Why would a jet engine that runs at temps excess of 2000°C burn when it crashes?












3












$begingroup$


Airline engines are designed to work at very high temperatures. Yet, when a plane crashes they're burnt (see below). Is it something in their design?



enter image description here

(bostonherald.com)










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  • 2




    $begingroup$
    The engine in the photograph is not melted.
    $endgroup$
    – Michael Hall
    3 hours ago










  • $begingroup$
    @MichaelHall: That's on me, I've fixed it. OP originally wrote burnt. Although judging by the LP section, it did melt.
    $endgroup$
    – ymb1
    2 hours ago
















3












$begingroup$


Airline engines are designed to work at very high temperatures. Yet, when a plane crashes they're burnt (see below). Is it something in their design?



enter image description here

(bostonherald.com)










share|improve this question











$endgroup$








  • 2




    $begingroup$
    The engine in the photograph is not melted.
    $endgroup$
    – Michael Hall
    3 hours ago










  • $begingroup$
    @MichaelHall: That's on me, I've fixed it. OP originally wrote burnt. Although judging by the LP section, it did melt.
    $endgroup$
    – ymb1
    2 hours ago














3












3








3





$begingroup$


Airline engines are designed to work at very high temperatures. Yet, when a plane crashes they're burnt (see below). Is it something in their design?



enter image description here

(bostonherald.com)










share|improve this question











$endgroup$




Airline engines are designed to work at very high temperatures. Yet, when a plane crashes they're burnt (see below). Is it something in their design?



enter image description here

(bostonherald.com)







jet-engine accidents aerospace-materials






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited 2 hours ago









ymb1

67k7212355




67k7212355










asked 3 hours ago









RegmiRegmi

1636




1636








  • 2




    $begingroup$
    The engine in the photograph is not melted.
    $endgroup$
    – Michael Hall
    3 hours ago










  • $begingroup$
    @MichaelHall: That's on me, I've fixed it. OP originally wrote burnt. Although judging by the LP section, it did melt.
    $endgroup$
    – ymb1
    2 hours ago














  • 2




    $begingroup$
    The engine in the photograph is not melted.
    $endgroup$
    – Michael Hall
    3 hours ago










  • $begingroup$
    @MichaelHall: That's on me, I've fixed it. OP originally wrote burnt. Although judging by the LP section, it did melt.
    $endgroup$
    – ymb1
    2 hours ago








2




2




$begingroup$
The engine in the photograph is not melted.
$endgroup$
– Michael Hall
3 hours ago




$begingroup$
The engine in the photograph is not melted.
$endgroup$
– Michael Hall
3 hours ago












$begingroup$
@MichaelHall: That's on me, I've fixed it. OP originally wrote burnt. Although judging by the LP section, it did melt.
$endgroup$
– ymb1
2 hours ago




$begingroup$
@MichaelHall: That's on me, I've fixed it. OP originally wrote burnt. Although judging by the LP section, it did melt.
$endgroup$
– ymb1
2 hours ago










2 Answers
2






active

oldest

votes


















12












$begingroup$

How The Jet Engine Works:




Inside the typical commercial jet engine, the fuel burns in the combustion chamber at up to 2000 degrees Celsius. The temperature at which metals in this part of the engine start to melt is 1300 degrees Celsius, so advanced cooling techniques must be used.




You can read more about some of those cooling mechanisms in How are temperature differences handled in a jet engine?



See also, How do you stop a jet engine melting?:




Neil - The normal melting point of the nickel blade alloys that we use in the turbine is typically about 12-1400 degrees. But what you do, and this is the clever bit, is you actually cool these blades. You have internal cooling passages, which effectively has air that flows through and it's about 7-800 degrees. And this cooling air then exits from small little minute holes that have been drilled on the surface of the blade and this air then forms a kind of a film on the surface of the blade, and this technology is typically called a 'film cooling.'



What you also do - you coat these blades and typically use something called a thermal barrier coating. The thermal barrier coating, effectively, is ceramic, typically about quarter of a millimeter in thickness, but they have got very, very low thermal conductivity. So, effectively, even though the gas stream is at a much higher air temperature, the effective metal that exists beneath the thermal barrier coating is much colder, and you get thermal grade of the order of about 100 degrees C between the hot and the cold surface. So all of this put together - this whole cooling technology effectively helps to keep the blade below its melting temperature.




