University Of Pune Question Paper
S.E. (Mechanical) (Semester – I) Examination, 2011
FLUID MECHANICS
(2003 Course)
Time : 3 Hours Max. Marks : 100
Instructions : 1) Answer three questions from Section I and three
questions from Section II.
2) Answers to the two Sections should be written in
separate books.
3) Neat diagrams must be drawn wherever necessary.
4) Black figures to the right indicate full marks.
5) All questions carry equal marks.
6) Use of logarithmic tables, slide rule, Mollier charts,
electronic pocket calculator and steam tables is
allowed.
7) Assume suitable data, if necessary.
SECTION – I
1. a) Explain the following terms : 8
i) Compressibility
ii) Surface tension
iii) Viscosity
iv) Capillarity
b) A 50 mm diameter and 10 cm long cylindrical body slides vertically down in a
52 mm diameter cylindrical tube. The space between the cylindrical body and
tube wall is filled with oil of dynamic viscosity 1.9 N-S/m2
. Determine its
velocity of fall if its weight is 16 N. 6
c) What is fluid ? What is the difference between real and ideal fluids ? 2
OR
2. a) A capillary tube of diameter 1.5 mm is dipped in i) water ii) mercury. Find the
capillary rise for each case. Surface tension for water and mercury may be
taken as 0.075 N/m and 0.52 N/m respectively. The contact angle may be
taken as 0° and 130° for the two cases respectively. 8
b) Derive continuity equation. 4
c) Explain the concept of ‘Stream tube’ with sketch. 4
3. a) Explain :
i) Center of pressure
ii) Total pressure. 4
b) Explain in brief different pressure measuring devices. 8
c) State and prove Hydrostatic law. 4
OR
4. a) Explain with neat sketch the working of micro manometer. 4
b) State and explain Pascal’s law. 4
c) Explain with neat sketch the method of determining metacentric height of
floating body. 8
5. a) Explain briefly the following heads;
i) Potential head
ii) Velocity head
iii) Datum head. 4
b) In a vertical pipe conveying oil of sp.gr.0.8, two pressure gauges have been
installed at A and B, where diameters are 16 cm and 8 cm respectively. A is 2 m
above B. The pressure gauge readings have shown that pressure at B is
greater than at A by 0.981 N/cm2
. Neglecting all losses calculate the flow rate. 6
c) A 300 mm × 150 mm venturimeter is provided in a vertical pipeline carrying
oil of specific gravity 0.9, flow being upward. The difference in elevation of
the throat section and entrance section of the venturimeter is 300 mm. The
differential U-tube mercury manometer shows a gauge deflection of 250 mm.
Calculate :
i) The discharge of oil, and
ii) The pressure difference between the entrance section and the throat section.
Take Cd = 0.98 and specific gravity of mercury as 13.6. 8
OR
6. a) Compare Venturimeter and Orifice meter. 6
b) A sub-marine fitted with a pitot tube moves horizontally in sea. Its axis is 12 m
below the surface of water. The Pitot tube fixed in front of the sub-marine and
along its axis connected to the two limbs of a U-tube containing mercury, the
reading of which is found to be 200 mm. Find the speed of the sub-marine.
Take the specific-gravity of sea water = 1.025 times fresh water. 8
c) List of forces acting on fluid mass. Explain the significance of each term. 4
SECTION – II
7. a) Derive Hagen-Poiseuille equation for laminar flow in the circular pipes. 10
b) What are repeating variables ? What points are important while selecting repeating
variables ? 6
OR
8. a) A masonry wall of a water tank is 0.9 m thick. At the bottom a crack of
thickness 0.3 mm and 600 mm wide has developed and the crack extends to
the entire thickness of the wall. If the tank contains 4 m of water above the
crack and the other end of the crack is at atmosphere pressure, estimate the
leakage volume per day from the crack. (Kinematics viscosity of water = 0.01
stokes). 8
b) State and explain Buckingham’s π-theorem. 4
c) Explain dimensional homogeneity with an example. 4
9. a) Derive an expression for the power transmission through the pipes. Find also
the condition for maximum transmission of power. 6
b) A siphon of dia. 200 mm connects two reservoirs having a difference of
elevation of 20 m. The total length of siphon is 800 m and the summit is 5 m
above the water level in the upper reservoir. If separation takes place at 2.8 m
of water absolute. Find maximum length of siphon from upper reservoir to
summit. Take friction factor = 0.016, P atm. = 10.3 m of water. 6
c) What is Siphon ? And what are its applications ? 4
OR
10. a) A piping system consists of three pipes arranged in series; the lengths of the
pipes are 1200 m, 750 m and 600 m and diameters 750 mm, 600 mm and
450 mm respectively.
