Tuesday, April 25, 2017
Roll No. ......................
Total No. of Questions : 09]
B. Tech. (Sem. – 4th)
APPLIED
THERMODYNAMICS - II
SUBJECT CODE : ME –
208 (2008 Batch)
Paper ID : [ME210]
Time : 03 Hours
Instruction to Candidates:
1) Section - A is Compulsory.
2) Attempt any Four questions from Section - B.
3) Attempt any Two questions from Section - C.
Section – A
Q1)
a) What is the function of carburetor.
b) Explain why the cooling of IC Engine is necessary.
c) Explain the term slip and power input factor as applied
to centrifugal
compressor.
d) Explain the phenomenon of 'surging' in a centrifugal
compressor.
e) Explain the term polytropic efficiency of compress or
(2), | .
f) What advantage is gained by splitting the turbine section
of a gas turbine
into two parts, namely compressor turbine and power turbine
(3).
g) Compare a gas turbine with a steam turbine (2).
h) Explain the term Octane number (2).
i) Compare gas turbine and reciprocating engine.
j) What is 'Morse Test'.
Section - B
Q2) Draw the valve timing diagram for an average petrol
engine. Give reasons for
early opening of exhaust valve and late closing of inlet
valves.
Q3) The following data refers to a test on a single cylinder
oil engine working on
fbur stroke cycle:
Diameter of-brake wheel = 60 cm; rope dia= 3 cm; the dead
load is 25kg,
when the spring balance reading is 5 kg, and the engine is
running at400 rcvl
min. The indicator diagram has area : 4 cm2,length
: 6cm and spring
stiffness is 12. The fuel consumption is 0.23kglb.h.p.-hr.
and the fuel used
has a calorific value 10500 kcal/kg. Taking cylinder bore 10
cm and piston
stroke l5 cm calculate the B.H.P., I.H.P., mechanical and
indicated thermal
of the engine.
Q4) l)describe the function of impeller and diffuser in
centrifugal compressor.
Q5) The centrifugal
compressor of a gas turbine requires 3000 H.P. when running
at 16000 rev/minute.
The tip diameter of the impeller is 50 cm and the uniform
width of casing of the vortex chamber between impeller and
diffuser is 49rn.
Measurements show that static pressure and temperature at a
radius of 27
cm are 2.5 kg, /cm and I10"C. The atmosphere in the
test house is I
kg,.icn-r2. Assuming slip factor:0.94 and neglecting
friction in the vortex
chamber. calculate :
(a) The mass flow l
( b) 'fhe resultant speed at the section given
(c) The total temperature at the section given
tt may be assumed that there is no prewhirl and the
conditions in the vaneless
space correspond to those of free vortex.
Q6) An axial compressor has a degree of reaction of 0.5 at
the mean radius with
relative air angles of I 30" and l00u at rotor inlet
and outlet respectively. The
angles are measured in the same direction from the blade
velocity direction.
The overall stagnation pressure ratio is 3.5 and the
stagnation isentropic
efficiency is 85% when the inlet stagnation temperature is
330 K. The blade
speed is constant at 200 m/s and the flow velocity is also
constant in the
compressor. The work done factor is 0.85. Find the
stagnation polytropic
efficiency and .the number of stage.
Section - C
Q7) In a gas turbine plant, air is compressed from
atmospheric conditions to the
delivery pressure 4bar and temperature 480 K. In the
combustion chamber,
a fuel of calorific value 45000 kJ/kg is injected and
combustion takes place at
consmnt pressure. The injection of fuel is so regulated that
the air fuel ratio is
60 : I . f,or a mass flow rate of l0kg/s design the turbine
e nozzle for throat and
exist areas. The maximum temperature of blades is to be 873
K. Take
cp =1 .005 kJ/kg and =1.4 both for air and gases. p
QS) Write a note on any two of the following :
(a) Ramjet
(b) Turbo prop
(c) Supercharging of IC engines
Q9) A four cylinder, four stroke engine is supplied with
l5.25 kg of air/kg of octane fuel having heat value 10650 kcal/kg. Calculate
(a) the compression
ratio. (b) brake specific fuel consumption, (c) bore and
stroke; (d) b.m.e.p.
The following data may be assumed :- air standard
efficiency:0.53, relative efficiency : 0.70, mechanical efficiency : 0.g;
volumetric efficiency : 0.g; stroke equal 1.25 times the bore ; suction
conditions are I kg/cm and 60"C the engine runs at 2400 rev/min and
develops 96 brake power.
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