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CODE NO:
R09220303
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R09
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SET No - 1
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II
B.TECH - II SEMESTER EXAMINATIONS, APRIL/MAY, 2011
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APPLIED
THERMODYNAMICS – I
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Time: 3hours
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(MECHANICAL
ENGINEERING)
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Max. Marks: 75
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Answer
any FIVE questions
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All
Questions Carry Equal Marks
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-
- -
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1.a) Derive the equation for efficiency of
diesel cycle.
b)
A
four stroke diesel engine has a bore of 25 cm and stroke of 40 cm. Cut off
takes place at 8% of the stroke and initial pressure of the cycle is 0.1 MPa.
Calculate the air
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standard
efficiency, m.e.p. and power developed by the engine if it is running at
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400 rpm.
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[7+8]
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2.a)
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With the help of a line
diagram, explain the fuel atomizer.
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b)
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Differentiate between indicator
diagram and valve timing diagram.
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[7+8]
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3.
With
all minute details, explain the factors affecting the knocking including the
fuel
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characteristics for S I Engines
and C I Engines.
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[15]
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4.a)
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With the help of diagrams,
explain different combustion chambers used in CI engines
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and advantages of each.
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b)
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What is meant by delay period
and explain factors affecting the delay period.
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[8+7]
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5.a) Derive an equation for the work done in
single stage reciprocating compressor neglecting the clearance volume.
b)
Air at 1 bar and 270C is taken into
single stage single acting reciprocating air compressor with law of pv1.1 = constant to a
final pressure of 7 bar and compressor takes 1 m3/min. Calculate
the indicated power and isothermal efficiency. Also calculate the cylinder
dimensions and power of the motor required to drive compressor. Speed of compressor is 5 rps. Stroke to bore
ratio 1.5:1, ηmech = 85%,
ηtransmission =
90%.[7+8]
6.
A
4 cylinder 4 – stroke petrol engine having bore 6 cm and stroke
10 cm develops 65 N-m torque at 3000 RPM. Find the fuel consumption of the
engine in kg/hr and brake mean effective pressure, if the relative efficiency
of 50% and clearance volume
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is 60 cm3. Take CV = 40
MJ/kg.
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[15]
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7.a) Explain the working details of steady flow
rotary compressors and p – v curves of the same.
b)
Derive
the equation for the thermodynamics cycle work done for a rotary compressor.
[8+7]
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8.
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Write short notes:
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a) Fuel rating methods.
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b) p-θ diagrams in Engine
testing.
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c) Velocity triangles for axial
flow compressor.
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[15]
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********
1.a) Define mean effective pressure and explain
its significance and measurement in an I.C. Engine.
b)
A fiat car working on Otto cycle has
initial pressure and temperature of 1 bar and
250C
and pressure at the end of compression is 10 bar. Calculate the percentage
clearance and thermal efficiency of the cycle. Also calculate the mean
effective
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pressure if
the maximum pressure of the cycle is limited to 20 bar.
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[7+8]
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2.a) Compare and contrast the valve timing
diagram and port timing diagram.
b)
With
the help of a neat diagram, explain the working of fuel injection system. [7+8]
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3.a)
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Explain the methods to control
the knocking in SI engines.
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b)
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Explain the significance of
Octane number in the rating of SI engine fuels.
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[7+8]
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4.a) What are factors which influence the delay
period in CI engines? Explain.
b)
What
are the requirements of CI engine combustion chamber? Explain why weak
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mixtures give
better efficiency in CI engines?
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[7+8]
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5.a) What is the effect of multistage compression
on volumetric efficiency of reciprocating compressor?
b)
In single stage single acting air
compressor of 30 cm dia, 40 cm stroke makes
100RPM.
It takes air at 1 bar and 200C
to a pressure of 5 bar. Calculate mean effective pressure and power required to
drive it when compression is isothermal and
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adiabatic.
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[7+8]
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6.
Following date refers to a four stroke
gas engine run for 1hr. RPM = 16,000; Missed cycles = 600; Net brake load = 1.6
KN; Brake circumference = 4 m; mep = 8 bar; Gas consumption = 22KL; CV of gas =
20 KJ/L; d = 25 cm; L = 40 cm; CR = 6.5;
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Calculate BP, IP,
bsfc, ηb.th and ηr .
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[15]
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7a)
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Give the analysis of
centrifugal compressors with the help of velocity diagrams.
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b)
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Explain the effect of Pre-whirl
in rotary compressors.
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[8+7]
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8.
