To sum it up for those who don't understand, simply put, there is more pressure in the combustion chamber (where the fuel is burned) than the compressor (where the intake air is compressed and gains pressure and heat), so the gases are pushed towards the front where there is lower pressure, so the gases are flowing the wrong way.
Kid Mechanic kind of, however it's the angle of incidence to the angle of air flow, much like the leading edge of a airliner wing aerofoil. Example, if the angle of incidence is too steep the incoming air hits the leading edge of the compressor blade too steep, so instead of moving the air to the statior vanes to be slowed down "compressed" there is actuly negative pressure created so the compressor blade can't "bite" into the air so to speak "I'm trying to keep this simple and not a 4,000 word paper aha"
Jack Selby so this angel of incidence is the only probable cause during take off or climb OR one reason could also be that FOD OR pushing the throttle fwd too fast...please explain and thank you
Fayyaz Riyaz yes and No, air temperature has a big affect on turbine engines, as you probably know :) so to further explain what I mean. The compressor blades are at a set angle, this is called the Angel of insandece, it's set to maximise the areofoil affect of the blade, however there is no perfect Angel of incidence unfortunly. So to aid the compressor in acheving maximum performance thorgh it's power band, the engine is fitted with VIGVs or veribal inlet guide vaines. These can move 130°, at low power these in there closed position, facing the leading edge of the compressor blade to maximise the amount of lift generated at the blade, as at low power the compressor struggles to redirect the incoming air. When the power level is increased the VIGVs change angel SLOWLY so there is no sudden change in air pressure and velocity within the inlet of the compressor. If the change is too sudden the change in air pressure hinders the affect of the compressor blades, this causes the pressure to drop quickly and dramatically, so now Imagaine all that compressed air at the back of the compressor no longer being held back by the incoming air from the front of the compressor. That high pressure air can now come backwards though the compressor further slowing it down making the problem even worse, the bang associated with a compressor stall or surge is the highly compressed air comming back out the front of the engine and rapidly expanding, same story with the flames, this is just the combustion products escaping backwores due to there beaing now less resistance pushing them to the back though and out the turbine stages. I hope this helps :)
A compressor stall is just a backfire in a turbofan engine. the same as when you hear a loud bang when a piston engine backfires. Cause - turbulence in the air flow over the compressor blades (in other words a "Stall") in the compressor section causing a reduction in air pressure and consequent imbalance of fuel /air during combustion. This causes excess unburned fuel to be ejected from the combustion chamber and be ignited in the turbine section causing a lot of flame and noise at the back of the engine. (just like in the exhaust pipe on your car) and a great reduction in thrust on that engine. Of course its a much bigger bang! (much bigger engine!). In a Jet engine this could interrupt the combustion cycle and shut down the engine completely (like blowing out a candle so, its called a "flame out?)) necessitating a restart procedure and a change of pants for the pilot. In a high bypass turbo fan, since the combustion cycle is not interrupted, the condition just repeats itself until the pilot takes remedial action to correct the fuel/air imbalance and stop the compressor stall, then generally returns to have the engine inspected for any possible damage. Hope that helps.
Thank you, 30 second read much better than the videos that try to explain. They all mean well, but they take too long to get it out, or over complicate it by giving way too much info.
I would just mention the pressure created by the excess combustion is what caused the ignition in the turbine section, it’s not just excess fuel in the turbine section
That was easy enough to understand. So basically, the engine burps out a flame to the front simply because it has way too much fuel to burn in the combustion chamber, and very little airflow/pressure to push the flame back out the exhaust. That being the case, the way to recover from the situation is to cut off fuel, and the best way to do this is to do it automatically with a sensor-monitored/servo-activated fuel shut off valve that can be overridden by the operator. Thank you for the explanation.
I think that you induce a little confusion when you refer to 'increased pressure' in the combustion section when you mean that the pressure stays roughly the same there and the air flow starts to reverse forward to the compressor section because the pressure there has dropped during to the disruption. If the pressure increases in the combustion section, it would be due to increased temperature due to a disruption of gases being exhausted. That would follow the disruption but would lag somewhat.
