Download PTU (Punjab Technical University) B.Tech (Bachelor of Technology) / BE (Bachelor of Engineering) 2021 January CE 3rd Sem 76372 Fluid Mechanics Previous Question Paper
Total No. of Pages : 03
Total No. of Questions : 18
B.Tech. (CE) (2018 Batch) (Sem.?3)
FLUID MECHANICS
Subject Code : BTCE-303-18
M.Code : 76372
Time : 3 Hrs. Max. Marks : 60
INST RUCT IONS T O CANDIDAT ES :
1 .
SECT ION-A is COMPULSORY cons is ting of TEN questions carrying TWO marks
each.
2 .
SECT ION-B c ontains F IVE questions c arrying FIVE marks eac h and s tud ents
have to atte mpt any FOUR q ues tions.
3 .
SECT ION-C contains THREE questions carrying T EN marks e ach and s tudents
have to atte mpt any T WO questio ns.
SECTION-A
Write briefly :
1.
Distinguish between compressible and incompressible fluids.
2.
Distinguish between dynamic viscosity and kinematic viscosity.
3.
Define static pressure and vacuum pressure.
4.
Explain rotational and irrotational flow.
5.
Define Euler number and Mach number.
6.
State Buckingham's Pi theorm.
7.
How does turbulence affects the flow properties?
8.
What are the situations in which hydraulic jump occurs?
9.
What do you mean by most economic channel cross section?
10. What are the limitations of Bernouli's equation?
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SECTION-B
11. In a 50mm long journal-bearing arrangement, the clearance between the two at concentric
condition is 0.1 mm. The shaft is 20mm in diameter and rotates at 3000 rpm. The
dynamic viscosity of the lubricant used is 0.01 Pa s and the velocity variation in the
lubricant is linear. Considering the lubricant to be Newtonian, calculate the frictional
torque the journal has to overcome, and the corresponding power loss.
12. A gas follows the law p = (constant)T and flows steadily in a horizontal pipe of constant
diameter. If the flow is isothermal and ratio of pressure at the two sections under
consideration is p1/p2 = 8/7. Find the ratio V1/V2.
13. An oil having viscosity of 7 poise and specific gravity 0.85 flows through a horizontal
50mm diameter pipe with a pressure drop of 18 kN/m2 per meter length of pipe.
Determine :
a) The flow rate of oil and the centre line velocity
b) The total friction drag over 100 m length of pipe and the power required to maintain
the flow
c) The velocity and shear stress at 8mm from the wall.
14. A plate 0.5m ? 0.2m has been placed longitudinally in a stream of crude oil which flows
with undisturbed velocity of 6m/s. Given that oil has a specific gravity 0.9 and kinematic
viscosity 1 stoke, calculate the boundary layer thickness and shear stress at the middle of
the plate. Also calculate friction drag on one side of the plate.
15. A hydraulic jump occurs in a 0.5m wide rectangular channel at the point where depth of
water flow is 0.15m and the Froude number is 2.5. Make calculations for the specific
energy, critical and sequent depths, loss of head and the energy dissipated.
SECTION-C
16. A hollow wooden cylinder of specific gravity 0.56 has an outer diameter of 60 cm and an
outer diameter of 30 cm. It is required to float in oil of specific gravity 0.85. Calculate the
maximum height of the cylinder so that it shall be stable when floating with its axis
vertical. Also calculate the depth to which it will sink.
17. The angle of a reducing bend is 60? (that is deviation from initial direction to final
direction). Its initial diameter is 30 cm and final diameter is 15 cm and is fitted in a
pipeline, carrying a discharge of 360 lit/sec. The pressure at the commencement of the
bend is 2943 bar. The friction loss in the pipe bend may be assumed as 10% of the kinetic
energy at exit of the bend. Determine force exerted by the reducing bend.
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18. Water from a main canal is siphoned to a branch canal over an embankment by means of
wrought iron pipe of 9 cm diameter. The length of the pipe upto the summit is 25 m and
the total length is 65 m. Water surface elevation in the branch canal is 10m below that the
main canal.
a) How many pipes are needed if the total quantity of water required to be conveyed is
60 lit/sec?
b) What is the maximum permissible height of the summit above the water level in the
main canal so that the water pressure of the summit may not fall below 0.2 bar
absolute, the barometer reading being 10m of water?
Entry loss may be assumed as one-half of the velocity head in the pipe and take friction
factor f = 0.0075 in the Darcy equation, hf = 4flV2/2gd.
NOTE : Disclosure of Identity by writing Mobile No. or Making of passing request on any
page of Answer Sheet will lead to UMC against the Student.
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This post was last modified on 26 June 2021