Compressor Surge or Stall theory and beed valves opening during start up and shutdown

 

The 'Search' feature of control.com is very powerful, though this new version takes some getting used to.

Try searching for '+surge' (without the quotation marks) and you will quickly find many related articles.

This is one of the more recent:

http://www.control.com/thread/1231343625#1231414602

 

i couldn't get any information regarding compressor surge or stall. please give correct information.

 

Try searching the Internet for information about axial compressors. The bleed valves are used to protect against excessively high downstream pressures causing air to not be able to be passed downstream through the axial compressor.

Axial compressors ain't like most other equipment. Be prepared for a lot of formulae and equations.

 

One of the great engineering accomplishments of the 20th century was the development of axial flow compressors. Prior to their invention, centrifugal compressors utilizing large diameter wheels and casings were the norm, increasing the size and weight of these engines, many of which were for use in aircraft where size and weight are matter a lot.

The genius behind axial flow compression design was to overcome the natural tendency for the compressed gas to flow from higher to lower pressure or to reverse the desired flow direction. That tendency occurs in no small way during a compressor stall, which I understand to be a sudden, destructive reverse flow resulting from excessive back pressure in the higher compressor stages.

I think of the bleed valves as being air operated pressure relief valves that prevent the buildup of surge-causing back pressure by venting excess air from two of the compresser stages into the exhaust. The bleed valves stay open until the generator circuit breaker closes and they open the moment the GCB opens. That's my story and I'm stickin' to it.

 

Compressor stall is a situation of abnormal airflow resulting from a stall of the aerofoils within the compressor. Stall is found in dynamic Compressors particularly, as used in jet engines and turbochargers for reciprocating engines.

Compressor stalls result in a loss of compressor performance, axial compressors which can vary in severity from a momentary machine power drop occurring so quickly it is barely registered on machine instruments to a complete loss of compression (compressor surge) necessitating a reduction in the fuel flow to the engine.

 

well :
surge means: the air that swivel around the compressor ((a stage before stall occurs))

Stall: air that moves around the blades in advanced stage where it affects the engine and parameters!

so both are related but one comes before the other