Write
short notes on the following:
a)
Work
done factor in axial flow compressor.
b)
Measurement
of cylinder pressure.
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c) Anti knock
additives.
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[15]
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********
1.a) Why the dual cycle is also called as
limited pressure cycle? Compare it with diesel cycle.
b)
A
diesel engine with a compression ratio of 15 has initial temperature of 295 K
and
pressure of 0.96 bar. The heat
added at constant pressure up to 10% of the strike.
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Calculate the
air standard efficiency of the cycle and indicated power.
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[7+8]
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2.a) What are different methods are adopted in
cooling of an I.C. Engine? Explain in detail.
b)
Why
lubrication system is required in an I.C. Engine and explains one method with
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the diagram.
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[7+8]
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3.a) What is meant by knocking? Explain the
effects of knocking in SI engines.
b)
Explain
with the help of p-θ diagram, different stages of combustion in SI engines.
[7+8]
4.a) What are the different methods used in CI engines to create turbulence in the mixture?
Explain its effect on power output and thermal efficiency of the engine.
b)
What
are the factors which will affect the delay period in CI engines? Explain. [8+7]
5.a) Derive the equation for volumetric
efficiency and discuss the effect of clearance on volumetric efficiency.
b)
A single stage air compressor is
required to deal with 30 m3
of free air per ht at 1 bar.
The delivery
pressure at 450 RPM is 6.5 bar. Calculate clearance ratio, the IMEP, BP if the
mechanical efficiency is 0.8, isothermal efficiency is 0.76 and volumetric
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efficiency is
0.75.
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[7+8]
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6.
A
6 cylinder, 4-stroke petrol engine consumes 0.4 kg/min fuel when running at
4000RPM. Bore is 8 cm; Stroke is 10 cm. Clearance volume is 65 cm3. The torque
developed = 150 Nm. Calculate BP, BMEP, ηbreakethermal and ηrelative . CV = 40
MJ/Kg.
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[15]
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7.a)
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Draw the velocity triangles and
give the analysis of axial flow compressors.
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b)
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Explain the significance of
Degree of Reaction in axial flow compressors.
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[8+7]
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8.
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Write short notes:
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a) Exhaust blow down.
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b) Detonation and its effects.
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c) Heat balance sheet –
importance.
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[15]
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********
1.a) Compare Otto, diesel and dual cycles for
same maximum pressure and heat input condition.
b)
The temperature of air at the beginning
and end of compression of an Otto cycle are 310K and 600K. Calculate air
standard efficiency of the cycle if engine develops 20Kw indicated thermal
efficiency and relative efficiency. CV = 44MJ/Kg; Sp.gravity = 0.78. [7+8]
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2.a)
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Differentiate between air
standard cycle and fuel air cycle. What assumptions are
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made in analyzing fuel air
cycle?
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b)
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Explain with the help of line
diagram the working of a simple carburetor.
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[8+7]
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3.a) What is meant by ignition lag in SI
engines and explain the factors affecting the ignition lag.
b)
Explain
what is meant by abnormal combustion and knocking in SI engines in detail.
[8+7]
4.a) What is the effect of injection timing and
rate of fuel injection on diesel knock?
b)
Define
swirl, squish, directional movement and turbulence in CI engine. Explain their
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significance
in the design of CI engine combustion chambers.
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[7+8]
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5.a) What is the condition for maximum
efficiency in multistage compression.
b)
A single stage double acting air
compressor running at 5RPS delivers air at 7 bar from 1 bar and 270C.
The amount of free air delivered is 0.15 m3/s.
If the clearance volume is 5% of swept volume and index of
expansion/compression is 1.3. Calculate the volumetric efficiency, indicated
power and cylinder dimensions if L/D ratio as 1.2.
[7+8]
6.
A two stroke diesel engine was motored
when meter reading was 1.5 kW. Then the test on the engine was carried with
following results:
Brake torque = 120 N-m, RPM = 600; fuel used = 2.5
kg, CV of fuel = 41 kJ/kg;
cooling
water used = 820 kg. Rise in cooling water temperature is 1000
C. Exhaust gas temp = 3500C;
Room temp = 250C; A:F = 32:1;
Calculate BP, IP, Mechanical and
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indicated
thermal efficiencies and heat balances on percentage basis.
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[15]
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7.a) Derive the equation for polytropic
efficiency for a multi stage rotary compression.
b)
Derive
the equation for energy transfer between fluid and rotor of rotary compressor.
[7+8]
8.
