Download Visvesvaraya Technological University (VTU) BE ( Bachelor of Engineering) Civil Engineering 17 Scheme 2020 January Previous Question Paper 3rd Sem Fluid Mechanics
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Important Note 1.
Third Semester B.E. Degree Examination, Dec.
/3 a n .2020
Fluid Mechanics
Time: 3 hrs.
Max. Marks: 100
Note: Answer any FIVE full questions, choosing ONE full question from each module.
Module1
1 a. Define the following with symbols and units:
i) Mass density ii) Specific weight iii) Specific gravity. (06 Marks)
b. An oil film of thickness
;
1.5mm is used for lubrication between a square plate of size
0.9m x 0.9m and an inclined plane having an angle of inclination 20
0
. The weight of the
square is 392.4N and it slides down the plane with a uniform velocity of 0.2m/s. Find the
dynamic viscosity of the oil.
(06 Marks)
c. Find the manometer reading 'h for the Fig.Q.1(e)
.
shown below. (08 Marks)
k?sJ!m
L
t5 1044.
(vacuum))
A I R
1?5rn
I
FiR.Q.1(c)
OR
2 a. The surface tension of water in contact with air is given as 0.0725 N/m. The pressure outside
the droplet of water of diameter 0.02mm is atmospheric (10.32 N/cm
2
). Calculate the
pressure within the droplet of water. (04 Marks)
b. A shaft of diameter ] 20mm is rotating inside a journal bearing of diameter 122mm at a
speed of 360rpm. The space between the shaft and the bearing is filled with a lubricating oil
of viscosity 6 poise. Find the power absorbed in oil if the length of bearing is 100mm.
(08 Marks)
c. State and prove the Pascal's law. (08 Marks)
Module2
3 a. Derive an expression for the force exerted on a submerged vertical plane surface by the
static liquid and locatethe position of centre of pressure. (it) Marks)
b. In a twodimensional incompressible flow, the fluid velocity components are given by
u = x ? 4y and v ? 4x. Show that velocity potential exists and determine its form. Find
also the stream function. (10 Marks)
I of 3
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CHIKOD1
2//
ege of vv
0
USN
Important Note 1.
Third Semester B.E. Degree Examination, Dec.
/3 a n .2020
Fluid Mechanics
Time: 3 hrs.
Max. Marks: 100
Note: Answer any FIVE full questions, choosing ONE full question from each module.
Module1
1 a. Define the following with symbols and units:
i) Mass density ii) Specific weight iii) Specific gravity. (06 Marks)
b. An oil film of thickness
;
1.5mm is used for lubrication between a square plate of size
0.9m x 0.9m and an inclined plane having an angle of inclination 20
0
. The weight of the
square is 392.4N and it slides down the plane with a uniform velocity of 0.2m/s. Find the
dynamic viscosity of the oil.
(06 Marks)
c. Find the manometer reading 'h for the Fig.Q.1(e)
.
shown below. (08 Marks)
k?sJ!m
L
t5 1044.
(vacuum))
A I R
1?5rn
I
FiR.Q.1(c)
OR
2 a. The surface tension of water in contact with air is given as 0.0725 N/m. The pressure outside
the droplet of water of diameter 0.02mm is atmospheric (10.32 N/cm
2
). Calculate the
pressure within the droplet of water. (04 Marks)
b. A shaft of diameter ] 20mm is rotating inside a journal bearing of diameter 122mm at a
speed of 360rpm. The space between the shaft and the bearing is filled with a lubricating oil
of viscosity 6 poise. Find the power absorbed in oil if the length of bearing is 100mm.
(08 Marks)
c. State and prove the Pascal's law. (08 Marks)
Module2
3 a. Derive an expression for the force exerted on a submerged vertical plane surface by the
static liquid and locatethe position of centre of pressure. (it) Marks)
b. In a twodimensional incompressible flow, the fluid velocity components are given by
u = x ? 4y and v ? 4x. Show that velocity potential exists and determine its form. Find
also the stream function. (10 Marks)
I of 3
OR
4 a. What are the methods of describing fluid flow? Explain briefly.
