Is the bleed air passengers breathe tapped from the engines before or after it comes in contact with fuel?...












9














Passengers are often surprised to hear that the air they breathe comes from inside the engines.




  • This sounds unhealthy. Can you explain, why it is not ?


  • Is bleed air tapped (for cabin pressurization) before or after it comes in contact with fuel inside turbofan engines on passenger airliners ?


  • And what is the reason for either choice ?


  • Specifically where is the location in this diagram ? (diagrams in answers would be very welcome)



scope: This question is about the air breathed by humans inside the plane. Q11917 is about de-icing. Neither the question nor the answers in Q11917 deal with the aspect of whether the air would be safely breathable for passengers and crew. This aspect is very well dealt with in the comments and answers below. As such, these questions should remain separate.



img










share|improve this question




















  • 9




    Think about this for a second - if it comes after the air is in contact with the fuel and it's being used for cabin pressurization, that would mean you'd be building up a fuel-air mixture in the cabin - which would be toxic in the best scenario, and explosive in the worst.
    – FKEinternet
    Dec 10 at 1:04










  • I'm asking because cabin air sometimes smells of kerosene.
    – summerrain
    Dec 10 at 9:16






  • 3




    I'd guess cabin air smelling of kerosene has to do with standing on the ground before takeoff amid kerosene being used --- by other planes, by own idling engines, wafting from just-released fuel truck nozzle, ... --- so whatever outside air is taken in must carry the smell (via the open doors everyone just entered through, if from a staircase; or any air intake point).
    – user3445853
    Dec 10 at 14:06






  • 2




    Possible duplicate of Why is bleed air taken from some stage of the compressor used for de-icing? Why not e.g. exhaust gas?
    – fooot
    Dec 12 at 20:15






  • 1




    @fooot I don't see how it's a duplicate of that. Cabin air isn't taken from the exhaust because the passengers need oxygen; it isn't taken after fuel injection because the passengers need a cabin full of no jet fuel.
    – David Richerby
    Dec 13 at 12:22
















9














Passengers are often surprised to hear that the air they breathe comes from inside the engines.




  • This sounds unhealthy. Can you explain, why it is not ?


  • Is bleed air tapped (for cabin pressurization) before or after it comes in contact with fuel inside turbofan engines on passenger airliners ?


  • And what is the reason for either choice ?


  • Specifically where is the location in this diagram ? (diagrams in answers would be very welcome)



scope: This question is about the air breathed by humans inside the plane. Q11917 is about de-icing. Neither the question nor the answers in Q11917 deal with the aspect of whether the air would be safely breathable for passengers and crew. This aspect is very well dealt with in the comments and answers below. As such, these questions should remain separate.



img










share|improve this question




















  • 9




    Think about this for a second - if it comes after the air is in contact with the fuel and it's being used for cabin pressurization, that would mean you'd be building up a fuel-air mixture in the cabin - which would be toxic in the best scenario, and explosive in the worst.
    – FKEinternet
    Dec 10 at 1:04










  • I'm asking because cabin air sometimes smells of kerosene.
    – summerrain
    Dec 10 at 9:16






  • 3




    I'd guess cabin air smelling of kerosene has to do with standing on the ground before takeoff amid kerosene being used --- by other planes, by own idling engines, wafting from just-released fuel truck nozzle, ... --- so whatever outside air is taken in must carry the smell (via the open doors everyone just entered through, if from a staircase; or any air intake point).
    – user3445853
    Dec 10 at 14:06






  • 2




    Possible duplicate of Why is bleed air taken from some stage of the compressor used for de-icing? Why not e.g. exhaust gas?
    – fooot
    Dec 12 at 20:15






  • 1




    @fooot I don't see how it's a duplicate of that. Cabin air isn't taken from the exhaust because the passengers need oxygen; it isn't taken after fuel injection because the passengers need a cabin full of no jet fuel.
    – David Richerby
    Dec 13 at 12:22














9












9








9


1





Passengers are often surprised to hear that the air they breathe comes from inside the engines.




