marine engine

EFFECT ON ENGINE OPERATION:

*Shortage of scavenge air

*LOW SCAVENGE AIR  PRESSURE 

POWER LOSS

T/C SURGING 

HIGH EXHAUST TEMP

marine diesel engine Gas pressure

a

HOW GAS CAN RISE THE PRESSURE HIGHER THAN ITS OWN:

Gas pressure rotate the turbine compressor 

rotate &air induced to the eye of the impeller

*Due to centrifugal force at high speed air is through the diffuser 

*Diffuser convert the kinetic energy to pressure energy to volute casing 

*volute convert that the rest kinetic energy of air to pressure energy, thus air leaves the compressure  will high pressure then the gas pressure .

marine diesel engine turbo surging

 Advantage of super-surging:In crease scavenge efficience
*Increase mechanical efficience
*Increase thermal efficience
*Improve cooling efficience
*Reduce specific fuel conjumption 
*Better combustion 

   
SURGING:  
It is excess areodynamic  pulsation is air steam .when the discharge volute pressure exceedes  
the pressure build up in the diffuser & impeller 
it produces a back flow of air from discharge to suction &it is characherized by noise &vibrate of 
turbo surger speed  its called surging 

 SYMPTON:
Noising at the T/C
Gulping air sound at the compressor
Howling or banging noise

CAUSE:
&*Scavenge space fre
*Exhaust trunking fire
*Poor power balance 
*Fault turbine nozzle blade 
*Suddenly load change 
*Individual cylinder misfire
*Chocked scavenge ports 
*Governor shut the fuel off

diesel engine turbo charger suction filter

 CONSTANT PRESSURE TURBO SURGING:    

Advantage:
Exhaust piping are sample
*Higher turbine efficience
*Good performance at high load
Disadventage:
*Required auxiliary blower during maneuvering 
*Poor response to charge in load 
*












  

SUCTION FILTER:
A vacuum gauge or u-tube gauge is fitted on the suction side of the blower .so thst the inlet air  pressure between the filter &blower can dirty 
its resistance to air flow increase & pressure drop 
across the filter  is increased.