Got what he was trying to say after the first preamble -- after the first 3 minutes. Pretty simple -- yet he rambles on duplicating and muddling. Maybe he knows -- but he does not teach in simple terms.
Very interesting! It kind of reminds me of what can happen if you don't lean out the mixture at higher altitude. You have an imbalance in fuel to air density ratio.
Using the diagram explained compression stall in a clear and concise manner. Also for the first, time i had a clear understanding of turbo fan jet engine operational principle. While i may have written this a bit differently, a bit more concisely and differential why the wings and engines angle of attack effect laminar flow inside the compressor section of the jet , KUDOS! JOB WELL DONE. Many thanks.
I was told that it's a reversal of airflow to the front of the engine due to a pressure drop (for whatever reason) in the intake side airflow. Normally the intake pressure is sufficient to prevent a reversal of airflow but an interruption can cause that pressure to drop low enough to allow the airflow to reverse direction until the intake side is stabilized once again. That may be an oversimplification. The part about the fuel still flowing and igniting when that intake disruption happens was new information so thanks.
I've never even been near a jet engine, yet after watching this video just once I've been hired as a senior maintenance technician at over 3 top name airline companies
Step 1. Watch this video. Step 2. Schedule the interview. Step 3. Sleep at a Holiday Inn Express the night before the interview. Step 4. Enjoy your new career!
Thanks for this really good explenation. So just for my understanding, Compressor stall ist most likley to be a pilot error? A Bird strike aside could there be another technical reason for a Compressor stall?
Thank-you for your explanation. I was able to follow the lesson well. Nevertheless, I thank-you all for your comments, which embellished what the instructor was explaining.
Very good explanation. In very simple terms, it is caused due to, not enough pressure created in the compressor to push the air forward. This can be caused due damages, wear and tear of the stator and rotor of the compressor, an external body stuck into the compressor, improper throttling that creates Temperory surge etc.
I'm a proces automation technician, with absolutely no knowledge of jet engines, but in my Profession i'm often confronted to solve safety and control issues. So i'm assuming that a jet engine has some kind of control system. When your control unit compares the compressor aft pressure with the combustion chamber pressure it can take appropriate action to protect the engine, of course with flightsafety in mind (better a destroyed engine than a crashed plane). I'm sure that jet engine engineers have considered something like this but can't be realised?
Great video!! So can you tell us what caused the compressor stall on the Philippines B777 flight from LAX to Manila that during takeoff that had to return of LAX? Let’s say the angle of attack and power settings were ok and no Fod entered the engine. What else could’ve stalled this aircraft?
Why isn't there a automated fuel shutoff device activated by the disrupted airflow in the compressor section or a reversed pressure gradient toward the intake part of engine?
In order for combustion to occur, oxygen and heat and fuel have to be in proper ratios to each other. If you have an excess or not enough fuel or oxygen or heat, then combustion will not happen. It's commonly referred to as the combustion triangle (because of the three things needed and they are connected to each other).
To prevent a compressor stall, inlet guid vanes IGV and or Bleed-air valves are the keys to recover the stall. My question is: what controls the bleed-air valves and IGV angle to open or correct the angle of the compressor blades? it is fascinating topic to discus this theory. Please tell me how those valves open and how those blades to correct their angle of attack properly?
That is a good question.. I know the FADEC or more precise the EECU provides protection against engine surge and flame out during transients, but once it happens I think you have to monitor and correct you power setting...
You keep swapping pressure and velocity and it gets quite confusing. Try writing it down before making the video so you don't keep correcting yourself.
Burning fuel creates a lot of heat which causes the air to expand, too much fuel creates too much temperature - more volume in the same space equals more pressure, if this happens suddenly the higher pressure partially blocks the air exiting the compressor and also may overheat the turbine.