Write
short notes:
a)
Work
done factor- significance in axial compressor.
b)
Determination
of FP.
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c) Detonation
and its effects.
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[15]
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********
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Code No: 07A4EC05
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R07
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Set No. 2
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II B.Tech II Semester
Examinations,APRIL 2011
THERMAL ENGINEERING - I
Common to Mechanical Engineering,
Automobile Engineering
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
c)
(a) Draw the velocity triangles for the
centrifugal compressor and derive the equa-tion for the estimation of power
required to compress the air.
What
are the function of lobes in Roots blower? Explain the working. [8+8]
d)
(a) Name the various measurements which are
to be taken in a test of an I.C. engine?
An
engine is used on a job requiring 110 kW B.P., the mechanical e ciency of the
engine is 80 % and the engine used 50 kg fuel per hour under the conditions of
operation. A design improvement is made which reduces the engine friction
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by 5 kW. Assuming the indicated
thermal e ciency remains the same, how
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many kg of fuel per hour will be saved.
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[6+10]
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3.
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Explain
swirl chamber, pre-combustion chamber, and air-cell combustion chamber
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in CI Engines.
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[16]
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4.
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(a) Clearly explain the various wet
sump lubrication systems?
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(b) Compare wet sump and dry sump
lubrication systems?
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[10+6]
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c)
Explain
di erent methods to achieve smooth engine operation in SI engines? [16]
d)
(a) Derive the equation for the work required
to compress the air to the desired pressure in axial compressor.
An axial ow compressor with compression ratio
of 5, draws air at 200C and delivers it at
500C.
Assuming 50% degree of reaction, nd the velocity of ow
if the blade velocity is 100 m/s. Also nd the number of stages if work factor
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=
0.85, = 100, = 400 and Cp = 1.005 kJ/kg K.
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[8+8]
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c)
(a) Derive an expression for the shaft work
of reciprocating air compressor assum-ing zero clearance volume.
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(b)
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Determine the minimum amount of work
required to compress the unit of
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mass of air from 1
bar 288 K to 40 bar, if the law of compression is pV 1:25
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= Const in a two stage
compressor with perfect inter cooling by neglecting the
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clearance.
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[6+10]
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8. (a)
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What are di erent factors a ecting
knock in SI engine?
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(b)
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What are knocking limited parameters
in SI engine?
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[8+8]
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? ? ? ? ?
1
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Code No: 07A4EC05
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R07
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Set No. 4
|
II B.Tech II Semester
Examinations,APRIL 2011
THERMAL ENGINEERING - I
Common to Mechanical Engineering,
Automobile Engineering
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. Explain swirl chamber,
pre-combustion chamber, and air-cell combustion chamber
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in CI Engines.
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[16]
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c) Explain di erent
methods to achieve smooth engine operation in SI engines? [16]
d) (a) What are di erent
factors a ecting knock in SI engine?
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(b) What are
knocking limited parameters in SI engine?
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[8+8]
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c)
(a) Derive the equation for the work required
to compress the air to the desired pressure in axial compressor.
An axial ow compressor with compression ratio
of 5, draws air at 200C and delivers it at
500C.
Assuming 50% degree of reaction, nd the velocity of ow
if the blade velocity is 100
m/s. Also nd the number of stages if
work factor
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=
0.85, = 100, = 400 and Cp = 1.005 kJ/kg K.
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[8+8]
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c)
(a) Name the various measurements which are
to be taken in a test of an I.C. engine?
An
engine is used on a job requiring 110 kW B.P., the mechanical e ciency of the
engine is 80 % and the engine used 50 kg fuel per hour under the conditions of
operation. A design improvement is made which reduces the engine friction
by 5 kW. Assuming the
indicated thermal e ciency remains the
same, how
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many kg of fuel per
hour will be saved.
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[6+10]
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c)
(a) Draw the velocity triangles for the
centrifugal compressor and derive the equa-tion for the estimation of power
required to compress the air.
What
are the function of lobes in Roots blower? Explain the working. [8+8]
d)
(a)
Clearly explain the various wet sump lubrication systems?
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(b) Compare wet
sump and dry sump lubrication systems?
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[10+6]
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8.
(a) Derive an expression for the shaft work
of reciprocating air compressor assum-ing zero clearance volume.
(b) Determine the minimum amount of work required to
compress the unit of mass of air from 1 bar 288 K to 40 bar, if the law of
compression is pV 1:25
= Const in a two stage
compressor with perfect inter cooling by neglecting the
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clearance.
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[6+10]
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? ? ? ? ?
