Compressor Stall?

[flyboyzz1]

Hey all just wanted to know what a compressor stall/ surge is. Any help?

 

[G200_PILOT]

It's when the fan in your air conditioner's compressor (outside your house) stops spinning. You have to go outside and hand prop it to start it again.

 

[ultrarunner]

In simple terms, turbine blades in a turbine engine require correct airlfow over them in order to operate efficiently...much like a wing.

When this airflow is disrupted, such as with extreme angles of attack, inadequate airflow, etc.. the compressor (s) (blades) will stall....

It commonly occurs when take off thrust is applied and a sudden cross wind occurs across the engine inlet, disrupting the airlow. Lots of banging and erratic engine indications.

Another common occurrance is when a flight crew attempts an engine start at or very near the tail-wind component limit for starting.


Compressor stalls can also occur during flight. And a classic example is the RJ that crashed several months ago after a dual flame-out.

Hope this helps you a bit.

 

[ultrarunner]

It's when the fan in your air conditioner's compressor (outside your house) stops spinning. You have to go outside and hand prop it to start it again.

Hey dude, shouldn't you be at a picket line that no one cares about?

Yeah, I thought so.

 

[Dangerkitty]

Hey dude, shouldn't you be at a picket line that no one cares about?

Yeah, I thought so.

Too funny!

 

[flyboyzz1]

In simple terms, turbine blades in a turbine engine require correct airlfow over them in order to operate efficiently...much like a wing.

When this airflow is disrupted, such as with extreme angles of attack, inadequate airflow, etc.. the compressor (s) (blades) will stall....

It commonly occurs when take off thrust is applied and a sudden cross wind occurs across the engine inlet, disrupting the airlow. Lots of banging and erratic engine indications.

Another common occurrance is when a flight crew attempts an engine start at or very near the tail-wind component limit for starting.


Compressor stalls can also occur during flight. And a classic example is the RJ that crashed several months ago after a dual flame-out.

Hope this helps you a bit.

Thanks!

 

[G200_PILOT]

Hey dude, shouldn't you be at a picket line that no one cares about?

Yeah, I thought so.

Plenty of people care. But thanks for your opinion. Tell you what. If you're such a tough guy, why don't you email me your name. Just your name, nothing else. But you have to be honest about it. That way, when your airplane gets sold out from underneath you because your boss decided to goto to NetJets or dies, or goes out of business.... I'll remember your name when you apply and come in for an interview. You see, this is a small industry. We all win run into one another someday. If you're man enough to give me your name, I feel sorry for you if you ever think of applying to us or say... Southwest. You see, Southwest is full of ex-Netjets pilots and once a name is put on that blacklist, you're done.

You sound like a SCAB or a potential SCAB to me by making comments about a brother picketing for what he believes in.

So how about it? Got balls?

 

[ultrarunner]

Thanks!

NO Prob flyboy...

Here is another reference that has a good discussion about it. Knowledge is power...

enjoy the reading...

<http://scholar.lib.vt.edu/theses/available/etd-92798-3849/unrestricted/etd2.pdf>

 

[minitour]

When this airflow is disrupted, such as with extreme angles of attack, inadequate airflow, etc.. the compressor (s) (blades) will stall....

I don't understand this a lot and haven't found anything in books to really explain it.

Okay...so if you're flyin along in a 152 and yank back as hard as you can, you'd stall (at or below Va) because you increase the AOA beyond the critical AOA...

So..do the compressor blades (angle) actually change? Are they fixed? How do they "stall"?

-mini

 

[9GClub]

Do the blades actually stall (i.e. is a critical angle of attack exceeded because of the airflow direction) or is there just not enough air getting into the combustion chamber? I always thought the flame that's visible is fuel igniting after a screwy fuel/air ratio caused by insufficient air volume.

I suppose a blade stall would cause such a condition, but I never thought of it that way.

 

[GravityHater]

Mini, I always understood it to be not enough airflow for the speed the compressor blades are already spinning at. In this situation, I can conceptualize a stalled blade.
I too, seek more detailed answers, good question flybzz.

 

[aucfi]

So..do the compressor blades (angle) actually change? Are they fixed? How do they "stall"?

The AOA the compressor blades have is a result of the inlet air velocity and compressor RPM. Think of how your fixed pitch propellers are efficient at only one airspeed. When the airflow is disrupted into the compressor, this airspeed changes and for that given RPM the rotors are at, the blades become inefficient and can "stall".


Compressor can stall for various other reasons. Some are excessive fuel flow caused by abrupt engine acceleration, excessive lean mixture caused by abrupt engine deceleration, contaminated or damaged compressors, damaged turbine components, and/or plain old exceeding the "red line" RPM.



A compressor stall can be best described as an imbalance between inlet velocity and compressor RPM.

 

[mar]

Inlets, diffusers and Bernoulli

I guess what you really need to understand is the importance of the inlet and exactly what's happening in terms of pressure, temperature and speed.

It's true the compressor blades are little airfoils that have an angle of attack, so to speak.

But even before the air reaches the blades it's modified by the inlet.

The engine inlet and the spinner both serve to diffuse the airflow (slow it down, increase the pressure) before it ever reaches the blades. The inlet and spinner also present the airflow to the compressor face for smooth operation...but it has limits.

Like others have mentioned, if the airplane has a high pitch attitude, low airspeed and high power setting, the airflow to the compressor face may actually be turbulent enough to induce a compressor stall.

In other words, the compressor blades are just not getting enough "clean" air to compress and send back into the engine for combustion.

The result is the banging (or backfiring, as some say) of the compressor stall. Actually it's the higher pressure air inside the engine trying to escape (because nature abhors a vacuum) through the FRONT of the engine.

Bad news. Best solution: reduce power, lower pitch and increase airspeed in order to regain a nice smooth airflow back into the engine.

Basically you want smooth, high pressure air shoved up against the compressor face or you're gonna ruin the engine with high EGT.

 

[minitour]

Cool. Thanks for the good info all.

-mini

 

[avbug]

Plenty of people care. But thanks for your opinion. Tell you what. If you're such a tough guy, why don't you email me your name. Just your name, nothing else. But you have to be honest about it. That way, when your airplane gets sold out from underneath you because your boss decided to goto to NetJets or dies, or goes out of business.... I'll remember your name when you apply and come in for an interview. You see, this is a small industry. We all win run into one another someday. If you're man enough to give me your name, I feel sorry for you if you ever think of applying to us or say... Southwest. You see, Southwest is full of ex-Netjets pilots and once a name is put on that blacklist, you're done.

You sound like a SCAB or a potential SCAB to me by making comments about a brother picketing for what he believes in.

So how about it? Got balls?

Now that sounds like the disgruntled netjets pilots we all know and love at Signature's everywhere. Keep up the consistancy!