The engine is designed to manage the intense heat in a controlled way, by restricting it to certain components, injecting cool air around the hot parts, and choosing different materials for different parts of the engine. If the engine is severely damaged, doused in jet fuel, and set on fire, none of those mechanisms function; the entire engine (or whatever is left of it), as opposed to just the portions intended to manage heat, will be hot, and none of the cooling mechanisms will be working.






share|improve this answer











$endgroup$





















    6












    $begingroup$

    Peters answer to this question has a nice chart that shows internal jet engine temps:



    enter image description here



    You can see that the temps are highest by a fairly large factor in the combustion chamber. This means that only the combustion chamber needs to be able to withstand those temperatures. To save weight and often use less expensive and less exotic materials the rest of the engine may be made out of materials that don't need to withstand such high temps. As such in an accident where jet fuel may be dispersed in an uncontrolled way and burn with as much oxygen as it can get its easy to scorch engine parts and anything else around.



    It also is in part a question of time. The ability to withstand heat varies with time. In a crash of a fairly fueled aircraft that may burn uncontrolled for a long time you are likely to find scorched parts like this. Where as a plane that runs its tanks try and crashes in a field may not see the same fire marks. However if the plane hits the ground with enough force the heat generated from the impact can also lead to markings like this.






    share|improve this answer











    $endgroup$









    • 4




      $begingroup$
      I'd like to add that there is no point of having a crashed engine survive the crash, +1.
      $endgroup$
      – ymb1
      3 hours ago











    Your Answer





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    2 Answers
    2






    active

    oldest

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    2 Answers
    2






    active

    oldest

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    active

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    active

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    12












    $begingroup$

    How The Jet Engine Works:




    Inside the typical commercial jet engine, the fuel burns in the combustion chamber at up to 2000 degrees Celsius. The temperature at which metals in this part of the engine start to melt is 1300 degrees Celsius, so advanced cooling techniques must be used.




    You can read more about some of those cooling mechanisms in How are temperature differences handled in a jet engine?



    See also, How do you stop a jet engine melting?:




    Neil - The normal melting point of the nickel blade alloys that we use in the turbine is typically about 12-1400 degrees. But what you do, and this is the clever bit, is you actually cool these blades. You have internal cooling passages, which effectively has air that flows through and it's about 7-800 degrees. And this cooling air then exits from small little minute holes that have been drilled on the surface of the blade and this air then forms a kind of a film on the surface of the blade, and this technology is typically called a 'film cooling.'



    What you also do - you coat these blades and typically use something called a thermal barrier coating. The thermal barrier coating, effectively, is ceramic, typically about quarter of a millimeter in thickness, but they have got very, very low thermal conductivity. So, effectively, even though the gas stream is at a much higher air temperature, the effective metal that exists beneath the thermal barrier coating is much colder, and you get thermal grade of the order of about 100 degrees C between the hot and the cold surface. So all of this put together - this whole cooling technology effectively helps to keep the blade below its melting temperature.




    The engine is designed to manage the intense heat in a controlled way, by restricting it to certain components, injecting cool air around the hot parts, and choosing different materials for different parts of the engine. If the engine is severely damaged, doused in jet fuel, and set on fire, none of those mechanisms function; the entire engine (or whatever is left of it), as opposed to just the portions intended to manage heat, will be hot, and none of the cooling mechanisms will be working.






    share|improve this answer











    $endgroup$


















      12












      $begingroup$

      How The Jet Engine Works:




      Inside the typical commercial jet engine, the fuel burns in the combustion chamber at up to 2000 degrees Celsius. The temperature at which metals in this part of the engine start to melt is 1300 degrees Celsius, so advanced cooling techniques must be used.




      You can read more about some of those cooling mechanisms in How are temperature differences handled in a jet engine?



      See also, How do you stop a jet engine melting?:




      Neil - The normal melting point of the nickel blade alloys that we use in the turbine is typically about 12-1400 degrees. But what you do, and this is the clever bit, is you actually cool these blades. You have internal cooling passages, which effectively has air that flows through and it's about 7-800 degrees. And this cooling air then exits from small little minute holes that have been drilled on the surface of the blade and this air then forms a kind of a film on the surface of the blade, and this technology is typically called a 'film cooling.'



      What you also do - you coat these blades and typically use something called a thermal barrier coating. The thermal barrier coating, effectively, is ceramic, typically about quarter of a millimeter in thickness, but they have got very, very low thermal conductivity. So, effectively, even though the gas stream is at a much higher air temperature, the effective metal that exists beneath the thermal barrier coating is much colder, and you get thermal grade of the order of about 100 degrees C between the hot and the cold surface. So all of this put together - this whole cooling technology effectively helps to keep the blade below its melting temperature.