i) Transform the system to an equivalent 450 mm diameter pipe, and
ii) Determine an equivalent diameter for the pipe, 2550 m long. 6
b) Derive Darcy weisbach equation. 6
c) Explain major and minor losses occurred in pipe. 4
11. a) Distinguish clearly between hydrodynamically smooth and rough boundaries. 6
b) State the practical importance of the following boundary layer thickness :
i) Displacement thickness
ii) Momentum thickness
iii) Energy thickness. 6
c) An aeroplane weighing 39.24 kN is flying in a horizontal direction at 360 km/h.
The plane spans 15 m and has wing surface area of 35 m2
. CD = 0.03, air
density = 1.22 kg/m3
.
Determine :
i) Coefficient of lift
ii) Power required to drive plane
iii) Theoretical value of boundary layer circulation. 6
OR
12. a) What are form drag and friction drag ? Explain with example. 6
b) Calculate the friction drag on a flat plate 15 cm wide and 45 cm long, placed
longitudinally in a stream of oil of specific gravity 0.925 and kinematics 0.9
stokes; with a free stream velocity of 6 m/s. Also find ‘thickness’ of boundary
layer’ and shear stress’ at the trailing edge of the plate. 8
c) Explain ‘laminar sub-layer’ and its significance. 4
———————
S.E. (Mechanical) (Semester – I) Examination, 2011
FLUID MECHANICS
(2003 Course)
Time : 3 Hours Max. Marks : 100
Instructions : 1) Answer three questions from Section I and three
questions from Section II.
2) Answers to the two Sections should be written in
separate books.
3) Neat diagrams must be drawn wherever necessary.
4) Black figures to the right indicate full marks.
5) All questions carry equal marks.
6) Use of logarithmic tables, slide rule, Mollier charts,
electronic pocket calculator and steam tables is
allowed.
7) Assume suitable data, if necessary.
SECTION – I
1. a) Explain the following terms : 8
i) Compressibility
ii) Surface tension
iii) Viscosity
iv) Capillarity
b) A 50 mm diameter and 10 cm long cylindrical body slides vertically down in a
52 mm diameter cylindrical tube. The space between the cylindrical body and
tube wall is filled with oil of dynamic viscosity 1.9 N-S/m2
. Determine its
velocity of fall if its weight is 16 N. 6
c) What is fluid ? What is the difference between real and ideal fluids ? 2
OR
2. a) A capillary tube of diameter 1.5 mm is dipped in i) water ii) mercury. Find the
capillary rise for each case. Surface tension for water and mercury may be
taken as 0.075 N/m and 0.52 N/m respectively. The contact angle may be
taken as 0° and 130° for the two cases respectively. 8
b) Derive continuity equation. 4
c) Explain the concept of ‘Stream tube’ with sketch. 4
3. a) Explain :
i) Center of pressure
ii) Total pressure. 4
b) Explain in brief different pressure measuring devices. 8
c) State and prove Hydrostatic law. 4
OR
4. a) Explain with neat sketch the working of micro manometer. 4
b) State and explain Pascal’s law. 4
c) Explain with neat sketch the method of determining metacentric height of
floating body. 8
5. a) Explain briefly the following heads;
i) Potential head
ii) Velocity head
iii) Datum head. 4
b) In a vertical pipe conveying oil of sp.gr.0.8, two pressure gauges have been
installed at A and B, where diameters are 16 cm and 8 cm respectively. A is 2 m
above B. The pressure gauge readings have shown that pressure at B is
greater than at A by 0.981 N/cm2
. Neglecting all losses calculate the flow rate. 6
c) A 300 mm × 150 mm venturimeter is provided in a vertical pipeline carrying
oil of specific gravity 0.9, flow being upward. The difference in elevation of
the throat section and entrance section of the venturimeter is 300 mm. The
differential U-tube mercury manometer shows a gauge deflection of 250 mm.