I guess this explains why pilots need to spool up engines at takeoff before going full throttle to avoid compressor stalls. The only thing that confuses me is that if as you said the pressure drops at compressor level and and the exploded fuel and air in the chamber tend to go reverse then why do we still have engines BACK firing? why don't we see FRONT fire? Thanks
The term back fire is a convential piston engine term and refers to the fuel/air mixture igniting inside the combustion portion of the head at the wrong time with the expanding gases going out thru an open intake valve instead of properly exiting thru an exhaust valve. With that, you typically have fire shooting out thru the carburator for a split second instead of out the exhaust pipe. This can be caused by several things, such as misadjusted timing, preignition, etc. So it is actually a front fire, but called a back fire meaning backward or reverse of where it should fire. On a jet engine, it does not have intake valves and exhaust valves and only uses a spark plug (ignitor in a jet engine) to ignite the compressed air/fuel mixture during engine start up. After the jet engine is running, it no longer needs the ignitors unless a restart is needed. When a jet engine stalls, it typically will shoot a flame out the front of the engine for a split second also.
When you talk about ways to fix the stall. You say one part of it is increasing the airflow (by increased airspeed) through the front, to of course get everything spinning faster (and re gain the corresponding pressure for the given fuel flow). But you also mention to decrease the angle of the attack. Are you referring to the airflow that is head-on to the aircraft, hitting the fan blades. Because this is basically the same as increasing airflow, or airspeed.
Um why would anyone design an engine that has a chance of stalling, overheating the EGT, causing a vibration with a bang or several bangs or surges. Pretty sad
Willie Gillie there is no perfect Angel of incidence unfortunly as depending on air speed and pressure, so engineer's try find a good balance, this is difficult due to the constant change in velocity and pressure...thats why jet engines, not turbo fans have VIGVS or variable inlet guide vanes, these change pitch depending on engine power, to redirect the angle of attack to better sute to Angel of insandece at the compressor blade
Anthony Smith This is an extremely fast spinning engine when spooled up to full throttle internal N2 turbines(GE 90) typically spin slightly over 10,000 rpm while the N1 stage can reach 2000 rpm and newer reach even higher which typically is over Mach 1.2 further out toward the ends of the Turbofan blades. These engines have to be tested for contained failure of the turbofan and destruction of the engine. Does this sound like a good design decision to you?
what i don’t get is how can burner pressure increase if it’s not an isentropic process. pressure should be either the same or lower in combustion chamber
how does the pressure increase in combustion chamber? Do you mean it is because the fuel keep going into the area? Or do you mean because more fuel is burn?
Let's say you want to maintain 3000 rpm the amount of fuel and air needed for 3000 rpm are even then you shut the air off or rapidly decreased and you still have the same amount of fuel being injected into the combustion chamber and also burned. your fuel to air ratio is going to be much higher than it should be because the lack of air. Your egt's(exhaust gas temp.) Will then rapidly climb because the air also cools the combustion chamber.
Generally, higher speeds will prevent the back flow of air as it will increase airflow through the engine, thereby increasing the pressure aft of the compressor section.
Fuel flow into the combustor is NOT controlled by the "throttle" - it is continuously and precisely controlled by the electronic engine control system (a complex digital computer) and the fuel metering unit. The ECU receives many sensor signals and is always working to limit speeds, temperatures and pressures in the engine - things that a human could never do with the necessary speed and accuracy.
Dude, please....go back, do your homework, organize your presentation, then come back and try again. Many of us are genuinely interested but at this point, genuinely confused.
'Brilliant' analysis from cosmetics sales; but which logical fallacy did you fail to detect? The lack of care in not turning off notifications, or caring about editing them out, was reflected in the general standard of the presentation. Sloppy.
Too much fuel not enough oxygen equals loss of ignition, the damn thing is flooded, will not produce power and it pops and backfires! A painful over-explanation deserves an equal but painless under-explanation.
