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Design of Coanda Intakes for Optimum Sediment Release Efficiencies

  • Hydraulic Engineering
  • Published:
KSCE Journal of Civil Engineering Aims and scope

Abstract

When the water has to be diverted from a turbid source having a great amount of suspended materials in it, bottom intake structures such as Coanda and Tyrolean types are preferred. To perform this task, diverted water is captured by a transversal rack, and a gallery located in the control crest is utilized. This study was motivated by a search for the best design where the quality of the diverted water can be increased by screening out most of the sediments in the flow. Current work focuses on the water capture and sediment release efficiencies of both Tyrolean and Coanda type intakes through experimental work. It complements and extends existing experimental studies by considering sediment-laden flow. We used a novel sediment feeding system designed specifically for this study in the experiments. Study results pointed out that when sediment release efficiency is considered, all types of Coanda intakes having different design parameters performed better as compared to Tyrolean intakes. Water capture and sediment release efficiencies are related to parameters used in the experiments including Coanda type, rack angle, void ratio, sediment amount, and flow rate based on the statistical analyses of these parameters. An optimum design is proposed with the maximum sediment release efficiency to prevent clogging during the operation of the intakes.

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Abbreviations

a :

Distance between centerline of the two consecutive bars

A, B, C, D, E, F, G:

Coefficients of regression analysis

C c :

Coefficient of curvature

C q :

Discharge coefficient

C w :

The weir coefficient (= 0,635)

d 10, d 30, d 50, d 60 :

Percent of the particles

e :

Gap distance between two consecutive bars

Fr :

Froude number

Fr e :

Froude number based on bar opening

Fr R :

Froude number based on curvature radius

g :

Gravity

h 0 :

Height of water measured in vertical direction

L :

Screen length

m :

Void ratio

Q d i verted :

Diverted discharge

Q in :

Approaching flow discharge

R :

Curvature radius

Si :

Sediment amount in diverted flow

SRE :

Sediment release efficiency

St :

Sediment amount fed into the system

V :

Velocity of incoming flow at the beginning of the screen

W :

Channel width

WCE :

Water capture efficiency

X :

Sagging distance

X1, X2, X3, X4, X5, X6 :

Representative independent variables

Y :

Any dependent parameter

a :

Wire tilt angle

θ :

Screen slope

ρ :

Density of water

ρ s :

Density of sediment

υ :

Kinematic viscosity

σ :

Surface tension

σ D :

Uniformity coefficient

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Acknowledgments

Funding for this study is provided by the Izmir Institute of Technology (IYTE-201). We would like to thank Ozan Sertkaya and Vedat Karasel for their valuable help during the experiments.

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Authors and Affiliations

  1. Dept. of Civil Engineering, Izmir Institute of Technology, Izmir, 35430, Turkey

    Oğuz Hazar & Sebnem Elçi

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  1. Oğuz Hazar
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  2. Sebnem Elçi
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Correspondence to Sebnem Elçi.

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Hazar, O., Elçi, S. Design of Coanda Intakes for Optimum Sediment Release Efficiencies. KSCE J Civ Eng 25, 492–502 (2021). https://doi.org/10.1007/s12205-020-0760-4

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  • DOI: https://doi.org/10.1007/s12205-020-0760-4

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