Surge Line

[munichstudent]

Sorry, I think I am abusing the purpose of this forum, but I really need some clear explanation as I'm trying to study jet propulsion in German and finding it damn difficult!

Basically I have a graph showing working line and stall (surge) line characteristics in a jet engine compressor. y axis is pressure ratio and x axis is dimensionless mass flow.

Can someone please explain what happens upon breaking the surge line, I think there was some talk of mass flow rate after this changing direction but I'm a bit lost...

Even any suggestions to where this is explained online would be great.

Many thanks.

 

[munichstudent]

I have just read the welcome email for this forum and noticed the "lazy student posting homework" bit... please note I am NOT being lazy here just cant seem to get this into my head what happens at and after the surge line, if there was an explanation i could find that looked clear i would happily read it through!

thanks again.

 

[dwedel]

Yes, the flow reverses. You are trying to push gas from a low pressure bottle to a high pressure bottle using centrifugal "forces" and the high pressure momentarily overcomes the centrifuge. As you are close to steady state conditions the flow will go back and forth across the line and destroy a rotor that may be spinning in excess of 20,000 rpm. Fecal matter hits the rotary oscilator.

Good luck with your studies,

dwedel
Hotrod Big Engines!
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[abeltio]

munichstudent
the subject has been discussed thoroughly here.
do a search for:
compressor surge

this search gave me 71 results today.

also, check google it has more than 80,000 results for compressor surge.

good luck.
gracias.

saludos.
a.

 

[munichstudent]

Thanks guys.

When I search for "compressor surge" i cant get any results.

?!?!?!

 

[abeltio]

click on search in this page
make sure you select:

Keyword(s): compressor surge
Scope Full Site (All Topic Areas)
Use All Words
Area Forums
Fields Full Text
When Any Date

this gives all the threads that contain compressor surge

saludos.
a.

 

[munichstudent]

me again.

the point of a booster is to compress the air flow in a turbine, it should therefore affect the mass flow rate shouldn't it? are there cases where it doesnt?!