lecture 2 - engine kinematics.ppt
TRANSCRIPT
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KINEMATICS OF COMBUSTION ENGINES
Reciprocating Engine
•The pressure forces of the working fluid acting on the piston are transmitted directly to the crankshaft via piston pin and connecting rod
Configuration of Engine
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Displacement of crank radius
Displacement of connecting rod
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Define:
Using Trigonometry Law:
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0 1 2 3 4 5 60
10
20
30
40
50
60
70
80
Crank Angle (Rad)
Pist
on D
ispl
acem
ent (
mm
)
Lamda s = 0.9
Lamda s = 0.5
Lamda s = 0.2
a) Piston Travel
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b) Piston Speed
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::
{For small lamda - s}
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0 1 2 3 4 5 6-5000
-4000
-3000
-2000
-1000
0
1000
2000
3000
4000
5000
Crank Angle (rad)
Pis
ton
Spe
ed (
mm
/s)
Lamda s = 0.5
Lamda s = 0.3
Lamda s = 0.1
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c) Piston Acceleration
For the approximated formula:
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Design of Flywheel
Assuming Rigid Shaft
Ti To
Primarily we want to know the overall performance of the flywheel.
-What should its moment of inertia be? -How do we match the power source to the load? -And what are the resulting performance characteristics of the system that we have selected?
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An Example of a Flywheel Operating Conditions:
• A flywheel receives energy under a constant torque causing its shaft to rotate from 1 to 2. (Positive Torque)• The shaft rotates from 1 to 2. • The shaft rotates constantly from 2 to 3, under no torque.• The flywheel gives out energy under constant torque to operate a load.• The shaft speed drop from 3 to 4.
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