Reg. No.
Question Paper Cod e :77070
B.E./B.Tech. DEGREE EXAMINATION, APRIUMAY 20L5.
, : Third Semester
.
Mechanical Engineering
CE 645L _FLUID MEC}IIINICS AND MACHINDRY
(Common to Aeronautical Engineering, Automobile Engineering, Mechatronics
Engineering, Meehanical and Automation Engineering and Production Engineering
and also common to Fourth Semester Ind.ustrial Engineering, Industrial
Engineering and Management and Manufacturing Engineering)
. l:
' (Regulation 201"3)
fime: Three hours
Ahy rnissing data cair be suitably assumed.
I
Answer ALL questions.
.,
I ' Calculate the masb density and spqcifrc volume of, one litre of a liquid which
weighs7 N. i
q
What is the us6 of control volume?
3. Write the expression for calculating the Ioss d.ue to sud.den expansion of the
pipe.
4. . Give the classifrcation of boundary layer flow based on the Reynolds number.
5. Write the d.imension of surface tension and vapour pressure in MLT system.
6. What are lhe similitudes that shoul{ exist between the modgl and its
prototype?
7. Defrne the manometric effrciency and the mechanical effrcierley of a pump.
8. What are operating charactcristic curves of centrif,ugal pump? I
-9 \
''t
9.. Distinguish between an impulse turbine anb. a reaction turbine. : .
.:
10. Define specific speed and unit,speed'of a turbine.
PAF.T B (5 X 16 = 80 marks)
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11. (a) If the velocity fistribution of a fluid ove! a plate is given by u=ayz +by+c
with the vertex 0.2 m from the plate, where the veloeity is 1.2 m/s.
Calculate the velocity gradients and shear stresses at a distance of 0 m,
0,1 m and A.2 m from the plate, if the viscosity of the
fluid is 0.85 Nslm2.
(b) A pipe 200 m long slopes down at 1 in 100 and tapers from 600 mm
diameter at the higher end to 300 mm diameter at the lower end, and
carries 100 litres/sec of oil having specific gravity 0.8. If the pressure
gauge at the higher end reads 60 kN/m2, determine the
velocities at the two ends and.also the pressure at the lower end. Neglect
all losses.
L2. '(a) OiI flows through.a pipe 150 mm in diameter and 650 mm in length with
a velocity of 0.5 m/s. If the kinematic viscosity of oil is 18.7 x l0-amt/s, tl
frnd the no*", lost in overcoming friction. Take the specific gravity of oil
as 0.9.
Or
(b) A pipe line of 0.6 m diameter is 1.5 km 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 Darcy's friction factor is 0.04. The head.at inlet is 300 mm
Using Buckingham zr method of dimet''sional analysis obtain an
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13. (a)
expression for.the drag force R on a partially submerged body moving
with a relative velocity V in a fluid; the other
variables being the linear dimension L, height of surface roughness K,
fluid densi$ p and the gravitational acceleration g.
Or"
(b) The efficie rlcy q of a fdn depend.s on the density p , the dynamic viscosity
p of the fluid, the angular velocity ar, diameter D of the rotor and the
V
fischarge Q. Express 4. in terms of dimensionless parameters. Use
Rayleigh's method.
14. (a) A centrifugal pump has an impel.ler'500 mm in diameter running at
400 rpm. The discharge at the inlet is en'tirely radial. The velocity of the
flqw at outlet is 1 m/s. The vanes are curved backwards at outlet at 30o to
the wheel tangent. If the discharge of the pump is
0.14 m3/s, calculate the impeller power and, the torque on the shaft.
:_ : tor
(b) Explain with a neat sketch the working of a single"acting reciprg-cating
pump. Also obtain the expression for geisht of water delivered iby the
pump per second
77070
15. ' (a) ,,Draw'inlet and oullet veloeity triangle-s for a Pelton turbine and iridicate
the direction of various velocity .o-porr"rrts. Also obtain an expression
. for the work done' per seoond by water on the runner of the Pelton wheel.
Or
(b) The'ltu'b diameter of a Kaplan turbine working under a hea-$ of 12 m,-is
0.35 times the diameter of the runner. The turbine is running at
15o and fl.ow ratio is 0.6, find the diameter of the runner, diameter of the
r boss hnd the discharge through the runner. The velocity at the whirl at
outlet is given as zero.
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:77070
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