If you want a real life example of a Compressor Stall , here is a link to ATC conversion for Delta 1643 on Nov 10, 2017. I caught it cause my wife was supposed to be on the plane. You can hear at 18min 40sec that the pilot report an emergency. And later explains it was a compressor stall : archive-server.liveatc.net/cyul/CYUL-App-Nov-10-2017-2330Z.mp3
Incorrect, this is not how it works. Pressure is not increased in the combustion chamber. There are two different forms of pressure, static and stagnation pressure. Stagnation pressure actually drops in combustion chamber whereas it isn't as straightforward as static, which is always changing. This is why what you see as your EPR or P3 (if you have this displayed most likely not) on your ECAM/ECAS for the compressor exit is in stagnation. What happens in the compressor is it turns the airflow causing incremental increases in pressure through the compressor. Through different spools and variable stator vanes the compressor tries to modulate how this is done to avoid surge in simple text. What a surge is is that there is not enough mass flow for the operating pressure ratio in the compressor causing back flow, caused by tip leakage, FOD, etc,you want to reduce the power or fuel going into the engine so you don't burn out your blades, but your fuel flow doesn't directly more indirectly affect surge. Its all about energy conservation, compressor turbine mapping to have a stable operating point. Anyway I don't believe your explanation is factually correct or your message is really confusing...
This is becoming pretty outdated- I don't know any fairly modern engine that has a centrifugal compressor- not to say that I don't like the older compressors!
BULLSHIT ! Confusion City ! The reason they use the word "STALL" is because it's the same word we use for any wing or blade that experiences a disruption in airflow. In this case we are talking about the blades on the COMPRESSOR , not the whole engine and the turbine too. The blades on the compressor stall because the angle of incidence is too great for the reduced flow/airspeed due to bird strike or whatever caused it. This wing/blade stall can be mitigated by the use of inlet vane guides (IVGs) which can adjust the direction of airflow to reduce the angle of incidence and mitigate the stall.
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To sum it up for those who don't understand, simply put, there is more pressure in the combustion chamber (where the fuel is burned) than the compressor (where the intake air is compressed and gains pressure and heat), so the gases are pushed towards the front where there is lower pressure, so the gases are flowing the wrong way.
Kid Mechanic kind of, however it's the angle of incidence to the angle of air flow, much like the leading edge of a airliner wing aerofoil. Example, if the angle of incidence is too steep the incoming air hits the leading edge of the compressor blade too steep, so instead of moving the air to the statior vanes to be slowed down "compressed" there is actuly negative pressure created so the compressor blade can't "bite" into the air so to speak "I'm trying to keep this simple and not a 4,000 word paper aha"
Jack Selby so this angel of incidence is the only probable cause during take off or climb OR one reason could also be that FOD OR pushing the throttle fwd too fast...please explain and thank you
Fayyaz Riyaz yes and No, air temperature has a big affect on turbine engines, as you probably know :) so to further explain what I mean. The compressor blades are at a set angle, this is called the Angel of insandece, it's set to maximise the areofoil affect of the blade, however there is no perfect Angel of incidence unfortunly. So to aid the compressor in acheving maximum performance thorgh it's power band, the engine is fitted with VIGVs or veribal inlet guide vaines. These can move 130°, at low power these in there closed position, facing the leading edge of the compressor blade to maximise the amount of lift generated at the blade, as at low power the compressor struggles to redirect the incoming air. When the power level is increased the VIGVs change angel SLOWLY so there is no sudden change in air pressure and velocity within the inlet of the compressor. If the change is too sudden the change in air pressure hinders the affect of the compressor blades, this causes the pressure to drop quickly and dramatically, so now Imagaine all that compressed air at the back of the compressor no longer being held back by the incoming air from the front of the compressor. That high pressure air can now come backwards though the compressor further slowing it down making the problem even worse, the bang associated with a compressor stall or surge is the highly compressed air comming back out the front of the engine and rapidly expanding, same story with the flames, this is just the combustion products escaping backwores due to there beaing now less resistance pushing them to the back though and out the turbine stages. I hope this helps :)
Very well said. Note to self. Work on spelling
Aha thankyou, my dyslexia is bad
A compressor stall is just a backfire in a turbofan engine. the same as when you hear a loud bang when a piston engine backfires. Cause - turbulence in the air flow over the compressor blades (in other words a "Stall") in the compressor section causing a reduction in air pressure and consequent imbalance of fuel /air during combustion. This causes excess unburned fuel to be ejected from the combustion chamber and be ignited in the turbine section causing a lot of flame and noise at the back of the engine. (just like in the exhaust pipe on your car) and a great reduction in thrust on that engine. Of course its a much bigger bang! (much bigger engine!). In a Jet engine this could interrupt the combustion cycle and shut down the engine completely (like blowing out a candle so, its called a "flame out?)) necessitating a restart procedure and a change of pants for the pilot. In a high bypass turbo fan, since the combustion cycle is not interrupted, the condition just repeats itself until the pilot takes remedial action to correct the fuel/air imbalance and stop the compressor stall, then generally returns to have the engine inspected for any possible damage. Hope that helps.
