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TRANSCRIPT
VOLUME - 3
I.C ENGINE, ENGINEERING MECHANICS, FLUID
MACHINERY
IES/GATE
MECHANICAL ENGINEERING
Index
IC Engine
1. Basics and air standard cycles 1
2. Combustion in SI & CI Engines 82
3. Supercharging 101
4. Carburation & Fuel injection 106
5. Thermochemistry and Fuels 124
Engineering Mechanics
1. System of forces 138
2. Equilibrium 149
3. Plane trusses 153
4. Work, energy and virtual work 165
5. Kinematics of point mass & rigid bodies 169
6. Friction 177
7. Impulse, momentum & Collision 184
Fluid Machinery
1. Introduction to fluid Machinery (Impulse of Jet) 202
2. Hydraulic Turbines 220
3. Hydraulic Pumps 261
1
2
Piston pin/ Gudgeon kin (G) :-
- It is subjected to pressure loading condition (Completely reversed coding cycle), Hence it should be made up of forged steel
- In clear to remove surface defects it is undergone machining
Note: - connecting rod and crank rod is also made up of forged steel but specially
by drop forging (cold)
To remove internal defects
3
It should be smooth and brittle
Brittle because if it is ductile after some usage line it will deform and create a space from where AFM may leaks out
This is called as blow by defeat
π·πππ
πΆππππππππ πππ‘ππ = π =ππ
ππ < 1 It is the ratio of the volume which is not
Covered by piston to the volume which Is covered by the piston and It is Generally Len than 1 β΄ [πΆ < 1]
4
π > 1 = ππππ
πΏππ π
π»π
πͺππππ ππππ 7DC
πͺππππ BOC
π»π
πΆππππ . ππ =π2
π1 ππ =
π2
π1 ππ =
π£1
π£2
ππ₯πππππ =π3
π4 ππ =
π3
π4 ππ =
π4
π3
5
6
7
8
Otto Cycle: [constant volume heat addition cycle air standard cycle for petrol engine]
(1) Air is working fluid (2) Air is perfect gas treated as ideal gas [ππ£ = π π] ππ΄πΉπ >> πππ‘π
πΆπ > πΆπ£&π = ππππ π‘πππ‘
πππππ β
ππππ₯
πΆπ»4 + 2 [π2 +79
21π2]
πππππ β πΆπ2 + 2π»2π + 2 Γ
79
21π2 + βπ» + βπΆ
9
10
Mean effective Pressure :-
l π΄πππ π πππ
ππ βπ
πΏπ v
(π)
Mean Effective pressure :- It is a mathematical to determine an
imaginary pressure which will gives us the mean work done like the work
done of the actual cycle for the same change in volume (Swept volume)
GATE 2004:- Sq. Engine βπΏ
π· = 1: 1
Ques. Sq. engine βπΏ
π· = 1.5
An engine working on Otto cycle and bore 10cm and stroke is of 15m with
the clearance volume of 196.3cm and the adiabatic index of the air is 1.4.
The heat added is 1800KJ/Kg
(i) Find the work done per kg
(ii) Determine the mean effective pressure of the cycle 0.001 kg of the working
fuel
Solution:-
π· = 10ππ
πΏ = 15ππ
ππ = 196.3ππ3
π = 1.4
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π =1800πΎπ½
πΎπ
π =?
ππ =?
ππ =β
π’π2πΏ = 1178.09ππ3
πΆ =ππ
ππ = 0.167
π = 7602
β« = 1 β (1
1π)
πβ1
=(π)β?9π§6.5ππ.
π»π΄|
1800
= 59.09%
(ππ)πππ‘ = 973.5 1π./1π.
(ππ)πππ‘ = ππ ππ
973.5 = ππ 1178.09.
ππ = 0.826 πΎππ
ππ = 0.08 πππ
End of Exhaust and beginning of section :-
TOC (πππππ)
Exhaust gases
NTEE TOC
(Mean to
End of
Exhaust) ππππππππ β π΄πππ β
πππππππ(ππππππ ππππππ
BDC
12
β Due to the piston movement during the exhaust stroke (at the very near of
exhaust) The exhaust value is closed then due to the compression of exhaust
gas, the pressure inside the cylinder will increased
πΌπ°π° =π¨
π»=
π½π
π½π= πΌπ½ππ.
π½π =β
ππΆππ³
π·ππ½π = πππΉπ»π
β Hence at the beginning of the section stroke as the inlet value is open but
still No entry of the fresh air AFM into the cylinder ( From inside the cylinder
is above ATM) [ππ > πππ‘π] @ [ππ·πΆ π‘π π]
β Due to the expansion of compression exhaust gas its pressure lowers down
and reaches to Patm.
[Then after fresh AFM start entering]
13
Volumetric efficiency: - (Explained Above)
It is the ratio of actual section volume of air that actually entering into the cylinder
during section strike to the theoretical section volume
ππΌπΌ =π΄
π=
ππ
ππ = ππ£ππ.
NOTE: - {exhaust stroke} βScavengingβ
(95% +)ππ₯ππππππ πππ
πΈπ₯βππ’π π‘ ππ‘ππππ ππβ«πππ‘π
πππππππ πππ (π%β)ππ₯βππ’π π‘ πππ ππ
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(2) # βDiesel cycleβ or Cost perm Heat addition cycle:-
π20 = 619π (Spark plug)
ππ β6β π‘π 12
ππ β 16 π‘π 22β
π20 = 1033π (> ππ ππ¦19.)
π·πππ ππ
ππππππ
πππ’π‘β
π ββΓ π β
(π£πππππ‘πππ & ππππ π)
πΏππ΄π·π. π. ββ πΏπ’π₯π’ππ¦ ββ
ππ΄π ββ
NOTE: π°π¬πΊ (π»ππππ πππ. )π πππππ < (π»ππππ πππ. )ππππππ
0
0
0
0
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