  • This sounds unhealthy. Can you explain, why it is not ?


  • Is bleed air tapped (for cabin pressurization) before or after it comes in contact with fuel inside turbofan engines on passenger airliners ?


  • And what is the reason for either choice ?


  • Specifically where is the location in this diagram ? (diagrams in answers would be very welcome)



scope: This question is about the air breathed by humans inside the plane. Q11917 is about de-icing. Neither the question nor the answers in Q11917 deal with the aspect of whether the air would be safely breathable for passengers and crew. This aspect is very well dealt with in the comments and answers below. As such, these questions should remain separate.



img










share|improve this question















Passengers are often surprised to hear that the air they breathe comes from inside the engines.




  • This sounds unhealthy. Can you explain, why it is not ?


  • Is bleed air tapped (for cabin pressurization) before or after it comes in contact with fuel inside turbofan engines on passenger airliners ?


  • And what is the reason for either choice ?


  • Specifically where is the location in this diagram ? (diagrams in answers would be very welcome)



scope: This question is about the air breathed by humans inside the plane. Q11917 is about de-icing. Neither the question nor the answers in Q11917 deal with the aspect of whether the air would be safely breathable for passengers and crew. This aspect is very well dealt with in the comments and answers below. As such, these questions should remain separate.



img







airliner engine turbofan engine-design bleed-air






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Dec 13 at 12:55

























asked Dec 9 at 18:16









summerrain

1,0301520




1,0301520








  • 9




    Think about this for a second - if it comes after the air is in contact with the fuel and it's being used for cabin pressurization, that would mean you'd be building up a fuel-air mixture in the cabin - which would be toxic in the best scenario, and explosive in the worst.
    – FKEinternet
    Dec 10 at 1:04










  • I'm asking because cabin air sometimes smells of kerosene.
    – summerrain
    Dec 10 at 9:16






  • 3




    I'd guess cabin air smelling of kerosene has to do with standing on the ground before takeoff amid kerosene being used --- by other planes, by own idling engines, wafting from just-released fuel truck nozzle, ... --- so whatever outside air is taken in must carry the smell (via the open doors everyone just entered through, if from a staircase; or any air intake point).
    – user3445853
    Dec 10 at 14:06






  • 2




    Possible duplicate of Why is bleed air taken from some stage of the compressor used for de-icing? Why not e.g. exhaust gas?
    – fooot
    Dec 12 at 20:15






  • 1




    @fooot I don't see how it's a duplicate of that. Cabin air isn't taken from the exhaust because the passengers need oxygen; it isn't taken after fuel injection because the passengers need a cabin full of no jet fuel.
    – David Richerby
    Dec 13 at 12:22














  • 9




    Think about this for a second - if it comes after the air is in contact with the fuel and it's being used for cabin pressurization, that would mean you'd be building up a fuel-air mixture in the cabin - which would be toxic in the best scenario, and explosive in the worst.
    – FKEinternet
    Dec 10 at 1:04










  • I'm asking because cabin air sometimes smells of kerosene.
    – summerrain
    Dec 10 at 9:16






  • 3




    I'd guess cabin air smelling of kerosene has to do with standing on the ground before takeoff amid kerosene being used --- by other planes, by own idling engines, wafting from just-released fuel truck nozzle, ... --- so whatever outside air is taken in must carry the smell (via the open doors everyone just entered through, if from a staircase; or any air intake point).
    – user3445853
    Dec 10 at 14:06






  • 2




    Possible duplicate of Why is bleed air taken from some stage of the compressor used for de-icing? Why not e.g. exhaust gas?
    – fooot
    Dec 12 at 20:15






