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Weir Types and Classifications

The document discusses different types of weirs used in hydraulics. It describes weirs as barriers placed in open channels to measure water discharge. Weirs are classified based on the shape of their crest, the shape of their opening, and the effect of their sides. Common weir types include rectangular, triangular, trapezoidal, suppressed, and contracted weirs. Equations are provided for calculating discharge over various weir shapes using parameters like head, length, and coefficient of discharge.

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Keith Ralph Vacio
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206 views10 pages

Weir Types and Classifications

The document discusses different types of weirs used in hydraulics. It describes weirs as barriers placed in open channels to measure water discharge. Weirs are classified based on the shape of their crest, the shape of their opening, and the effect of their sides. Common weir types include rectangular, triangular, trapezoidal, suppressed, and contracted weirs. Equations are provided for calculating discharge over various weir shapes using parameters like head, length, and coefficient of discharge.

Uploaded by

Keith Ralph Vacio
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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HYDRAULICS

JEJOMAR DUQUE, CE
HYDRAULICS

I. CONSTANT HEAD WEIRS


II. FALLING HEAD WEIRS
II. HYDRAULICS
WEIR
Any control or barrier
placed in an open
channel to permit
measurement of water
discharge.

CLASSIFICATION OF WEIRS
A. BASED ON SHAPE OF THE CREST
B. BASED ON SHAPE OF THE OPENING
C. BASED ON EFFECT OF THE SIDES ON THE
EMERGING NAPPE
II. HYDRAULICS
PROFILE OF A WEIR

≈ 4H
CREST
H `
NAPPE

≈2H APPROACH

PLATE
II. HYDRAULICS
WEIR
A. CLASSIFICATION BASED ON SHAPE OF CREST
1. Sharp-crested weir 2. Broad-crested weir
II. HYDRAULICS
WEIR
A. CLASSIFICATION BASED ON SHAPE OF CREST
3. Ogee-shaped weir
II. HYDRAULICS
WEIR
B. BASED ON SHAPE OF THE OPENING
1. Rectangular weir:
It is a standard shape of weir. The top edge of weir
may be sharp crested or narrow crested.
𝟐
H 𝑸 = 𝑪 𝟐𝒈𝑳𝑯𝟏.𝟓
𝟑

𝑸 = 𝑪𝒘 𝑳𝑯𝟏.𝟓

L Where: 𝑯 = head of the weir


FRANCIS FORMULA 𝑪 = coefficient of discharge
𝑪𝒘 = 𝟏. 𝟖𝟒 𝑪𝒘 = coeff. of discharge
II. HYDRAULICS
WEIR
B. BASED ON SHAPE OF THE OPENING
2. Triangular weir (V-notch weir)
The shape of the weir is actually reverse triangle like
V. so, it is also called V-notch weir.
𝟖 𝜽
θ H 𝑸= 𝑪𝒕𝒂𝒏 𝟐𝒈𝑯𝟐.𝟓
𝟏𝟓 𝟐
Where: 𝑯 = head of the weir
𝑪 = coefficient of discharge
L 90° V-notch weir
𝑸 = 𝟏. 𝟒𝟐𝑯𝟐.𝟓
II. HYDRAULICS
WEIR
B. BASED ON SHAPE OF THE OPENING
3. Trapezoidal weir
Cippoletti weir
θ/2 θ/2
H When: tan 𝛉/2 = 0.25
side slope = 1:4
𝑸 = 𝟏. 𝟖𝟔𝑳𝑯𝟏.𝟓

𝟐 𝟏.𝟓
𝟖 𝜽
𝑸 = 𝑪 𝟐𝒈𝑳𝑯 + 𝑪𝒕𝒂𝒏 𝟐𝒈𝑯𝟐.𝟓
𝟑 𝟏𝟓 𝟐
II. HYDRAULICS
WEIR
C. BASED ON EFFECT OF THE SIDES ON THE
EMERGING NAPPE

L L

SUPPRESSED WEIR CONTRACTED WEIR

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