CIAC Turbocharger Surging
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Turbocharger
Surging Balloon surge
Surging exemplified
Surging facts
Surging explained
Possible causes
Countermeasures
Design influences
Aerodynamic noise
SURGING !
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CIAC 42 / Ver 2.1 / 2 / July 2006
Turbocharger
Surging Surging facts
Surging exemplified Surging at high load should be avoided!
Surging facts Excessive loading of the rotating parts during surging can
Surging explained cause damage
Possible causes
The turbocharger speed may increase momentarily by
Countermeasures
about 15% during surging!
Design influences
Aerodynamic noise
There are three main causes of surging:
Flow restriction and fouling in the air/gas system
Malfunctioning of the engine fuel system
Rapid variation in engine load
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CIAC 42 / Ver 2.1 / 3 / July 2006
Turbocharger
Surging Surging facts
Surging exemplified Surging is usually caused by the air or gas flow being
Surging facts restricted in some way:
Surging explained Dirty air filter silencer
Possible causes
Increased backpressure after the turbine
Countermeasures
(dirty exhaust boiler or silencer)
Design influences
Dirty air side of charge air cooler
Aerodynamic noise
High charge air cooler water inlet temperature
Contaminated nozzle ring or turbine
A ship’s hull being dirty, causing the engine to run at
full torque / reduced speed
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Surging occurs in single stage TC installations or in multi
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TC installations, but is more likely to occur in the latter.
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CIAC 42 / Ver 2.1 / 4 / July 2006
Turbocharger
Surging Surging explained – normal conditions
Surging exemplified Pressure Under normal operating
Surging facts Operating point conditions, the turbocharger
Surging explained follows the operating line in
Possible causes Operating line accordance with three criteria:
Countermeasures
pressure ratio
Design influences
air volume flow
Aerodynamic noise
turbocharger speed
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CIAC 42 / Ver 2.1 / 5 / July 2006
Turbocharger
Surging Surging explained – normal conditions
Surging exemplified
High pressure - slow air speed
Surging facts
Surging explained
Low pressure - high air speed
Possible causes
Countermeasures The air flow follows
Design influences the directions
Aerodynamic noise determined by the
diffuser vane.
Diffusion takes place
and speed is
converted into
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pressure.
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CIAC 42 / Ver 2.1 / 6 / July 2006
Turbocharger
Surging Surging explained – flow restriction
Surging exemplified A reduction in air flow
Surging facts changes the velocity
Surging explained angles, causing the
Possible causes boundary layer to
Countermeasures break down.
Design influences
The resulting
Aerodynamic noise turbulence reduces
the free air flow area.
No diffusion takes
place, the air speed
remains high, i.e. no
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pressure is produced.
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CIAC 42 / Ver 2.1 / 7 / July 2006
Turbocharger
Surging Surging explained – surging
Surging exemplified
Low pressure - high air speed
Surging facts
Surging explained
Possible causes
Countermeasures Surging takes place
Design influences because the pressure
Aerodynamic noise downstream of the
diffuser is higher than
the diffuser pressure.
The air flow is
reversed.
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CIAC 42 / Ver 2.1 / 8 / July 2006
Turbocharger
Surging Surging explained – overview
Surging exemplified Pressure Normal operation
Surging facts
Surging explained
Possible causes
Countermeasures
Design influences Boundary layer
Aerodynamic noise breakdown. The
air speed is not
converted into
pressure.
Compressor flow
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reversal - SURGING
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CIAC 42 / Ver 2.1 / 9 / July 2006
Turbocharger
Surging Possible causes
Surging exemplified Fuel oil system:
Surging facts Low circulating or supply pump pressure
Surging explained
Air in fuel oil
Possible causes
Water in fuel oil
Countermeasures
Design influences
Low pre-heating temperature
Aerodynamic noise
Malfunctioning of deaerating valve on top of venting
tank
Turbocharger:
Fouled air filter/silencer
Fouled or damaged compressor side
CIAC home Fouled or damaged turbine side
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CIAC 42 / Ver 2.1 / 10 / July 2006
Turbocharger
Surging Possible causes
Surging exemplified Exhaust system:
Surging facts Exhaust valve not opening correctly
Surging explained
Damaged or blocked protective grating before turbine
Possible causes
Increased backpressure after turbine
Countermeasures
Design influences Scavenge air system:
Aerodynamic noise Fouled charge air cooler, water mist catcher and / or
ducts
Fouled water circulation to charge air cooler
Miscellaneous:
Hunting governor
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Rapid changes in engine load
Too rapid rpm change
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CIAC 42 / Ver 2.1 / 11 / July 2006
Turbocharger
Surging Countermeasures
Surging exemplified Temporary measures:
Surging facts Open relief valve on top of air receiver
Surging explained
Open one exhaust by-pass valve (if installed)
Possible causes
Keep auxiliary blowers longer in service
(surging during running up)
Countermeasures
Design influences
Aerodynamic noise Corrective measures:
Repair / correct the deficient part of the system
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CIAC 42 / Ver 2.1 / 12 / July 2006
Turbocharger
Surging Refer to engine builder’s manual
Surging exemplified
Surging facts
Surging explained
Possible causes
Countermeasures
Design influences
Aerodynamic noise
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CIAC 42 / Ver 2.1 / 13 / July 2006
Turbocharger
Surging Turbocharging system layout
Surging exemplified One turbocharger
Surging facts with single air
Surging explained receiver
Possible causes inherently stable
Countermeasures against surging
Design influences
Aerodynamic noise
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CIAC 42 / Ver 2.1 / 14 / July 2006
Turbocharger
Surging Turbocharging system layout
Surging exemplified Dual
Surging facts turbochargers with
Surging explained single air receiver
Possible causes inherently
Countermeasures unstable, i.e.
Design influences
the ‘stronger’ TC
Aerodynamic noise
or engine system
deficiencies may
cause the ’weaker’
TC to surge.
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CIAC 42 / Ver 2.1 / 15 / July 2006
Turbocharger
Surging Engine design influence
Surging exemplified
Pressure
Surging facts
Surging explained
Possible causes
Countermeasures
Design influences
Aerodynamic noise Crankshaft angle
Surging is also influenced by air pressure fluctuations.
Fewer cylinders or a smaller air receiver volume create bigger
fluctuations.
CIAC home An appropriate surge margin is important during initial
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matching of the turbocharger.
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CIAC 42 / Ver 2.1 / 16 / July 2006
Turbocharger
Surging Humming noise
Surging exemplified 5 Humming sound:
Surging facts
4,5 Experienced from
Surging explained
time to time, coming
4
Possible causes
from the compressor
Countermeasures
Design influences
3,5 During low load
operation, i.e. with a
Aerodynamic noise 3
low compressor
2,5 pressure ratio
2
Does NOT mean
surging is about to
1,5 begin!
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1 Has no influence on
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engine and TC
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CIAC 42 / Ver 2.1 / 17 / July 2006