  • 1




    @fooot I don't see how it's a duplicate of that. Cabin air isn't taken from the exhaust because the passengers need oxygen; it isn't taken after fuel injection because the passengers need a cabin full of no jet fuel.
    – David Richerby
    Dec 13 at 12:22








9




9




Think about this for a second - if it comes after the air is in contact with the fuel and it's being used for cabin pressurization, that would mean you'd be building up a fuel-air mixture in the cabin - which would be toxic in the best scenario, and explosive in the worst.
– FKEinternet
Dec 10 at 1:04




Think about this for a second - if it comes after the air is in contact with the fuel and it's being used for cabin pressurization, that would mean you'd be building up a fuel-air mixture in the cabin - which would be toxic in the best scenario, and explosive in the worst.
– FKEinternet
Dec 10 at 1:04












I'm asking because cabin air sometimes smells of kerosene.
– summerrain
Dec 10 at 9:16




I'm asking because cabin air sometimes smells of kerosene.
– summerrain
Dec 10 at 9:16




3




3




I'd guess cabin air smelling of kerosene has to do with standing on the ground before takeoff amid kerosene being used --- by other planes, by own idling engines, wafting from just-released fuel truck nozzle, ... --- so whatever outside air is taken in must carry the smell (via the open doors everyone just entered through, if from a staircase; or any air intake point).
– user3445853
Dec 10 at 14:06




I'd guess cabin air smelling of kerosene has to do with standing on the ground before takeoff amid kerosene being used --- by other planes, by own idling engines, wafting from just-released fuel truck nozzle, ... --- so whatever outside air is taken in must carry the smell (via the open doors everyone just entered through, if from a staircase; or any air intake point).
– user3445853
Dec 10 at 14:06




2




2




Possible duplicate of Why is bleed air taken from some stage of the compressor used for de-icing? Why not e.g. exhaust gas?
– fooot
Dec 12 at 20:15




Possible duplicate of Why is bleed air taken from some stage of the compressor used for de-icing? Why not e.g. exhaust gas?
– fooot
Dec 12 at 20:15




1




1




@fooot I don't see how it's a duplicate of that. Cabin air isn't taken from the exhaust because the passengers need oxygen; it isn't taken after fuel injection because the passengers need a cabin full of no jet fuel.
– David Richerby
Dec 13 at 12:22




@fooot I don't see how it's a duplicate of that. Cabin air isn't taken from the exhaust because the passengers need oxygen; it isn't taken after fuel injection because the passengers need a cabin full of no jet fuel.
– David Richerby
Dec 13 at 12:22










3 Answers
3






active

oldest

votes


















28














The bleed will be tapped from one or two of the 3rd, 4th, 5th or 6th High Pressure Compressor stages. Usually there are two bleed ports. The highest pressure port will supply really hot air for things like anti-icing. The lower pressure port farther upstream will supply air for air conditioning/pressurization and other pneumatics. Some systems combine the two ports into one system and draw from the low pressure or high pressure one as required.



The air has to come from the compressor, not after combustion, mainly because it needs to be clean ambient air free of kerosene combustion byproducts, and it's plenty hot enough anyway and taking it from the turbine would be way too hot. The discharge in the last stages of the HP compressor can be upwards of 700-800F at takeoff thrust.



If the aircraft uses a high temperature "evaporative" anti-icing system, it will tap air from hotter stages of the compressor than if there is a non-evaporative system (Evaporative = anti-iced skin temperatures above the boiling point of water. The leading edge will be over 100 C, like the surface of a steam iron.)



