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Are any jet engines used in combat aircraft water cooled?

How does jet engine water injection work?Which engines are Jet-A used in?How are off-wing jet engines transported?When were the first jet engines used?Could bypass air be used to cool a rocket engine like in turbofans?Can jet engines be used for VTOL civilian aircraft?Why were rotary vane compressors never used in jet engines?Where does turbine vane and blade cooling air come from?How does jet engine water injection work?Is water a possible fuel for jet engines?How much water is carried for jet engine water injection?

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4

1

$begingroup$

Are any jet engines used in combat aircraft water cooled?

If they are not, and instead are air cooled, how can the engine ensure consistent cooling? Wouldn't the airflow passing through whatever radiator implementation it has be greatly affected by the airspeed? Consider low subsonic numbers with heavy maneuvering in a dogfight, vs. mach 2 sustained flight?

While I can imagine that variable air inlet for the radiator would change the airflow, I really have no idea how this would work.

I'm also aware that certain rocket engines, e.g. the F-1 allow the fuel itself to circle around the thrust chamber to cool it. Perhaps a similar system is used in jet engines.

jet-engine

share|improve this question

asked 8 hours ago

AlphaCentauriAlphaCentauri

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add a comment | 

4

1

$begingroup$

Are any jet engines used in combat aircraft water cooled?

If they are not, and instead are air cooled, how can the engine ensure consistent cooling? Wouldn't the airflow passing through whatever radiator implementation it has be greatly affected by the airspeed? Consider low subsonic numbers with heavy maneuvering in a dogfight, vs. mach 2 sustained flight?

While I can imagine that variable air inlet for the radiator would change the airflow, I really have no idea how this would work.

I'm also aware that certain rocket engines, e.g. the F-1 allow the fuel itself to circle around the thrust chamber to cool it. Perhaps a similar system is used in jet engines.

jet-engine

share|improve this question

asked 8 hours ago

AlphaCentauriAlphaCentauri

84411 gold badge44 silver badges1313 bronze badges

$endgroup$

add a comment | 

$begingroup$

Are any jet engines used in combat aircraft water cooled?

If they are not, and instead are air cooled, how can the engine ensure consistent cooling? Wouldn't the airflow passing through whatever radiator implementation it has be greatly affected by the airspeed? Consider low subsonic numbers with heavy maneuvering in a dogfight, vs. mach 2 sustained flight?

While I can imagine that variable air inlet for the radiator would change the airflow, I really have no idea how this would work.

I'm also aware that certain rocket engines, e.g. the F-1 allow the fuel itself to circle around the thrust chamber to cool it. Perhaps a similar system is used in jet engines.

jet-engine

share|improve this question

asked 8 hours ago

AlphaCentauriAlphaCentauri

84411 gold badge44 silver badges1313 bronze badges

$endgroup$

share|improve this question

asked 8 hours ago

AlphaCentauriAlphaCentauri

84411 gold badge44 silver badges1313 bronze badges

share|improve this question

asked 8 hours ago

AlphaCentauriAlphaCentauri

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asked 8 hours ago

AlphaCentauriAlphaCentauri

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asked 8 hours ago

AlphaCentauriAlphaCentauri

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3 Answers
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5

$begingroup$

Jet engines are cooled and temperature managed by the mass air flow itself which is used to surround and limit the boundaries of the flame, keeping it away from the burner can walls, and dilute the heat of the flame as it passes to the turbine (only a minority of the mass airflow's oxygen is actually burned - which is why afterburners work; there's lots of leftover oxygen to work with).

If you're talking about using a closed liquid cooling system with heat exchangers taking heat from the burner can and turbine somehow, well, I've never heard of a water jacketed burner can, and how you could use liquid in a closed system to cool a turbine, who knows.

