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# Hydraulics Revision Exercise

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QUESTION 1
HDR370S - Hydraulics Revision Exercise
A 3.6 m high and 1.5 m wide rectangular gate AB is vertical and is hinged at a point 150 mm below the centre of
gravity of the gate. The total depth of water is 6.1 m. What horizontal force F must be applied at the bottom of
the gate for equilibrium?
A
6.1 m
G
150 mm
Hinge
F
B
QUESTION 2
A concrete dam has the cross-sectional profile as shown in the accompanying figure. Calculate the magnitude
and direction of the resultant force exerted by the water per metre width of dam.
QUESTION 3
Use the pipe-design chart (figure 1) for a tar covered steel pipe to determine the pressure drop (kPa) in a 400
m long, 50 mm diameter pipeline if the flow rate is 120 L/min.
QUESTION 4
A pipeline 800 m long of diameter 40 mm conveys water with a viscosity &micro;=1.14 x 10-3 Ns/m2. The flow rate is
0.6 L/s and pipe wall roughness k is 0.08 mm. Calculate the friction head loss using:
a. The Moody diagram (provided -use ff)
b. The Manning formula with n = 0.008
c. Chezy formula with C = 60
QUESTION 5
Water is flowing at a velocity of 2 m/s in a 100 mm diameter pipe of a total length of 100 m.
Calculate the total head loss and the difference in elevation of the two reservoirs using the following information:
• Equivalent length of globe valve: 34 m
• Elbow loss coefficient: 0.8
• Friction factor in the pipe: 0.006
• Pipe entrance loss coefficient: 0.5
• Pipe exit loss coefficient: 1.
QUESTION 6
Water is flowing in a triangular/rectangular channel as shown. For a channel slope of 0.0009 and total depth of
1.5 m at the centre, determine the discharge using the Manning formula. Take the Manning coefficient = 0.013.
0.5 m
0.5 m
[6]
100&deg;
Manning: v =
0.397 2 3 12
D i
n
Darcy – Weisbach: h f =
1
Manning: π£π£ = ππ ππ
2οΏ½ 1οΏ½
3 ππ 2
1.0 m
Re =
ρVD
&micro;
4 fLV 2
fLQ 2
=
2 gD
3.03D 5
Chezy: π£π£ = πΆπΆ √ππππ