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Article

Optimum hydraulic design of cylindrical weirs

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Pages 86-90 | Received 15 Nov 2018, Accepted 18 Oct 2019, Published online: 24 Oct 2019
 

ABSTRACT

Cylindrical weirs (CW) due to high hydraulic performance, economic, and ease in construction are highly regarded. In this study, the discharge coefficient (Cd) of this structure and its ability to flow energy dissipation were investigated. The results showed that in the range of the relative head (Ratio of the head of flow over the crest to the diameter of the weir: H/D) between 0.15 and 2.0, the Cd varies between 1.0 and 1.4. In the same range of the H/D, such structures can dissipate the flow energy between 80% and 15%. The optimum value of the Cd for economic design purposes is about 1.3, which occurs in the range of the H/D between 0.5 and 0.7.

Notations

µ(kg/m.s)=

Kinetic viscosity

CCW(-)=

Circular crested weirs

Cd(-)=

Discharge coefficient

CW(-)=

Cylindrical weirs

D(m)=

Diameter of cylindrical weir

d(m)=

Depth of flow at upstream of cylindrical weir

EDR=

Energy dissipation ratio

EDR (-)=

Energy dissipation ratio

Fr(-)=

Froude number

Frw(-)=

Weir Froude number

g(m/s2)=

Gravity acceleration

H (m)=

Head of flow over the crest

Hd(m)=

Total head of flow at toe of cylindrical weir

Hu(m)=

Total head of flow at upstream of cylindrical weir

q(m3/s/m)=

Unit Discharge

R(m)=

radius

Re(-)=

Reynolds number

V(m/s)=

Velocity of approached flow

Y(m)=

Depth of flow over the crest at upstream

Y1(m)=

Depth of flow at toe of cylindrical weir or before hydraulic jump

Y2(m)=

Depth of flow after hydraulic jump

yc(m)=

Critical depth of flow

Yp(m)=

Depth of flow in pooled section

ρ (kg/ m3)=

Mass Density of Flow

Disclosure statement

No potential conflict of interest was reported by the authors.

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