      The engine is designed to manage the intense heat in a controlled way, by restricting it to certain components, injecting cool air around the hot parts, and choosing different materials for different parts of the engine. If the engine is severely damaged, doused in jet fuel, and set on fire, none of those mechanisms function; the entire engine (or whatever is left of it), as opposed to just the portions intended to manage heat, will be hot, and none of the cooling mechanisms will be working.






      share|improve this answer











      $endgroup$
















        12












        12








        12





        $begingroup$

        How The Jet Engine Works:




        Inside the typical commercial jet engine, the fuel burns in the combustion chamber at up to 2000 degrees Celsius. The temperature at which metals in this part of the engine start to melt is 1300 degrees Celsius, so advanced cooling techniques must be used.




        You can read more about some of those cooling mechanisms in How are temperature differences handled in a jet engine?



        See also, How do you stop a jet engine melting?:




        Neil - The normal melting point of the nickel blade alloys that we use in the turbine is typically about 12-1400 degrees. But what you do, and this is the clever bit, is you actually cool these blades. You have internal cooling passages, which effectively has air that flows through and it's about 7-800 degrees. And this cooling air then exits from small little minute holes that have been drilled on the surface of the blade and this air then forms a kind of a film on the surface of the blade, and this technology is typically called a 'film cooling.'



        What you also do - you coat these blades and typically use something called a thermal barrier coating. The thermal barrier coating, effectively, is ceramic, typically about quarter of a millimeter in thickness, but they have got very, very low thermal conductivity. So, effectively, even though the gas stream is at a much higher air temperature, the effective metal that exists beneath the thermal barrier coating is much colder, and you get thermal grade of the order of about 100 degrees C between the hot and the cold surface. So all of this put together - this whole cooling technology effectively helps to keep the blade below its melting temperature.




        The engine is designed to manage the intense heat in a controlled way, by restricting it to certain components, injecting cool air around the hot parts, and choosing different materials for different parts of the engine. If the engine is severely damaged, doused in jet fuel, and set on fire, none of those mechanisms function; the entire engine (or whatever is left of it), as opposed to just the portions intended to manage heat, will be hot, and none of the cooling mechanisms will be working.






        share|improve this answer











        $endgroup$



        How The Jet Engine Works:




        Inside the typical commercial jet engine, the fuel burns in the combustion chamber at up to 2000 degrees Celsius. The temperature at which metals in this part of the engine start to melt is 1300 degrees Celsius, so advanced cooling techniques must be used.




        You can read more about some of those cooling mechanisms in How are temperature differences handled in a jet engine?



        See also, How do you stop a jet engine melting?:




        Neil - The normal melting point of the nickel blade alloys that we use in the turbine is typically about 12-1400 degrees. But what you do, and this is the clever bit, is you actually cool these blades. You have internal cooling passages, which effectively has air that flows through and it's about 7-800 degrees. And this cooling air then exits from small little minute holes that have been drilled on the surface of the blade and this air then forms a kind of a film on the surface of the blade, and this technology is typically called a 'film cooling.'



        What you also do - you coat these blades and typically use something called a thermal barrier coating. The thermal barrier coating, effectively, is ceramic, typically about quarter of a millimeter in thickness, but they have got very, very low thermal conductivity. So, effectively, even though the gas stream is at a much higher air temperature, the effective metal that exists beneath the thermal barrier coating is much colder, and you get thermal grade of the order of about 100 degrees C between the hot and the cold surface. So all of this put together - this whole cooling technology effectively helps to keep the blade below its melting temperature.




        The engine is designed to manage the intense heat in a controlled way, by restricting it to certain components, injecting cool air around the hot parts, and choosing different materials for different parts of the engine. If the engine is severely damaged, doused in jet fuel, and set on fire, none of those mechanisms function; the entire engine (or whatever is left of it), as opposed to just the portions intended to manage heat, will be hot, and none of the cooling mechanisms will be working.







        share|improve this answer














        share|improve this answer



        share|improve this answer








        edited 3 hours ago

























        answered 3 hours ago









        Zach LiptonZach Lipton

        6,17912442




        6,17912442























            6












            $begingroup$

            Peters answer to this question has a nice chart that shows internal jet engine temps:



            enter image description here



            You can see that the temps are highest by a fairly large factor in the combustion chamber. This means that only the combustion chamber needs to be able to withstand those temperatures. To save weight and often use less expensive and less exotic materials the rest of the engine may be made out of materials that don't need to withstand such high temps. As such in an accident where jet fuel may be dispersed in an uncontrolled way and burn with as much oxygen as it can get its easy to scorch engine parts and anything else around.



