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

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

Why do gases in the combustion chamber only flow one direction to the gas turbine in a jet engine?How are temperature differences handled in a jet engine?WHY does a jet engine work?What does the actual path of air within a turbojet engine look like?Why does NASA's B-52 008 have a smoking engine in this photograph?Why does intake of turbofan engine have angle of attack?Why does gas turbine engine have pressure oil supply tube and the scavenge oil tube?Is it possible to build a jet engine that utilises all excess heat?Are there any airliners and or aircraft that use bleed air and excess heat from the engine to prevent icingWhy did the turbojet replace the piston engine?Does Rolls Royce produce any engine that matches the capabilities of the GE9x?Why does the Convair 990 produce this howling sound during landing?

2

$begingroup$

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?

(bostonherald.com)

jet-engine accidents aerospace-materials

share|improve this question

edited 37 mins ago

ymb1

66.9k7212355

asked 46 mins ago

RegmiRegmi

1586

$endgroup$

• 
  
  
  

  
  1
  

  
  
  
  
  
  

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

  
  
  
  

add a comment | 

2

$begingroup$

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?

(bostonherald.com)

jet-engine accidents aerospace-materials

share|improve this question

edited 37 mins ago

ymb1

66.9k7212355

asked 46 mins ago

RegmiRegmi

1586

$endgroup$

• 
  
  
  

  
  1
  

  
  
  
  
  
  

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

  
  
  
  

add a comment | 

$begingroup$

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?

(bostonherald.com)

jet-engine accidents aerospace-materials

share|improve this question

edited 37 mins ago

ymb1

66.9k7212355

asked 46 mins ago

RegmiRegmi

1586

$endgroup$

share|improve this question

edited 37 mins ago

ymb1

66.9k7212355

asked 46 mins ago

RegmiRegmi

1586

share|improve this question

edited 37 mins ago

ymb1

66.9k7212355

asked 46 mins ago

RegmiRegmi

1586

edited 37 mins ago

ymb1

66.9k7212355

edited 37 mins ago

ymb1

66.9k7212355

asked 46 mins ago

RegmiRegmi

1586

asked 46 mins ago

RegmiRegmi

1586

2 Answers
2

active

oldest

votes

3

$begingroup$

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

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

edited 32 mins ago

answered 38 mins ago

DaveDave

66.8k4125241

$endgroup$

• 
  
  
  

  
  3
  

  
  
  
  
  
  

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

  
  
  
  

add a comment | 

3

$begingroup$

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

edited 27 mins ago

answered 30 mins ago

Zach LiptonZach Lipton

6,08912441

$endgroup$

add a comment | 

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3

$begingroup$

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

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

edited 32 mins ago

answered 38 mins ago

DaveDave

66.8k4125241

$endgroup$

• 
  
  
  

  
  3
  

  
  
  
  
  
  

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

  
  
  
  

add a comment | 

3

$begingroup$

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

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

edited 32 mins ago

answered 38 mins ago

DaveDave

66.8k4125241

$endgroup$

• 
  
  
  

  
  3
  

  
  
  
  
  
  

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

  
  
  
  

add a comment | 

$begingroup$

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

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

edited 32 mins ago

answered 38 mins ago

DaveDave

66.8k4125241

$endgroup$

share|improve this answer

edited 32 mins ago

answered 38 mins ago

DaveDave

66.8k4125241

answered 38 mins ago

DaveDave

66.8k4125241

answered 38 mins ago

DaveDave

66.8k4125241

3

$begingroup$

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

edited 27 mins ago

answered 30 mins ago

Zach LiptonZach Lipton

6,08912441

$endgroup$

add a comment | 

3

$begingroup$

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

edited 27 mins ago

answered 30 mins ago

Zach LiptonZach Lipton

6,08912441

$endgroup$

add a comment | 

$begingroup$

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

edited 27 mins ago

answered 30 mins ago

Zach LiptonZach Lipton

6,08912441

$endgroup$

share|improve this answer

edited 27 mins ago

answered 30 mins ago

Zach LiptonZach Lipton

6,08912441

answered 30 mins ago

Zach LiptonZach Lipton

6,08912441

answered 30 mins ago

Zach LiptonZach Lipton

6,08912441