Turbo-charging of I.C. Engines P M V Subbarao Professor Mechanical Engineering Department Going for...
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Turbo-charging of I.C. Engines P M V Subbarao Professor Mechanical Engineering Department Going for Artificially Breathing Engines….
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Transcript of Turbo-charging of I.C. Engines P M V Subbarao Professor Mechanical Engineering Department Going for...
Turbo-charging of I.C. Engines
P M V SubbaraoProfessor
Mechanical Engineering Department
Going for Artificially Breathing Engines….
Turbocharger
Matching of Turbocharger with Engine
• I.C. Engines are semi-control volumes.• Can accept or deliver flow across the boundary
intermittently.• Turbocharger is a combination of two pure control
volumes.• They need to continuously accept and deliver flow
across boundary.• Demands a special engineering art called as tuning.• An art of tuning CVs with CM.
– Fluid Dynamic Turning.– Thermodynamic Tuning.
The Problem of Fluid Dynamic Tuning
Т
C1
2 3
4P1, T1
P2, T2P3, T3
P4, T4
Engine
Turbocharged engine with Reservoirs
Thermodynamic Tuning
ТC
1
2 3
4P1, T1
P2, T2P3, T3
P4, T4
Engine
Compressor Sizing
• A compressor is sized based on two pieces of information, boost pressure and airflow.
• The desired boost pressure is chosen based on the performance objectives.
• The minimum boost pressure needed to achieve the performance objectives is to be evaluated.
• The airflow is directly related to the engine speed and is thus calculated based on what part of the speed range is desired to experience a power increase.
• Once the boost pressure and airflow are known, they are used to size the compressor.
• A compressor works best at a particular combination of airflow and boost pressure.
A comparison of this optimal combination of boost
pressure and airflow for a given compressor to the
Engine anticipated combination of boost pressure and airflow
determines the suitability of the compressor for the
system.
The First Law of Tuning
Thermo-fluid Dynamics of Compressor
Radial Flow Compressor Mixed Flow Compressor
Geometry of Turbo-compressor Wheel
s
T
T01
p01
T02=T02i
p02=p02i
0102
1122
TTcm
rVrVmP
isp
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Thermodynamic View of a Real isentropic Compressor
p
ia
c
V
2
22
p2i
0102 TTcmP p
p
a
c
V
2
22
p2
Only Impeller can consume Power !!!
p
a
c
V
2
21
p1
Only Impeller can consume Power !!!
1122 iiwiiw rVrVmP
iipii TTcmhhm 01020102