lol a change of pants for the pilot
Brilliantly explained!
Thank you, 30 second read much better than the videos that try to explain. They all mean well, but they take too long to get it out, or over complicate it by giving way too much info.
If the guy in the video just said that it would have been understandable.
I would just mention the pressure created by the excess combustion is what caused the ignition in the turbine section, it’s not just excess fuel in the turbine section
Idk why it took me so long to understand compressor stalls. This video cleared it up completely. Thank you!
Thanks! I knew about compressor stall but didn’t think about the surge repercussions. Thanks for explaining!
That was easy enough to understand. So basically, the engine burps out a flame to the front simply because it has way too much fuel to burn in the combustion chamber, and very little airflow/pressure to push the flame back out the exhaust. That being the case, the way to recover from the situation is to cut off fuel, and the best way to do this is to do it automatically with a sensor-monitored/servo-activated fuel shut off valve that can be overridden by the operator. Thank you for the explanation.
ChuddleBuggy: I don’t think the fuel needs be completely cut off.
I think that you induce a little confusion when you refer to 'increased pressure' in the combustion section when you mean that the pressure stays roughly the same there and the air flow starts to reverse forward to the compressor section because the pressure there has dropped during to the disruption. If the pressure increases in the combustion section, it would be due to increased temperature due to a disruption of gases being exhausted. That would follow the disruption but would lag somewhat.
Got what he was trying to say after the first preamble -- after the first 3 minutes. Pretty simple -- yet he rambles on duplicating and muddling. Maybe he knows -- but he does not teach in simple terms.
Knowing something and teaching it are two different things.
3 min concept extended to unprepared 12 min presentation.
This. And the main point ("not enough RPM") being opposite of the actual case, to boot
Very interesting! It kind of reminds me of what can happen if you don't lean out the mixture at higher altitude. You have an imbalance in fuel to air density ratio.
The volume isn't low enough, I can still barely hear it.
Kept checking my phone thinking that beeping was me
😆
Using the diagram explained compression stall in a clear and concise manner. Also for the first, time i had a clear understanding of turbo fan jet engine operational principle.
While i may have written this a bit differently, a bit more concisely and differential why the wings and engines angle of attack effect laminar flow inside the compressor section of the jet , KUDOS! JOB WELL DONE. Many thanks.
Understood completely. Don't have to be a mathematician to work out your rhetoric. Thanks for the video.
Best explanation on the web anyone could understand.
Amazing. Thanks for the feedback!
Thanks for your effort of explaining this concept ,I much appreciate it.
I was told that it's a reversal of airflow to the front of the engine due to a pressure drop (for whatever reason) in the intake side airflow. Normally the intake pressure is sufficient to prevent a reversal of airflow but an interruption can cause that pressure to drop low enough to allow the airflow to reverse direction until the intake side is stabilized once again. That may be an oversimplification. The part about the fuel still flowing and igniting when that intake disruption happens was new information so thanks.
