A turbocharger is a device consisting 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. An axial flow turbine setup is more popular on ships.
Parts of turbocharger
Nickel-chromium steel is used for the construction of turbine blades and has heat-resistant properties. High-velocity exhaust gas from the nozzle ring is directed to the rotor blades.
Nozzle rings are used to generate kinetic energy in the exhaust gas. They are secured from vibration by lacing wires passing through each of them.
Compressor / Blower:
A compressor or blower is fitted with a set of silencers and filters at the inlet side of a turbocharger. It is attached to one end of the shaft, whose other end is connected to the turbine, which rotates the blower. An inducer made of light alloy aluminium steel is fitted just before the impeller.
The impeller takes fresh air axially while delivering 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, which is then sent to the cylinder via intercooler for combustion.
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 ( 1st set) & in between the thrust bearing and compressor/blower ( 2nd set ).
Labyrinth seals are sealed by air discharged from the blower to avoid the risk of lube oil contamination from the exhaust gas.