Even if it is taking "clean" air, the bleed flow will have all sorts of charred bits of things from the atmosphere in it; pollen, bits of bugs, that collect and get everything dirty in the ducting and components (at lower altitudes). Combusted air would be ten times worse, not to mention the carbon monoxide poisoning the passengers and being way too hot to be usable in the first place.






share|improve this answer



















  • 1




    7th stage bleed is also possible on some engines.
    – Daniel Kiracofe
    Dec 9 at 20:13






  • 6




    Anti-deicing sounds like a terrorist plot :-0
    – TonyK
    Dec 9 at 22:59










  • A secondary reason for multiple bleed ports is to keep the compressor stable. Unlike turbines, compressors are potentially unstable devices, and the overall flow conditions need to be controlled to avoid stall or surge. The bleed ports are in effect part of that control system.
    – alephzero
    Dec 9 at 23:35






  • 1




    "not to mention the carbon monoxide poisoning the passengers" let's not quibble over small details :-)
    – summerrain
    Dec 10 at 5:55






  • 1




    @DevSolar "Clean" from the perspective of a massive jet engine differs quite a bit from "clean" from the perspective of our fragile little human lungs. Even if the combustion is almost perfectly complete, the sheer amount going on would quickly bring ambient CO to lethal concentrations.
    – forest
    Dec 10 at 10:10





















2














To add to what John K already posted, cooling requirements prevent any bleed air being taken in the combustor and high pressure turbine sections. In these sections, thin film cooling is preformed where a small amount of air is injected around the surfaces to prevent the hot combustion products from touching them. Even if the bleed air was being taken for a non-human contact purpose such as active flow control, the air is simply too hot to handle at this point.






share|improve this answer





























    2














    I have found a diagram showing the location where the bleed air is tapped (red arrow).



    As can be seen in the image, the location is upstream of the combustion chambers, which means that bleed air is tapped before it comes into contact with fuel:



    img






    share|improve this answer





















      Your Answer





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      3 Answers
      3






      active

      oldest

      votes








      3 Answers
      3






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes









      28














      The bleed will be tapped from one or two of the 3rd, 4th, 5th or 6th High Pressure Compressor stages. Usually there are two bleed ports. The highest pressure port will supply really hot air for things like anti-icing. The lower pressure port farther upstream will supply air for air conditioning/pressurization and other pneumatics. Some systems combine the two ports into one system and draw from the low pressure or high pressure one as required.



      The air has to come from the compressor, not after combustion, mainly because it needs to be clean ambient air free of kerosene combustion byproducts, and it's plenty hot enough anyway and taking it from the turbine would be way too hot. The discharge in the last stages of the HP compressor can be upwards of 700-800F at takeoff thrust.



      If the aircraft uses a high temperature "evaporative" anti-icing system, it will tap air from hotter stages of the compressor than if there is a non-evaporative system (Evaporative = anti-iced skin temperatures above the boiling point of water. The leading edge will be over 100 C, like the surface of a steam iron.)



      Even if it is taking "clean" air, the bleed flow will have all sorts of charred bits of things from the atmosphere in it; pollen, bits of bugs, that collect and get everything dirty in the ducting and components (at lower altitudes). Combusted air would be ten times worse, not to mention the carbon monoxide poisoning the passengers and being way too hot to be usable in the first place.






      share|improve this answer



















      • 1




        7th stage bleed is also possible on some engines.
        – Daniel Kiracofe
        Dec 9 at 20:13






      • 6




        Anti-deicing sounds like a terrorist plot :-0
        – TonyK
        Dec 9 at 22:59










      • A secondary reason for multiple bleed ports is to keep the compressor stable. Unlike turbines, compressors are potentially unstable devices, and the overall flow conditions need to be controlled to avoid stall or surge. The bleed ports are in effect part of that control system.
        – alephzero
        Dec 9 at 23:35






      • 1




        "not to mention the carbon monoxide poisoning the passengers" let's not quibble over small details :-)
        – summerrain
        Dec 10 at 5:55






      • 1




        @DevSolar "Clean" from the perspective of a massive jet engine differs quite a bit from "clean" from the perspective of our fragile little human lungs. Even if the combustion is almost perfectly complete, the sheer amount going on would quickly bring ambient CO to lethal concentrations.
        – forest
        Dec 10 at 10:10


















      28














      The bleed will be tapped from one or two of the 3rd, 4th, 5th or 6th High Pressure Compressor stages. Usually there are two bleed ports. The highest pressure port will supply really hot air for things like anti-icing. The lower pressure port farther upstream will supply air for air conditioning/pressurization and other pneumatics. Some systems combine the two ports into one system and draw from the low pressure or high pressure one as required.