1:45 *me totally not checking my facebook tab*
Made perfect sense.
Difference between me and a box of rocks is the box, but I understood him.
The main takeaway is, if a compression stall happens,...it's because air flow was restricted.............yeah..
Great video👌
This helped a lot, thanks!
I thought the guy was quite understandable actually
Thanks man 👍🏽
So basically this is causing a super rich fuel mixture? Because of the disruption of air flow
Very good and clear explanation. Thanks
I've never even been near a jet engine, yet after watching this video just once I've been hired as a senior maintenance technician at over 3 top name airline companies
Step 1. Watch this video.
Step 2. Schedule the interview.
Step 3. Sleep at a Holiday Inn Express the night before the interview.
Step 4. Enjoy your new career!
Great video but low volume..
Thanks for this really good explenation. So just for my understanding, Compressor stall ist most likley to be a pilot error? A Bird strike aside could there be another technical reason for a Compressor stall?
Thank-you for your explanation. I was able to follow the lesson well. Nevertheless, I thank-you all for your comments, which embellished what the instructor was explaining.
AgentJayZ has a much better analysis with only one static graphic.
How can the Raptor jet move forward in what is almost a hover with a very high angle of attack during an air show?
Now let me translate all this to passenger language: "We are fucked".
Thank you very much!
Very well explained.Thanks a lot
Very good explanation. In very simple terms, it is caused due to, not enough pressure created in the compressor to push the air forward. This can be caused due damages, wear and tear of the stator and rotor of the compressor, an external body stuck into the compressor, improper throttling that creates Temperory surge etc.
I'm a proces automation technician, with absolutely no knowledge of jet engines, but in my Profession i'm often confronted to solve safety and control issues. So i'm assuming that a jet engine has some kind of control system. When your control unit compares the compressor aft pressure with the combustion chamber pressure it can take appropriate action to protect the engine, of course with flightsafety in mind (better a destroyed engine than a crashed plane). I'm sure that jet engine engineers have considered something like this but can't be realised?
OK - so to fix the issue, decrease angle of attack, lower fuel input and increase air speed. But what happens if you only have one engine?
Great video!! So can you tell us what caused the compressor stall on the Philippines B777 flight from LAX to Manila that during takeoff that had to return of LAX? Let’s say the angle of attack and power settings were ok and no Fod entered the engine. What else could’ve stalled this aircraft?
play video again.
Very well explained.
TH-cam!!! How did I get here? And why was I fascinated?
Is that a turbo fan with a radial compressor stage? 👀
So in a compressor stall the engine doesn't completely stops?
Why isn't there a automated fuel shutoff device activated by the disrupted airflow in the compressor section or a reversed pressure gradient toward the intake part of engine?
You the best sir
very clear explanation. thanks a lot
so because of increase in temp in the combustion section the pressure increase?
Minimized introductory air causes over-rich fuel mixture ( momentary overfuelling) and corresponding backfire.
I understood clearly thx very much
In order for combustion to occur, oxygen and heat and fuel have to be in proper ratios to each other. If you have an excess or not enough fuel or oxygen or heat, then combustion will not happen. It's commonly referred to as the combustion triangle (because of the three things needed and they are connected to each other).
To prevent a compressor stall, inlet guid vanes IGV and or Bleed-air valves are the keys to recover the stall. My question is: what controls the bleed-air valves and IGV angle to open or correct the angle of the compressor blades? it is fascinating topic to discus this theory. Please tell me how those valves open and how those blades to correct their angle of attack properly?
What you ask about is properly explained and the mechanics shown on an engine in this video: th-cam.com/video/yaFeO6Jze64/w-d-xo.html
Has high-tech been achieved yet for real time computer control to automatically adjust in the event of compressor stall?
That is a good question.. I know the FADEC or more precise the EECU provides protection against engine surge and flame out during transients, but once it happens I think you have to monitor and correct you power setting...