Liquid cooling was used in the past as supplemental cooling to increase available power by spraying water directly into the mass flow as mentioned here, but in that case the water is a consumable.

share|improve this answer

answered 7 hours ago

John KJohn K

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$endgroup$

add a comment | 

2

$begingroup$

The closest I could find for closed-cyle fluid cooling was a 1975 NASA study for supersonic aircraft, but this used no radiators, and wasn't for the engine. Instead, circulating refrigerant moved heat from the wing and fuselage to the fuel tank containing liquid hydrogen, in the hope that titanium skins could be replaced with cheaper aluminum. The conclusion was that this would help only at airspeeds much greater than Mach 3.

Even for piston-powered aircraft (and NASCAR automobiles for that matter), the drag due to airflow through a radiator is enormous. Some 1930's racing aircraft used radiators inset flush to the wings for this reason.

It may just be that the jet engine's mass airflow suffices, so there's no justification for the extra complexity and weight of a dedicated heat exchanger.

share|improve this answer

answered 7 hours ago

Camille GoudeseuneCamille Goudeseune

42911 silver badge1313 bronze badges

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  A radiator doesn't have to produce a large drag penalty, or even any drag penalty at all - in fact, a properly-designed radiator can actually produce net thrust, by using the air it heats as reaction mass.
  $endgroup$
  – Sean
  3 hours ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  $begingroup$
  Neato! ...it looks like the Meredith Effect has been tried in Formula 1 cars, but not in jet aircraft. Answered another way, because a turbine's combustion isn't blanketed in an enclosed cylinder head, maybe the nonmoving metal parts don't heat up enough to warrant liquid cooling - the airflow is enough. (Sending coolant through the turbine blades seems ghastly complicated.)
  $endgroup$
  – Camille Goudeseune
  3 hours ago
  
  
  

  
  
  
  

add a comment | 

0

$begingroup$

The thing most in need of cooling inside a jet engine is usually the high pressure turbine blades. The air entering the first stage of the turbine is in the neighborhood of 2500F (https://en.wikipedia.org/wiki/Turbine_blade). This is often higher than the melting temperature of the blades themselves. These blades are cooled using air bled off from the high pressure compressor, which is typically at a "cool" temperature of 1000F or so. Water would not be much help in cooling here, as it would instantly vaporize.

share|improve this answer

answered 3 hours ago

Daniel KiracofeDaniel Kiracofe

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$endgroup$

add a comment | 

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5

$begingroup$

Jet engines are cooled and temperature managed by the mass air flow itself which is used to surround and limit the boundaries of the flame, keeping it away from the burner can walls, and dilute the heat of the flame as it passes to the turbine (only a minority of the mass airflow's oxygen is actually burned - which is why afterburners work; there's lots of leftover oxygen to work with).

If you're talking about using a closed liquid cooling system with heat exchangers taking heat from the burner can and turbine somehow, well, I've never heard of a water jacketed burner can, and how you could use liquid in a closed system to cool a turbine, who knows.

Liquid cooling was used in the past as supplemental cooling to increase available power by spraying water directly into the mass flow as mentioned here, but in that case the water is a consumable.

share|improve this answer

answered 7 hours ago

John KJohn K

37.3k11 gold badge6565 silver badges124124 bronze badges

$endgroup$

add a comment | 

5

$begingroup$

Jet engines are cooled and temperature managed by the mass air flow itself which is used to surround and limit the boundaries of the flame, keeping it away from the burner can walls, and dilute the heat of the flame as it passes to the turbine (only a minority of the mass airflow's oxygen is actually burned - which is why afterburners work; there's lots of leftover oxygen to work with).

If you're talking about using a closed liquid cooling system with heat exchangers taking heat from the burner can and turbine somehow, well, I've never heard of a water jacketed burner can, and how you could use liquid in a closed system to cool a turbine, who knows.