      The air has to come from the compressor, not after combustion, mainly because it needs to be clean ambient air free of kerosene combustion byproducts, and it's plenty hot enough anyway and taking it from the turbine would be way too hot. The discharge in the last stages of the HP compressor can be upwards of 700-800F at takeoff thrust.



      If the aircraft uses a high temperature "evaporative" anti-icing system, it will tap air from hotter stages of the compressor than if there is a non-evaporative system (Evaporative = anti-iced skin temperatures above the boiling point of water. The leading edge will be over 100 C, like the surface of a steam iron.)



      Even if it is taking "clean" air, the bleed flow will have all sorts of charred bits of things from the atmosphere in it; pollen, bits of bugs, that collect and get everything dirty in the ducting and components (at lower altitudes). Combusted air would be ten times worse, not to mention the carbon monoxide poisoning the passengers and being way too hot to be usable in the first place.






      share|improve this answer



















      • 1




        7th stage bleed is also possible on some engines.
        – Daniel Kiracofe
        Dec 9 at 20:13






      • 6




        Anti-deicing sounds like a terrorist plot :-0
        – TonyK
        Dec 9 at 22:59










      • A secondary reason for multiple bleed ports is to keep the compressor stable. Unlike turbines, compressors are potentially unstable devices, and the overall flow conditions need to be controlled to avoid stall or surge. The bleed ports are in effect part of that control system.
        – alephzero
        Dec 9 at 23:35






      • 1




        "not to mention the carbon monoxide poisoning the passengers" let's not quibble over small details :-)
        – summerrain
        Dec 10 at 5:55






      • 1




        @DevSolar "Clean" from the perspective of a massive jet engine differs quite a bit from "clean" from the perspective of our fragile little human lungs. Even if the combustion is almost perfectly complete, the sheer amount going on would quickly bring ambient CO to lethal concentrations.
        – forest
        Dec 10 at 10:10
















      28












      28








      28






      The bleed will be tapped from one or two of the 3rd, 4th, 5th or 6th High Pressure Compressor stages. Usually there are two bleed ports. The highest pressure port will supply really hot air for things like anti-icing. The lower pressure port farther upstream will supply air for air conditioning/pressurization and other pneumatics. Some systems combine the two ports into one system and draw from the low pressure or high pressure one as required.



      The air has to come from the compressor, not after combustion, mainly because it needs to be clean ambient air free of kerosene combustion byproducts, and it's plenty hot enough anyway and taking it from the turbine would be way too hot. The discharge in the last stages of the HP compressor can be upwards of 700-800F at takeoff thrust.



      If the aircraft uses a high temperature "evaporative" anti-icing system, it will tap air from hotter stages of the compressor than if there is a non-evaporative system (Evaporative = anti-iced skin temperatures above the boiling point of water. The leading edge will be over 100 C, like the surface of a steam iron.)



      Even if it is taking "clean" air, the bleed flow will have all sorts of charred bits of things from the atmosphere in it; pollen, bits of bugs, that collect and get everything dirty in the ducting and components (at lower altitudes). Combusted air would be ten times worse, not to mention the carbon monoxide poisoning the passengers and being way too hot to be usable in the first place.






      share|improve this answer














      The bleed will be tapped from one or two of the 3rd, 4th, 5th or 6th High Pressure Compressor stages. Usually there are two bleed ports. The highest pressure port will supply really hot air for things like anti-icing. The lower pressure port farther upstream will supply air for air conditioning/pressurization and other pneumatics. Some systems combine the two ports into one system and draw from the low pressure or high pressure one as required.