            It also is in part a question of time. The ability to withstand heat varies with time. In a crash of a fairly fueled aircraft that may burn uncontrolled for a long time you are likely to find scorched parts like this. Where as a plane that runs its tanks try and crashes in a field may not see the same fire marks. However if the plane hits the ground with enough force the heat generated from the impact can also lead to markings like this.






            share|improve this answer











            $endgroup$









            • 4




              $begingroup$
              I'd like to add that there is no point of having a crashed engine survive the crash, +1.
              $endgroup$
              – ymb1
              3 hours ago
















            6












            $begingroup$

            Peters answer to this question has a nice chart that shows internal jet engine temps:



            enter image description here



            You can see that the temps are highest by a fairly large factor in the combustion chamber. This means that only the combustion chamber needs to be able to withstand those temperatures. To save weight and often use less expensive and less exotic materials the rest of the engine may be made out of materials that don't need to withstand such high temps. As such in an accident where jet fuel may be dispersed in an uncontrolled way and burn with as much oxygen as it can get its easy to scorch engine parts and anything else around.



            It also is in part a question of time. The ability to withstand heat varies with time. In a crash of a fairly fueled aircraft that may burn uncontrolled for a long time you are likely to find scorched parts like this. Where as a plane that runs its tanks try and crashes in a field may not see the same fire marks. However if the plane hits the ground with enough force the heat generated from the impact can also lead to markings like this.






            share|improve this answer











            $endgroup$









            • 4




              $begingroup$
              I'd like to add that there is no point of having a crashed engine survive the crash, +1.
              $endgroup$
              – ymb1
              3 hours ago














            6












            6








            6





            $begingroup$

            Peters answer to this question has a nice chart that shows internal jet engine temps:



            enter image description here



            You can see that the temps are highest by a fairly large factor in the combustion chamber. This means that only the combustion chamber needs to be able to withstand those temperatures. To save weight and often use less expensive and less exotic materials the rest of the engine may be made out of materials that don't need to withstand such high temps. As such in an accident where jet fuel may be dispersed in an uncontrolled way and burn with as much oxygen as it can get its easy to scorch engine parts and anything else around.



            It also is in part a question of time. The ability to withstand heat varies with time. In a crash of a fairly fueled aircraft that may burn uncontrolled for a long time you are likely to find scorched parts like this. Where as a plane that runs its tanks try and crashes in a field may not see the same fire marks. However if the plane hits the ground with enough force the heat generated from the impact can also lead to markings like this.






            share|improve this answer











            $endgroup$



            Peters answer to this question has a nice chart that shows internal jet engine temps:



            enter image description here



            You can see that the temps are highest by a fairly large factor in the combustion chamber. This means that only the combustion chamber needs to be able to withstand those temperatures. To save weight and often use less expensive and less exotic materials the rest of the engine may be made out of materials that don't need to withstand such high temps. As such in an accident where jet fuel may be dispersed in an uncontrolled way and burn with as much oxygen as it can get its easy to scorch engine parts and anything else around.



            It also is in part a question of time. The ability to withstand heat varies with time. In a crash of a fairly fueled aircraft that may burn uncontrolled for a long time you are likely to find scorched parts like this. Where as a plane that runs its tanks try and crashes in a field may not see the same fire marks. However if the plane hits the ground with enough force the heat generated from the impact can also lead to markings like this.







            share|improve this answer














            share|improve this answer



            share|improve this answer








            edited 3 hours ago

























            answered 3 hours ago









            DaveDave

            66.8k4125241




            66.8k4125241








            • 4




              $begingroup$
              I'd like to add that there is no point of having a crashed engine survive the crash, +1.
              $endgroup$
              – ymb1
              3 hours ago














            • 4




              $begingroup$
              I'd like to add that there is no point of having a crashed engine survive the crash, +1.
              $endgroup$
              – ymb1
              3 hours ago








            4




            4




            $begingroup$
            I'd like to add that there is no point of having a crashed engine survive the crash, +1.
            $endgroup$
            – ymb1
            3 hours ago




            $begingroup$
            I'd like to add that there is no point of having a crashed engine survive the crash, +1.
            $endgroup$
            – ymb1
            3 hours ago


















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