The effect of air bubble screen on scouring reduction in a mild 90 degrees bend

Document Type : Research Article

Authors

1 Ph.D. Candidate, Shahid Chamran University of Ahvaz

2 Associate Prof., Shahid Chamran University of Ahvaz,

3 Prof., Shahid Chamran University of Ahvaz

4 Professor, School of Water Science Engineering, Shahid Chamran University of Ahvaz, Ahvaz

5 Ecole polytechnique fédérale de Lausanne (EPFL), switzerland.

Abstract

An air-bubble screen is an innovative technique for riverbank protection along the bends which improve the navigation conditions in the alluvial rivers. In this research, the effects of this structure on a 90° mild and long bend on the bed morphology and flow pattern have been investigated. To this end, the experiments were carried out with three angles 0, 45, 90 degree and four Froude numbers of 0.37, 0.41, 0.45, 0.47 combined with three air discharge. Experiments performed in a mild bend using clearwater showed that the bubble screen was able to redistribute the velocity patterns and bed morphology in the bend. In addition, the results showed that maximum bend scouring is reduced about 47% and
occurs further away from the outer bank and high velocity zone shifted toward the center of the channel. The results showed that the maximum and minimum scour depths in outer bank with 0 and 90 degrees angles respectively. Also, by increase of air discharge ratio the maximum scour depth was decreased.

Keywords


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  • Receive Date: 20 October 2018
  • Revise Date: 22 January 2019
  • Accept Date: 04 February 2019
  • First Publish Date: 21 March 2019