      The air has to come from the compressor, not after combustion, mainly because it needs to be clean ambient air free of kerosene combustion byproducts, and it's plenty hot enough anyway and taking it from the turbine would be way too hot. The discharge in the last stages of the HP compressor can be upwards of 700-800F at takeoff thrust.



      If the aircraft uses a high temperature "evaporative" anti-icing system, it will tap air from hotter stages of the compressor than if there is a non-evaporative system (Evaporative = anti-iced skin temperatures above the boiling point of water. The leading edge will be over 100 C, like the surface of a steam iron.)



      Even if it is taking "clean" air, the bleed flow will have all sorts of charred bits of things from the atmosphere in it; pollen, bits of bugs, that collect and get everything dirty in the ducting and components (at lower altitudes). Combusted air would be ten times worse, not to mention the carbon monoxide poisoning the passengers and being way too hot to be usable in the first place.







      share|improve this answer














      share|improve this answer



      share|improve this answer








      edited Dec 10 at 3:36

























      answered Dec 9 at 19:00









      John K

      13.2k11442




      13.2k11442








      • 1




        7th stage bleed is also possible on some engines.
        – Daniel Kiracofe
        Dec 9 at 20:13






      • 6




        Anti-deicing sounds like a terrorist plot :-0
        – TonyK
        Dec 9 at 22:59










      • A secondary reason for multiple bleed ports is to keep the compressor stable. Unlike turbines, compressors are potentially unstable devices, and the overall flow conditions need to be controlled to avoid stall or surge. The bleed ports are in effect part of that control system.
        – alephzero
        Dec 9 at 23:35






      • 1




        "not to mention the carbon monoxide poisoning the passengers" let's not quibble over small details :-)
        – summerrain
        Dec 10 at 5:55






      • 1




        @DevSolar "Clean" from the perspective of a massive jet engine differs quite a bit from "clean" from the perspective of our fragile little human lungs. Even if the combustion is almost perfectly complete, the sheer amount going on would quickly bring ambient CO to lethal concentrations.
        – forest
        Dec 10 at 10:10
















      • 1




        7th stage bleed is also possible on some engines.
        – Daniel Kiracofe
        Dec 9 at 20:13






      • 6




        Anti-deicing sounds like a terrorist plot :-0
        – TonyK
        Dec 9 at 22:59










      • A secondary reason for multiple bleed ports is to keep the compressor stable. Unlike turbines, compressors are potentially unstable devices, and the overall flow conditions need to be controlled to avoid stall or surge. The bleed ports are in effect part of that control system.
        – alephzero
        Dec 9 at 23:35






      • 1




        "not to mention the carbon monoxide poisoning the passengers" let's not quibble over small details :-)
        – summerrain
        Dec 10 at 5:55






      • 1




        @DevSolar "Clean" from the perspective of a massive jet engine differs quite a bit from "clean" from the perspective of our fragile little human lungs. Even if the combustion is almost perfectly complete, the sheer amount going on would quickly bring ambient CO to lethal concentrations.
        – forest
        Dec 10 at 10:10










      1




      1




      7th stage bleed is also possible on some engines.
      – Daniel Kiracofe
      Dec 9 at 20:13




      7th stage bleed is also possible on some engines.
      – Daniel Kiracofe
      Dec 9 at 20:13




      6




      6




      Anti-deicing sounds like a terrorist plot :-0
      – TonyK
      Dec 9 at 22:59




      Anti-deicing sounds like a terrorist plot :-0
      – TonyK
      Dec 9 at 22:59












      A secondary reason for multiple bleed ports is to keep the compressor stable. Unlike turbines, compressors are potentially unstable devices, and the overall flow conditions need to be controlled to avoid stall or surge. The bleed ports are in effect part of that control system.
      – alephzero
      Dec 9 at 23:35