Calculate :
i) The discharge of oil, and
ii) The pressure difference between the entrance section and the throat section.
Take Cd = 0.98 and specific gravity of mercury as 13.6. 8
OR
6. a) Compare Venturimeter and Orifice meter. 6
b) A sub-marine fitted with a pitot tube moves horizontally in sea. Its axis is 12 m
below the surface of water. The Pitot tube fixed in front of the sub-marine and
along its axis connected to the two limbs of a U-tube containing mercury, the
reading of which is found to be 200 mm. Find the speed of the sub-marine.
Take the specific-gravity of sea water = 1.025 times fresh water. 8
c) List of forces acting on fluid mass. Explain the significance of each term. 4
SECTION – II
7. a) Derive Hagen-Poiseuille equation for laminar flow in the circular pipes. 10
b) What are repeating variables ? What points are important while selecting repeating
variables ? 6
OR
8. a) A masonry wall of a water tank is 0.9 m thick. At the bottom a crack of
thickness 0.3 mm and 600 mm wide has developed and the crack extends to
the entire thickness of the wall. If the tank contains 4 m of water above the
crack and the other end of the crack is at atmosphere pressure, estimate the
leakage volume per day from the crack. (Kinematics viscosity of water = 0.01
stokes). 8
b) State and explain Buckingham’s π-theorem. 4
c) Explain dimensional homogeneity with an example. 4
9. a) Derive an expression for the power transmission through the pipes. Find also
the condition for maximum transmission of power. 6
b) A siphon of dia. 200 mm connects two reservoirs having a difference of
elevation of 20 m. The total length of siphon is 800 m and the summit is 5 m
above the water level in the upper reservoir. If separation takes place at 2.8 m
of water absolute. Find maximum length of siphon from upper reservoir to
summit. Take friction factor = 0.016, P atm. = 10.3 m of water. 6
c) What is Siphon ? And what are its applications ? 4
OR
10. a) A piping system consists of three pipes arranged in series; the lengths of the
pipes are 1200 m, 750 m and 600 m and diameters 750 mm, 600 mm and
450 mm respectively.
i) Transform the system to an equivalent 450 mm diameter pipe, and
ii) Determine an equivalent diameter for the pipe, 2550 m long. 6
b) Derive Darcy weisbach equation. 6
c) Explain major and minor losses occurred in pipe. 4
11. a) Distinguish clearly between hydrodynamically smooth and rough boundaries. 6
b) State the practical importance of the following boundary layer thickness :
i) Displacement thickness
ii) Momentum thickness
iii) Energy thickness. 6
c) An aeroplane weighing 39.24 kN is flying in a horizontal direction at 360 km/h.
The plane spans 15 m and has wing surface area of 35 m2
. CD = 0.03, air
density = 1.22 kg/m3
.
Determine :
i) Coefficient of lift
ii) Power required to drive plane
iii) Theoretical value of boundary layer circulation. 6
OR
12. a) What are form drag and friction drag ? Explain with example. 6
b) Calculate the friction drag on a flat plate 15 cm wide and 45 cm long, placed
longitudinally in a stream of oil of specific gravity 0.925 and kinematics 0.9
stokes; with a free stream velocity of 6 m/s. Also find ‘thickness’ of boundary
layer’ and shear stress’ at the trailing edge of the plate. 8
c) Explain ‘laminar sub-layer’ and its significance. 4
———————
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