Liquid cooling was used in the past as supplemental cooling to increase available power by spraying water directly into the mass flow as mentioned here, but in that case the water is a consumable.

share|improve this answer

answered 7 hours ago

John KJohn K

37.3k11 gold badge6565 silver badges124124 bronze badges

$endgroup$

add a comment | 

$begingroup$

Jet engines are cooled and temperature managed by the mass air flow itself which is used to surround and limit the boundaries of the flame, keeping it away from the burner can walls, and dilute the heat of the flame as it passes to the turbine (only a minority of the mass airflow's oxygen is actually burned - which is why afterburners work; there's lots of leftover oxygen to work with).

If you're talking about using a closed liquid cooling system with heat exchangers taking heat from the burner can and turbine somehow, well, I've never heard of a water jacketed burner can, and how you could use liquid in a closed system to cool a turbine, who knows.

Liquid cooling was used in the past as supplemental cooling to increase available power by spraying water directly into the mass flow as mentioned here, but in that case the water is a consumable.

share|improve this answer

answered 7 hours ago

John KJohn K

37.3k11 gold badge6565 silver badges124124 bronze badges

$endgroup$

share|improve this answer

answered 7 hours ago

John KJohn K

37.3k11 gold badge6565 silver badges124124 bronze badges

answered 7 hours ago

John KJohn K

37.3k11 gold badge6565 silver badges124124 bronze badges

answered 7 hours ago

John KJohn K

37.3k11 gold badge6565 silver badges124124 bronze badges

2

$begingroup$

The closest I could find for closed-cyle fluid cooling was a 1975 NASA study for supersonic aircraft, but this used no radiators, and wasn't for the engine. Instead, circulating refrigerant moved heat from the wing and fuselage to the fuel tank containing liquid hydrogen, in the hope that titanium skins could be replaced with cheaper aluminum. The conclusion was that this would help only at airspeeds much greater than Mach 3.

Even for piston-powered aircraft (and NASCAR automobiles for that matter), the drag due to airflow through a radiator is enormous. Some 1930's racing aircraft used radiators inset flush to the wings for this reason.

It may just be that the jet engine's mass airflow suffices, so there's no justification for the extra complexity and weight of a dedicated heat exchanger.

share|improve this answer

answered 7 hours ago

Camille GoudeseuneCamille Goudeseune

42911 silver badge1313 bronze badges

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  A radiator doesn't have to produce a large drag penalty, or even any drag penalty at all - in fact, a properly-designed radiator can actually produce net thrust, by using the air it heats as reaction mass.
  $endgroup$
  – Sean
  3 hours ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  $begingroup$
  Neato! ...it looks like the Meredith Effect has been tried in Formula 1 cars, but not in jet aircraft. Answered another way, because a turbine's combustion isn't blanketed in an enclosed cylinder head, maybe the nonmoving metal parts don't heat up enough to warrant liquid cooling - the airflow is enough. (Sending coolant through the turbine blades seems ghastly complicated.)
  $endgroup$
  – Camille Goudeseune
  3 hours ago
  
  
  

  
  
  
  

add a comment | 

2

$begingroup$

The closest I could find for closed-cyle fluid cooling was a 1975 NASA study for supersonic aircraft, but this used no radiators, and wasn't for the engine. Instead, circulating refrigerant moved heat from the wing and fuselage to the fuel tank containing liquid hydrogen, in the hope that titanium skins could be replaced with cheaper aluminum. The conclusion was that this would help only at airspeeds much greater than Mach 3.

Even for piston-powered aircraft (and NASCAR automobiles for that matter), the drag due to airflow through a radiator is enormous. Some 1930's racing aircraft used radiators inset flush to the wings for this reason.