2
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Code No: 07A4EC05
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R07
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Set No. 1
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II B.Tech II Semester Examinations,APRIL
2011
THERMAL ENGINEERING - I
Common to Mechanical Engineering,
Automobile Engineering
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1.
(a) Derive an expression for the shaft work
of reciprocating air compressor assum-ing zero clearance volume.
(b) Determine the minimum amount of work required to
compress the unit of mass of air from 1 bar 288 K to 40 bar, if the law of
compression is pV 1:25
= Const in a two stage
compressor with perfect inter cooling by neglecting the
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clearance.
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[6+10]
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2.
(a) Name the various measurements which are
to be taken in a test of an I.C. engine?
(b) An engine is used on a job requiring
110 kW B.P., the mechanical e ciency of the engine is 80 % and the engine used
50 kg fuel per hour under the conditions
of operation. A design improvement is
made which reduces the engine friction by 5 kW. Assuming the indicated thermal
e ciency remains the same, how
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many
kg of fuel per hour will be saved.
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[6+10]
|
3. Explain di erent
methods to achieve smooth engine operation in SI engines? [16]
4.
(a) Draw the velocity triangles for the
centrifugal compressor and derive the equa-tion for the estimation of power
required to compress the air.
(b) What are the function
of lobes in Roots blower? Explain the working. [8+8]
5.
(a) Derive the equation for the work required
to compress the air to the desired pressure in axial compressor.
(b)
An axial ow compressor with compression ratio
of 5, draws air at 200C and delivers it at
500C.
Assuming 50% degree of reaction, nd the velocity of ow
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if the blade
velocity is 100 m/s. Also nd the
number of stages if work factor
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= 0.85, = 100, = 400 and Cp = 1.005 kJ/kg K.
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[8+8]
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6.
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Explain swirl chamber,
pre-combustion chamber, and air-cell combustion chamber
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in CI Engines.
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[16]
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7.
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(a)
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What are di erent factors a ecting
knock in SI engine?
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(b)
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What are knocking limited parameters
in SI engine?
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[8+8]
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8.
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(a)
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Clearly explain the various wet sump
lubrication systems?
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(b)
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Compare wet sump and dry sump
lubrication systems?
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[10+6]
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? ? ? ? ?
3
|
Code No: 07A4EC05
|
|
R07
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|
Set No. 3
|
II B.Tech II Semester
Examinations,APRIL 2011
THERMAL ENGINEERING - I
Common to Mechanical Engineering,
Automobile Engineering
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1.
(a) What are di erent factors a ecting knock in SI engine?
|
(b) What are
knocking limited parameters in SI engine?
|
[8+8]
|
2.
(a) Clearly explain the various wet sump lubrication systems?
|
(b) Compare wet
sump and dry sump lubrication systems?
|
[10+6]
|
3.
(a) Derive an expression for the shaft work
of reciprocating air compressor assum-ing zero clearance volume.
(b) Determine the minimum amount of work required to compress
the unit of mass of air from 1 bar 288 K to 40 bar, if the law of compression
is pV 1:25
= Const in a two stage
compressor with perfect inter cooling by neglecting the
|
clearance.
|
[6+10]
|
4. Explain swirl chamber,
pre-combustion chamber, and air-cell combustion chamber
|
in CI Engines.
|
[16]
|
5.
(a) Draw the velocity triangles for the
centrifugal compressor and derive the equa-tion for the estimation of power
required to compress the air.
(b) What are the function
of lobes in Roots blower? Explain the working. [8+8]
6. Explain di erent
methods to achieve smooth engine operation in SI engines? [16]
7.
(a) Derive the equation for the work required
to compress the air to the desired pressure in axial compressor.
(b) An
axial ow compressor with compression
ratio of 5, draws air at 200C and
delivers
it at 500C. Assuming 50% degree of reaction, nd
the velocity of ow if the blade velocity is 100 m/s. Also nd the number of
stages if work factor
|
=
0.85, = 100, = 400 and Cp = 1.005 kJ/kg K.
|
[8+8]
|
8.
(a) Name the various measurements which are
to be taken in a test of an I.C. engine?
(b) An engine is used on a job requiring
110 kW B.P., the mechanical e ciency of the engine is 80 % and the engine used
50 kg fuel per hour under the conditions
of operation. A design improvement is
made which reduces the engine friction by 5 kW. Assuming the indicated thermal
e ciency remains the same, how
|
many
kg of fuel per hour will be saved.
|
[6+10]
|
? ? ? ? ?
4
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