(04
b. Define the equation of continuity. Obtain an expression for a threedimensional cont
equation in Cartesian coordinate system. (08 MI
c. Find the magnitude and direction of the resultant water pressure acting on a curved face c
darn which is shaped according to the relation y = x
2
/9 as shown in Fig.Q.4(c). The height
the water retained by the darn is 10m. Consider the width of the darn as unity. (08 Marks)
Fig.Q.4(c)
Module3
5 a. State Bernoulli's theorem. Derive an expression for Bernoulli's theorem from first principle
and state the assumptions made for such a derivation. (10 Marks'
.
b. A horizontal venturimeter with inlet diameter 30cm and throat diameter 15cm is used to

'
measure the flow of oil of specific gravity 0.8. The discharge of oil through venturimeter is
50 litres/s, find the reading of the oilmercury differential manometer. Take Cd 0.98.
(10 Marks)
OR
6 a. A pipe line carrying oil of specific gravity 0.87, changes in diameter from 200mm diameter
at a position A to 500mm diameter at a position B, which is 4 metres at a higher level. If the
pressures A and B are 9.81 N/cm
2
and 5.886 Nicm

respectively and the discharge is 200
litres's determine the loss of head and direction of flow. (10 Marks)
b.
A 45' reducing bend is connected in a pipe line, the diameters at the inlet and outlet of the
bend being 40cm and 20cm respectively. :Find the force exerted by water on the bend if the
intensity of pressure at inlet of bend is 21.58 N/cm
2
. The rate of flow of water is 500 litres/s.
(10 Marks)
Module4
7 a. Define an orifice and a mouthpiece. What are hydraulic coefficients? Explain them.
(06 Marks)
b. The head of water over an orifice of diameter 40rnm is 10m. Find the actual discharge and
actual velocity of the jet at venacontracta. Take Cd = 0.6 and C, = 0.98. (04 Marks)
c. Water flows over a rectangular weir 2m wide at a depth of 200mm and afterwards passes
through a triangular rightangled weir. Take Cd for the rectangular and triangular weir as
0.63 and 0.59 respectively, find the depth over the triangular weir. (10 Marks)
OR
8 a. Derive an expression for the discharge over a triangular notch. (10 Marks)
b. The head of water over an orifice of diameter 100mm is 5m. The water coming out from
orifice is collected in a circular tank of diameter 2m. The rise of water level in circular tank
is 0.45m in 30 seconds. Also the coordinates of a certain point on the jet, measured from
venacontracta are 100cm horizontal and 5.2cm vertical. Find the hydraulic coefficients
c,, c, and cc.
SOC ?elf
(10 Marks)
2 of 3 r
.
(
i
c
k?
CVAkr'?)L'?J,LY
FirstRanker.com  FirstRanker's Choice
LIBRARY
CHIKOD1
2//
ege of vv
0
USN
Important Note 1.
Third Semester B.E. Degree Examination, Dec.
/3 a n .2020
Fluid Mechanics
Time: 3 hrs.
Max. Marks: 100
Note: Answer any FIVE full questions, choosing ONE full question from each module.
Module1
1 a. Define the following with symbols and units:
i) Mass density ii) Specific weight iii) Specific gravity. (06 Marks)
b. An oil film of thickness
;
1.5mm is used for lubrication between a square plate of size
0.9m x 0.9m and an inclined plane having an angle of inclination 20
0
. The weight of the
square is 392.4N and it slides down the plane with a uniform velocity of 0.2m/s. Find the
dynamic viscosity of the oil.
(06 Marks)
c. Find the manometer reading 'h for the Fig.Q.1(e)
.
shown below. (08 Marks)
k?sJ!m
L
t5 1044.
(vacuum))
A I R
1?5rn
I
FiR.Q.1(c)
OR
2 a. The surface tension of water in contact with air is given as 0.0725 N/m. The pressure outside
the droplet of water of diameter 0.02mm is atmospheric (10.32 N/cm
2
). Calculate the
pressure within the droplet of water. (04 Marks)
b. A shaft of diameter ] 20mm is rotating inside a journal bearing of diameter 122mm at a
speed of 360rpm. The space between the shaft and the bearing is filled with a lubricating oil
of viscosity 6 poise. Find the power absorbed in oil if the length of bearing is 100mm.
