SULTAN QABOOS UNIVER
SITY
Department of Civil Engineering
B.Eng. Examinations, Fall Semester 2003
FLUID MECHANICS
CIVL 4046
December 23, 2003
9:00

12:00
The following is provided for this examination
Answer booklet
Candidates are permi
tted to bring into the examination room
Calculator (programmable or non

programmable).
Class notes and textbook
Instructions to candidates:
The paper consists of FIVE questions.
Attempt all the questions.
FLUID MECHANICS
CIVL 4046
Time allowed: 3
hours
Attempt all the questions.
1
. A 25

mm diameter shaft is pulled through a cylindrical bearing as shown below.
The lubricant that fills the 0.3

mm gap between the shaft and bearing is an oil having
a kinematic viscosity of 0.
0008 m
2
/s and a specific gravity of 0.91. Determine the
force P required to pull the shaft at a velocity of 3 m/s. Assume the velocity
distribution in the gap is linear.
[15%]
2.
A rectangular sluice door as shown below, is hinged at the top at
A and kept closed
by a weight fixed to the door.
The door is 120

cm wide and 90

cm long and the center of gravity of the complete
door and weight is at G, the combined weight being 9810 N. Find the height of the
water
h
on the inside of
the door which will just cause the door to open.
[25%]
3.
A closed tank of fixed volume is used for the continuous mixing of two liquids
which enter at A and B are discharged completely mixed at C. The diameter of the
inlet pipe at A is 150

mm and the l
iquid flows in at the rate of 0.056 m
3
/s and has a
specific gravity of 0.93. At B the inlet pipe is 100

mm diameter, the flow rate is 0.03
m
3
/s and the liquid has a specific gravity of 0.87. If the diameter of the outlet pipe at
C is 175

mm, what will be t
he mass flow rate, velocity and specific gravity of the
mixture discharged?
[20%]
50 cm
P
shaft
bearing
lubricant
h
G
A
30cm
W
B
60
o
4.
A jet of water from a nozzle is deflected through an angle of 60 degrees from its
original direction by a curved vane, which it enters tangentially (shown
below)
without shock with a mean velocity
v
1
of 30 m/s and leaves with a mean velocity
v
2
of
25m/s.
If the mass flow rate from the nozzle is 0.8 kg/s, calculate the magnitude and
direction of the resultant force on the vane if the vane is stat
ionary.
[20%]
5.
A venturi meter having a throat 100

mm in diameter is fitted in a pipeline 250

mm
in diameter through which oil of specific gravity 0.9 is flowing at the rate of 0.1
m
3
/s.
The inlet and the throat of the meter are connected differentiall
y to a U

tube
manometer containing mercury of specific gravity 13.6 with oil immediately above
this. Starting from Bernoulli’s equation find the coefficient of discharge for the meter
if the difference in mercury levels is 0.63 m.
[20%]
v
1
v
2
60
o
Fixed vane
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