You keep swapping pressure and velocity and it gets quite confusing. Try writing it down before making the video so you don't keep correcting yourself.
Wonderful video! Very clear and forward i love it, thank you so much. One question though, why does fuel increase the pressure?
Burning fuel creates a lot of heat which causes the air to expand, too much fuel creates too much temperature - more volume in the same space equals more pressure, if this happens suddenly the higher pressure partially blocks the air exiting the compressor and also may overheat the turbine.
is anyone else having a problem with sound?
Yes very low volume, add to this problem with the description of the subject matter
Yes, the uploader.
This is not rocket science fellas. It's a backfire, that's all, just done jet engine style.
I guess this explains why pilots need to spool up engines at takeoff before going full throttle to avoid compressor stalls.
The only thing that confuses me is that if as you said the pressure drops at compressor level and and the exploded fuel and air in the chamber tend to go reverse then why do we still have engines BACK firing? why don't we see FRONT fire?
Thanks
The term back fire is a convential piston engine term and refers to the fuel/air mixture igniting inside the combustion portion of the head at the wrong time with the expanding gases going out thru an open intake valve instead of properly exiting thru an exhaust valve. With that, you typically have fire shooting out thru the carburator for a split second instead of out the exhaust pipe. This can be caused by several things, such as misadjusted timing, preignition, etc. So it is actually a front fire, but called a back fire meaning backward or reverse of where it should fire.
On a jet engine, it does not have intake valves and exhaust valves and only uses a spark plug (ignitor in a jet engine) to ignite the compressed air/fuel mixture during engine start up. After the jet engine is running, it no longer needs the ignitors unless a restart is needed. When a jet engine stalls, it typically will shoot a flame out the front of the engine for a split second also.
Jet farts:
That waz é Power-Phull
When you talk about ways to fix the stall. You say one part of it is increasing the airflow (by increased airspeed) through the front, to of course get everything spinning faster (and re gain the corresponding pressure for the given fuel flow). But you also mention to decrease the angle of the attack. Are you referring to the airflow that is head-on to the aircraft, hitting the fan blades. Because this is basically the same as increasing airflow, or airspeed.
Ahhh just heard you say ‘decrease the angle of attack, IF THATS THE ISSUE’ Makes more sense now
Um why would anyone design an engine that has a chance of stalling, overheating the EGT, causing a vibration with a bang or several bangs or surges. Pretty sad
Willie Gillie there is no perfect Angel of incidence unfortunly as depending on air speed and pressure, so engineer's try find a good balance, this is difficult due to the constant change in velocity and pressure...thats why jet engines, not turbo fans have VIGVS or variable inlet guide vanes, these change pitch depending on engine power, to redirect the angle of attack to better sute to Angel of insandece at the compressor blade
Anthony Smith who me?
Anthony Smith This is an extremely fast spinning engine when spooled up to full throttle internal N2 turbines(GE 90) typically spin slightly over 10,000 rpm while the N1 stage can reach 2000 rpm and newer reach even higher which typically is over Mach 1.2 further out toward the ends of the Turbofan blades. These engines have to be tested for contained failure of the turbofan and destruction of the engine. Does this sound like a good design decision to you?
what i don’t get is how can burner pressure increase if it’s not an isentropic process. pressure should be either the same or lower in combustion chamber
like how does increase fuel flow increase airflow pressure
how does the pressure increase in combustion chamber?
Do you mean it is because the fuel keep going into the area?
Or do you mean because more fuel is burn?
Let's say you want to maintain 3000 rpm the amount of fuel and air needed for 3000 rpm are even then you shut the air off or rapidly decreased and you still have the same amount of fuel being injected into the combustion chamber and also burned. your fuel to air ratio is going to be much higher than it should be because the lack of air. Your egt's(exhaust gas temp.) Will then rapidly climb because the air also cools the combustion chamber.
Very clear explanation, thank you for posting!
Good vid
Can high speed climbs cause a compressor stall?