(08 Marks)
c. State and prove the Pascal's law. (08 Marks)
Module2
3 a. Derive an expression for the force exerted on a submerged vertical plane surface by the
static liquid and locatethe position of centre of pressure. (it) Marks)
b. In a twodimensional incompressible flow, the fluid velocity components are given by
u = x ? 4y and v ? 4x. Show that velocity potential exists and determine its form. Find
also the stream function. (10 Marks)
I of 3
OR
4 a. What are the methods of describing fluid flow? Explain briefly.
(04
b. Define the equation of continuity. Obtain an expression for a threedimensional cont
equation in Cartesian coordinate system. (08 MI
c. Find the magnitude and direction of the resultant water pressure acting on a curved face c
darn which is shaped according to the relation y = x
2
/9 as shown in Fig.Q.4(c). The height
the water retained by the darn is 10m. Consider the width of the darn as unity. (08 Marks)
Fig.Q.4(c)
Module3
5 a. State Bernoulli's theorem. Derive an expression for Bernoulli's theorem from first principle
and state the assumptions made for such a derivation. (10 Marks'
.
b. A horizontal venturimeter with inlet diameter 30cm and throat diameter 15cm is used to

'
measure the flow of oil of specific gravity 0.8. The discharge of oil through venturimeter is
50 litres/s, find the reading of the oilmercury differential manometer. Take Cd 0.98.
(10 Marks)
OR
6 a. A pipe line carrying oil of specific gravity 0.87, changes in diameter from 200mm diameter
at a position A to 500mm diameter at a position B, which is 4 metres at a higher level. If the
pressures A and B are 9.81 N/cm
2
and 5.886 Nicm

respectively and the discharge is 200
litres's determine the loss of head and direction of flow. (10 Marks)
b.
A 45' reducing bend is connected in a pipe line, the diameters at the inlet and outlet of the
bend being 40cm and 20cm respectively. :Find the force exerted by water on the bend if the
intensity of pressure at inlet of bend is 21.58 N/cm
2
. The rate of flow of water is 500 litres/s.
(10 Marks)
Module4
7 a. Define an orifice and a mouthpiece. What are hydraulic coefficients? Explain them.
(06 Marks)
b. The head of water over an orifice of diameter 40rnm is 10m. Find the actual discharge and
actual velocity of the jet at venacontracta. Take Cd = 0.6 and C, = 0.98. (04 Marks)
c. Water flows over a rectangular weir 2m wide at a depth of 200mm and afterwards passes
through a triangular rightangled weir. Take Cd for the rectangular and triangular weir as
0.63 and 0.59 respectively, find the depth over the triangular weir. (10 Marks)
OR
8 a. Derive an expression for the discharge over a triangular notch. (10 Marks)
b. The head of water over an orifice of diameter 100mm is 5m. The water coming out from
orifice is collected in a circular tank of diameter 2m. The rise of water level in circular tank
is 0.45m in 30 seconds. Also the coordinates of a certain point on the jet, measured from
venacontracta are 100cm horizontal and 5.2cm vertical. Find the hydraulic coefficients
c,, c, and cc.
SOC ?elf
(10 Marks)
2 of 3 r
.
(
i
c
k?
CVAkr'?)L'?J,LY
17CV33
Module5
9 a. Derive DarcyWeisbach equation for head loss due to friction in a pipe.
(10 Marks)
b. The rate of flow of water through a horizontal pipe is 0.25 m
3
/s. The diameter of the pipe
which is 200mm is suddenly enlarged to 400mm. The intensity pressure in smaller pipe is
11.772 N/em
2
. Determine:
i) Loss of head due to sudden enlargement
ii) Pressure intensity in large pipe
iii) Power lost due to enlargement. (10 Marks)
OR
10 a. A pipe line of 0.6m diameter is 1.5km long. To increase the discharge, another line of the
same diameter is introduced parallel to the first in the second .half of the length. Neglecting
minor losses, find the increase in discharge if 4f= 0.04. The head at inlet is 300mm.
(10 Marks)
b. Explain the phenomenon of water hammer. Obtain an expression for the rise of pressure
when the flowing water in a pipe is brought to rest by sudden closure of valve and pipe is
elastic. (10 Marks)
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This post was last modified on 02 March 2020