4. I.What is a turbocharger? Why is it
needed?
The turbocharger is an integral part of the ship’s marine engine as it reuses
the exhaust gases in order to increase the overall efficiency of the engine. It
consists of two parts – blower and turbine sides, which need equal
attention while carrying out routine maintenance procedures.
1)To generate more power we require more Fuel and Air.
Conventionally this was achieved by increasing length
of piston stroke or the number of cylinders.
2)Using Turbocharger we can generate more power from the
same engine at much lesser fuel as it would be
required by a new engine.
3)A turbocharger is so needed to provide that extra air
required for the proper combustion. This leads to an
advantage in the efficiency and power of the engine.
4)It is a device that really makes it possible to
5. CONSTRUCTION -
A turbocharger is a device consists of two
main parts turbine and compressor
mounted on the same shaft. On the basis of
its design all turbocharged engines can be
classified into two main types; Axial flow
and radial/centrifugal turbochargers.
1 ) Turbine
High-velocity exhaust gas from the
nozzle ring is directed on to the rotor
blades. Nozzle rings are used to
generate kinetic energy in exhaust gas
while rotor blades are held tightly by
roots of the fir tree structure. They
are secured from vibration by lacing
wires passing through each of them.
Heat resistant nickel-chromium steel is
used for the construction of turbine
blades, wheel nozzle, and shaft.
Adequate arrangement for cooling water
6. 2 ) Compressor / Blower
A compressor or blower is fitted with a set of silencer and filter at the inlet side of a
turbocharger.
To direct the flow of fresh air towards the center an inducer made of light alloy aluminum
steel is fitted just before the impeller. The impeller takes fresh air axially while delivers it
radially along with the volute casing.
A volute casing is placed just after the impeller to convert all that kinetic energy of the
fresh air into pressure energy. The pressurized air is then sent to the cylinder via inter
cooler to cool the compressed air.
3 ) Bearings & Seals
Separate shaft bearings are fitted on both parts of the turbocharger. Generally ball and
roller or plain sleeve bearings are used
The additional labyrinth seal is fitted in between the bearings and turbine & in
between thrust bearing and compressor blower. Labyrinth seals are sealed by air
discharge from the blower to avoid the risk of lube oil contamination from the
exhaust gas.
7. WORKING -
1)Fresh air is sucked in by the impeller of the blower via a set of fitter and inducer.
2)The blades of the impeller ( blower ) take the air axially while releases it radially.
3)The squeezed hot air is then passed through the volute casing to produce pressure.
4)This hot pressurized air is then passed through the inter cooler or so-called heat
exchanger.
5)A heat exchanger is used to cool down the air; thus increasing its density.
Compressed cool air helps burn more fuel thus producing more power for the shaft,
piston, and (propeller/wheels / Gear ) depending upon engine application.
6)More combustion leads to more exhaust which is then used to rotate turbine blades.
7)Nozzle rings are used to add high kinetic energy to the exhaust gas.
8)The turbine rotates turning the blower impeller along with the shaft.
9)The exhaust then leaves out of the system with much lesser waste heat then it would
otherwise.
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