Aces High Bulletin Board

General Forums => The O' Club => Topic started by: Seagoon on October 27, 2005, 10:10:24 PM

Title: Compressor Blade Stall?
Post by: Seagoon on October 27, 2005, 10:10:24 PM
Hi Guys,

Was reading about the physics of various Jet Engines today and was interested to note how various air intakes in fighters are designed to "separate the air flow" so that the air that has been slowed down via friction from contact with the fuselage isn't sucked in. One of the reasons this is important, I learned, is that it can lead to "compressor blade stall" which is apparently very, very, bad.

Can someone explain what Compressor Blade Stall is and a brief explanation of the physics involved, keeping in mind that I failed Algebra twice in a row. ;)

Thanks!

SEAGOON
Title: Compressor Blade Stall?
Post by: Dago on October 27, 2005, 10:13:39 PM
In a nutshell, when the airflow momentarily stops or reverses direction in the compressor (front) section of a jet engine.  

Can sound very dramatic.  Can make flame shoot out the back of the engine (and front too in some stalls).

Doesnt often result in damage, but is some cases it can, including bending compressor blades.

dago
Title: Compressor Blade Stall?
Post by: Charge on October 28, 2005, 05:40:48 AM
http://www.centennialofflight.gov/essay/Evolution_of_Technology/jet_engines/Tech24.htm


http://www.grc.nasa.gov/WWW/RT2000/5000/5810suder.html


This was very good:

http://en.wikipedia.org/wiki/Compressor_stall

-C+
Title: Compressor Blade Stall?
Post by: Dinger on October 28, 2005, 06:31:02 AM
Yup. Big bang, flames shoot out, plane lurches like somebody smacked it with a baseball bat. Passengers break out in derisive applause. Nobody speaks of it again.
Title: Compressor Blade Stall?
Post by: Heater on October 28, 2005, 09:06:02 AM
A "blade stall" is not as bad as a full compressor stall, and yes you can have both, as a stall is a disruption of the airflow.

and a bad stall looks somthing like this,

(http://www.xs4all.nl/~heater1/blowout.jpg)

this is actuly an "Afterbunner blowout" but  stall will produce the same effect, but it comes out both ends
Title: Compressor Blade Stall?
Post by: Ripsnort on October 28, 2005, 10:06:57 AM
Sadly, this is what ended Bong's life at a critical time inflight,  just after crossing the runway boundary on take off, at 60 feet in the air. :(
Title: Compressor Blade Stall?
Post by: Habu on October 28, 2005, 09:08:21 PM
Who was Bong?
Title: Compressor Blade Stall?
Post by: Simaril on October 28, 2005, 10:08:26 PM
Quote
Originally posted by Habu
Who was Bong?


You know, trolls are against the rules....
Title: Compressor Blade Stall?
Post by: Roscoroo on October 29, 2005, 05:22:15 AM
A flame out in a "combustion can" along with a sudden explosion of raw fuel can cause a full compresser stall . "Variable stator bladed" compressers also comp stall fairly easy .  its a noise that you dont forget thats forshure.
Title: Compressor Blade Stall?
Post by: Lye-El on October 29, 2005, 11:49:36 AM
Had a Cobra helicopter compressor stall on run up once. Chug, chug, chug...fire out the doghouse, aircraft slewed on the pad. Was impressive.


When the sargent started to back away from the aircraft the two Spec 4s standing there (me being one) unassed the A.O. i.e. we started to run until we heard the engine start winding down.  

The whole drive train was replaced from engine to tailboom from being overstressed.
:O