      A secondary reason for multiple bleed ports is to keep the compressor stable. Unlike turbines, compressors are potentially unstable devices, and the overall flow conditions need to be controlled to avoid stall or surge. The bleed ports are in effect part of that control system.
      – alephzero
      Dec 9 at 23:35




      1




      1




      "not to mention the carbon monoxide poisoning the passengers" let's not quibble over small details :-)
      – summerrain
      Dec 10 at 5:55




      "not to mention the carbon monoxide poisoning the passengers" let's not quibble over small details :-)
      – summerrain
      Dec 10 at 5:55




      1




      1




      @DevSolar "Clean" from the perspective of a massive jet engine differs quite a bit from "clean" from the perspective of our fragile little human lungs. Even if the combustion is almost perfectly complete, the sheer amount going on would quickly bring ambient CO to lethal concentrations.
      – forest
      Dec 10 at 10:10






      @DevSolar "Clean" from the perspective of a massive jet engine differs quite a bit from "clean" from the perspective of our fragile little human lungs. Even if the combustion is almost perfectly complete, the sheer amount going on would quickly bring ambient CO to lethal concentrations.
      – forest
      Dec 10 at 10:10













      2














      To add to what John K already posted, cooling requirements prevent any bleed air being taken in the combustor and high pressure turbine sections. In these sections, thin film cooling is preformed where a small amount of air is injected around the surfaces to prevent the hot combustion products from touching them. Even if the bleed air was being taken for a non-human contact purpose such as active flow control, the air is simply too hot to handle at this point.






      share|improve this answer


























        2














        To add to what John K already posted, cooling requirements prevent any bleed air being taken in the combustor and high pressure turbine sections. In these sections, thin film cooling is preformed where a small amount of air is injected around the surfaces to prevent the hot combustion products from touching them. Even if the bleed air was being taken for a non-human contact purpose such as active flow control, the air is simply too hot to handle at this point.






        share|improve this answer
























          2












          2








          2






          To add to what John K already posted, cooling requirements prevent any bleed air being taken in the combustor and high pressure turbine sections. In these sections, thin film cooling is preformed where a small amount of air is injected around the surfaces to prevent the hot combustion products from touching them. Even if the bleed air was being taken for a non-human contact purpose such as active flow control, the air is simply too hot to handle at this point.






          share|improve this answer












          To add to what John K already posted, cooling requirements prevent any bleed air being taken in the combustor and high pressure turbine sections. In these sections, thin film cooling is preformed where a small amount of air is injected around the surfaces to prevent the hot combustion products from touching them. Even if the bleed air was being taken for a non-human contact purpose such as active flow control, the air is simply too hot to handle at this point.







          share|improve this answer












          share|improve this answer



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          answered Dec 10 at 7:19









          XRF

          2455




          2455























              2














              I have found a diagram showing the location where the bleed air is tapped (red arrow).



              As can be seen in the image, the location is upstream of the combustion chambers, which means that bleed air is tapped before it comes into contact with fuel:



              img






              share|improve this answer


























                2














                I have found a diagram showing the location where the bleed air is tapped (red arrow).



                As can be seen in the image, the location is upstream of the combustion chambers, which means that bleed air is tapped before it comes into contact with fuel:



                img






                share|improve this answer
























                  2












                  2








                  2






                  I have found a diagram showing the location where the bleed air is tapped (red arrow).



                  As can be seen in the image, the location is upstream of the combustion chambers, which means that bleed air is tapped before it comes into contact with fuel:



                  img






                  share|improve this answer












                  I have found a diagram showing the location where the bleed air is tapped (red arrow).



                  As can be seen in the image, the location is upstream of the combustion chambers, which means that bleed air is tapped before it comes into contact with fuel:



                  img







                  share|improve this answer












                  share|improve this answer



                  share|improve this answer










                  answered Dec 12 at 19:25









                  summerrain

                  1,0301520




                  1,0301520






























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