It is a phenomena of irregular pulsation due to a change in mass flow with respect to pressure ratio,at this breakdown the pressure pulsation is relieved backward to the compressor.
Sudden pressure changes due to chocking or throttling effect causes a breakdown of mass flow.A back flow of air now takes place from scavenge manifold at higher pressure o the turbocharger compressor side at a lower pressure. The reverse flow tend to drive the turbocharger in the opposite direction and partly stall it. This is repeated until air demand is increases and stable condition is achieved
IN SHORT-Air flows in reverse direction in a surge due to higher pressure at the scavenge manifold than the turbo charger compressor
Symptoms
- gulping air sound at compressor intake
- violent pressure fluctuation in scavenge pressure
- howling/banging noise
Causes
- Fouling of air intake filter
- fouling of compressor turbine wheel,nozzle ring,EGE
- Sudden load change during maneuvering /overloading/crash astern condition
- Rough Weather
- fuel starvation,faulty fuel pump,fuel injector, severely wrong pump timing
Action
- Dirty air intake to be replaced or cleaned
- Regular cleaning of turbocharger (air and exhaust side)
- proper matching of turbocharger to the engine with respect to the compressor map characteristics