It may just be that the jet engine's mass airflow suffices, so there's no justification for the extra complexity and weight of a dedicated heat exchanger.

share|improve this answer

answered 7 hours ago

Camille GoudeseuneCamille Goudeseune

42911 silver badge1313 bronze badges

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  A radiator doesn't have to produce a large drag penalty, or even any drag penalty at all - in fact, a properly-designed radiator can actually produce net thrust, by using the air it heats as reaction mass.
  $endgroup$
  – Sean
  3 hours ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  $begingroup$
  Neato! ...it looks like the Meredith Effect has been tried in Formula 1 cars, but not in jet aircraft. Answered another way, because a turbine's combustion isn't blanketed in an enclosed cylinder head, maybe the nonmoving metal parts don't heat up enough to warrant liquid cooling - the airflow is enough. (Sending coolant through the turbine blades seems ghastly complicated.)
  $endgroup$
  – Camille Goudeseune
  3 hours ago
  
  
  

  
  
  
  

add a comment | 

$begingroup$

The closest I could find for closed-cyle fluid cooling was a 1975 NASA study for supersonic aircraft, but this used no radiators, and wasn't for the engine. Instead, circulating refrigerant moved heat from the wing and fuselage to the fuel tank containing liquid hydrogen, in the hope that titanium skins could be replaced with cheaper aluminum. The conclusion was that this would help only at airspeeds much greater than Mach 3.

Even for piston-powered aircraft (and NASCAR automobiles for that matter), the drag due to airflow through a radiator is enormous. Some 1930's racing aircraft used radiators inset flush to the wings for this reason.

It may just be that the jet engine's mass airflow suffices, so there's no justification for the extra complexity and weight of a dedicated heat exchanger.

share|improve this answer

answered 7 hours ago

Camille GoudeseuneCamille Goudeseune

42911 silver badge1313 bronze badges

$endgroup$

share|improve this answer

answered 7 hours ago

Camille GoudeseuneCamille Goudeseune

42911 silver badge1313 bronze badges

answered 7 hours ago

Camille GoudeseuneCamille Goudeseune

42911 silver badge1313 bronze badges

answered 7 hours ago

Camille GoudeseuneCamille Goudeseune

42911 silver badge1313 bronze badges

0

$begingroup$

The thing most in need of cooling inside a jet engine is usually the high pressure turbine blades. The air entering the first stage of the turbine is in the neighborhood of 2500F (https://en.wikipedia.org/wiki/Turbine_blade). This is often higher than the melting temperature of the blades themselves. These blades are cooled using air bled off from the high pressure compressor, which is typically at a "cool" temperature of 1000F or so. Water would not be much help in cooling here, as it would instantly vaporize.

share|improve this answer

answered 3 hours ago

Daniel KiracofeDaniel Kiracofe

3,62777 silver badges2323 bronze badges

$endgroup$

add a comment | 

0

$begingroup$

The thing most in need of cooling inside a jet engine is usually the high pressure turbine blades. The air entering the first stage of the turbine is in the neighborhood of 2500F (https://en.wikipedia.org/wiki/Turbine_blade). This is often higher than the melting temperature of the blades themselves. These blades are cooled using air bled off from the high pressure compressor, which is typically at a "cool" temperature of 1000F or so. Water would not be much help in cooling here, as it would instantly vaporize.

share|improve this answer

answered 3 hours ago

Daniel KiracofeDaniel Kiracofe

3,62777 silver badges2323 bronze badges

$endgroup$

add a comment | 

$begingroup$

The thing most in need of cooling inside a jet engine is usually the high pressure turbine blades. The air entering the first stage of the turbine is in the neighborhood of 2500F (https://en.wikipedia.org/wiki/Turbine_blade). This is often higher than the melting temperature of the blades themselves. These blades are cooled using air bled off from the high pressure compressor, which is typically at a "cool" temperature of 1000F or so. Water would not be much help in cooling here, as it would instantly vaporize.

share|improve this answer

answered 3 hours ago

Daniel KiracofeDaniel Kiracofe

3,62777 silver badges2323 bronze badges

$endgroup$

share|improve this answer

answered 3 hours ago

Daniel KiracofeDaniel Kiracofe

3,62777 silver badges2323 bronze badges

answered 3 hours ago

Daniel KiracofeDaniel Kiracofe

3,62777 silver badges2323 bronze badges

answered 3 hours ago

Daniel KiracofeDaniel Kiracofe

3,62777 silver badges2323 bronze badges