Generally, higher speeds will prevent the back flow of air as it will increase airflow through the engine, thereby increasing the pressure aft of the compressor section.
Useful explanatory video.
Prolix, but comprehensible.
Ijectornya agak maju pas di masuknya angin dengan minyak tekanan tinggi jadi nyemprot
Would the engine have to do a check after this?
Yes definitely
Very nice Thank you
Fuel flow into the combustor is NOT controlled by the "throttle" - it is continuously and precisely controlled by the electronic engine control system (a complex digital computer) and the fuel metering unit. The ECU receives many sensor signals and is always working to limit speeds, temperatures and pressures in the engine - things that a human could never do with the necessary speed and accuracy.
Paul Avery from NC?
@@richardbryant366 - Not me :)
PAL PR113 brought me here.
Dude, please....go back, do your homework, organize your presentation, then come back and try again. Many of us are genuinely interested but at this point, genuinely confused.
'Brilliant' analysis from cosmetics sales; but which logical fallacy did you fail to detect?
The lack of care in not turning off notifications, or caring about editing them out, was reflected in the general standard of the presentation.
Sloppy.
v helpful n well explained...kudos
You got a Facebook message
Too rich mixture 🤔
Too much fuel not enough oxygen equals loss of ignition, the damn thing is flooded, will not produce power and it pops and backfires! A painful over-explanation deserves an equal but painless under-explanation.
Who's here after swiss001 video?
sound sucks. I have everything at 100% and I can barely hear you.
No. You said it in a way that is confused.
Explanation was pretty clear, I'm surprised at some of the comments
If you want a real life example of a Compressor Stall , here is a link to ATC conversion for Delta 1643 on Nov 10, 2017. I caught it cause my wife was supposed to be on the plane. You can hear at 18min 40sec that the pilot report an emergency. And later explains it was a compressor stall : archive-server.liveatc.net/cyul/CYUL-App-Nov-10-2017-2330Z.mp3
Very good explanation thanks!
Totally incomprehensible. Totally.
Incorrect, this is not how it works. Pressure is not increased in the combustion chamber. There are two different forms of pressure, static and stagnation pressure. Stagnation pressure actually drops in combustion chamber whereas it isn't as straightforward as static, which is always changing. This is why what you see as your EPR or P3 (if you have this displayed most likely not) on your ECAM/ECAS for the compressor exit is in stagnation. What happens in the compressor is it turns the airflow causing incremental increases in pressure through the compressor. Through different spools and variable stator vanes the compressor tries to modulate how this is done to avoid surge in simple text. What a surge is is that there is not enough mass flow for the operating pressure ratio in the compressor causing back flow, caused by tip leakage, FOD, etc,you want to reduce the power or fuel going into the engine so you don't burn out your blades, but your fuel flow doesn't directly more indirectly affect surge. Its all about energy conservation, compressor turbine mapping to have a stable operating point. Anyway I don't believe your explanation is factually correct or your message is really confusing...
This is becoming pretty outdated- I don't know any fairly modern engine that has a centrifugal compressor- not to say that I don't like the older compressors!
Good but very very slow talk, please speed it up and cut out the unnecessary talk.
BULLSHIT ! Confusion City ! The reason they use the word "STALL" is because it's the same word we use for any wing or blade that experiences a disruption in airflow. In this case we are talking about the blades on the COMPRESSOR , not the whole engine and the turbine too. The blades on the compressor stall because the angle of incidence is too great for the reduced flow/airspeed due to bird strike or whatever caused it. This wing/blade stall can be mitigated by the use of inlet vane guides (IVGs) which can adjust the direction of airflow to reduce the angle of incidence and mitigate the stall.
I think you confused yourself trying to over explain it. Cut it down to 2 minutes
not the best explanation.
So, give me yours.
I need a poo. I can feel it Butting my undies all this talk about air backing up has done it
You need to lear this subject better before you try to teach it - you have no idea !
Soooo.... reduce fuel and slightly pitch forward