# Discharge over a Vee Notch Weir

```University of Duhok
College of Engineering
Department of Mechanic
Title: Discharge over a Vee Notch Weir
Name: Loran
Experimental date: 2/15/2021
Submit date: 2/29/2021
List of content:
1. Introduction
2. Objective
3. Materials and Apparatus
4. Procedures
5. Calculations and Results
6. Reference
1. Introduction :
A weir is a barrier across the width of a river or stream that alters the
characteristics of the flow and usually results in a change in the height of the water
level. Several types of weirs are designed for application in natural channels and
laboratory flumes. Weirs can be broad-crested, short-crested, or sharp-crested.
Sharp-crested weirs, commonly referred to as notches, are manufactured from
sharp-edged thin plates. The relationship between the flow rate and water depth
above the weir can be derived by applying the Bernoulli’s equation and by making
some assumptions with regard to head loss and pressure distribution of the flow
passing over the weir. A coefficient of discharge needs to be determined
experimentally for each weir to account for errors in estimating the flow rate that is
due to these assumptions.
2. Objective :
The objectives of this experiment are to:
a) determine the characteristics of flow over a rectangular and a triangular weir,
and
b) determine the value of the discharge coefficient for both notches.
3. Materials and Apparatus :
The flow over the weir apparatus includes the following elements that are used in
conjunction with the flow channel in the molded bench top of the hydraulics bench

A combination of a stilling baffle and the inlet nozzle to promote smooth flow
conditions in the channel.

A vernier hook and point gauge, mounted on an instrument carrier, to allow
measurement of the depth of flow above the base of the notch.

The weir notches that are mounted in a carrier at the outlet end of the flow channel.
4. Procedures :
This experiment will be performed by taking the following steps:
 Insert the stilling baffle into the slots in the sides of the channel of the
hydraulic bench
 Insert the rectangular weir and fit it tightly using thump nuts
 Start the pump and open the water supply Adjust the water supply and make
 Take for every height a flow discharge
 Repeat the previous procedure for the vee notch also
5. Calculations and Results :
Crest
Level
(mm)
Gauge
Volume
(Lt)
(mm)
Time
(S)
H
(m)
𝟓
𝑯𝟐
𝑸𝒕𝒉
𝑸𝒂𝒄𝒕
𝟑
𝟑
(𝒎 /𝒔)
Cd
(𝒎 /𝒔)
141
54
25
26.75
0.087
0.661
141
57
25
28.46
0.084
0.66
141
61
25
32.42
0.080
0.676
141
76
25
54.47
0.065
0.67
141
94
15
65.2
0.047
0.75
141
105
5
43.49
0.036
0.756
6. Reference :