius of the jumps also results in an augmented maximum scour depth. The length of the maximum scour depth, compared to the weir toe, is approximately 12% greater in weirs with a larger jump radius than those with a smaller radius. On average, the maximum length of the scour depth in relation to the weir toe is 29.4% and 19.5% longer in weirs with jump radii of 0.21 and 0.15 meters, respectively, compared to weirs without jumps. Additionally, the presence of a jump diminishes scouring at the weir toe, with toe scour being approximately 42% less pronounced in weirs with a larger jump height compared to weirs without jumps. The average scour index in weirs with jump radii of 0.21 and 0.15 meters is approximately 2.77% and 0.52% lower, respectively, compared to weirs without jumps. Moreover, an increase in jump radius correlates with a decrease in the water permeability coefficient.

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Amirkabir Journal of Civil Engineering

Articles in Press, Accepted Manuscript
Available Online from 03 October 2024

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