Chinese Engine Development

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latenlazy

Brigadier
tphuang said:
keep in mind that the official number of F-119 is classified. The stated dry thrust of F-119 is a lot higher than what you'd expect from an engine of T/W ratio of 9 with A/B. A successful WS-15 project probably only gets you to the same level as a mature F-119 (which would've been probably mid to late 2000s technology for PW). And then also consider how many years it took China to go from WS-10 to WS-10C. We are looking at about 10 years of development for the 16% thrust increase. So yes, even if the tech leap from F-119 to F-135 is not huge (which someone like myself without engine experience can't quantity), increasing T/W by that much while also improving its fuel efficiency can take many years to do.

Of course, there is the possibility that due to its experience with WS-10, China will be able to go from baseline WS-15 to a higher T/W version in shorter time than with WS-10 project, but we won't know that for a while.
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If the stated dry thrust of the F-119 is higher than 105-110 kn, the thrust increase of the F135 is even less impressive. But from the standpoint of jet engine capabilities if you increase thrust by increasing the bypass ratio you’re actually not increasing the basic capabilities of your engine tech very much.

Wrt to what the WS-10’s improvements can tell us about the WS-15’s level of technology, the GE F110’s continuous thrust improvements come from using a 4th gen design with 5th gen materials. If the WS-10 has seen a comparable advancement to what the F110 has seen, that suggests the latest WS-10 variants also use 5th gen materials, which suggests a decent degree of maturity for 5th gen component technologies.
 
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sndef888

Senior Member
Registered Member
latenlazy said:
If the stated dry thrust of the F-119 is higher than 105-110 kn, the thrust increase of the F135 is even less impressive. But from the standpoint of jet engine capabilities if you increase thrust by increasing the bypass ratio you’re actually not increasing the basic capabilities of your engine tech very much.

Wrt to what the WS-10’s improvements can tell us about the WS-15’s level of technology, the GE F110’s continuous thrust improvements come from using a 4th gen design with 5th gen materials. If the WS-10 has seen a comparable advancement to what the F110 has seen, that suggests the latest WS-10 variants also use 5th gen materials, which suggests a decent degree of maturity for 5th gen component technologies.
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Sorry for the noob question, but if thrust is increased by simply increasing bypass ratio why doesn't china just do that

Are there negative consequences to it
 
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latenlazy

Brigadier
sndef888 said:
Sorry for the noob question, but if thrust is increased by simply increasing bypass ratio why doesn't china just do that

Are there negative consequences to it
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Higher bypass is less efficient at higher speeds, and can also reduce your achievable top speed in dry thrust. If you want efficient supercruise you need to go with low bypass. There’s a reason why the F-35 doesn’t supercruise despite having more powerful engines.
 
Godzilla

Godzilla

Junior Member
Registered Member
latenlazy said:
If the stated dry thrust of the F-119 is higher than 105-110 kn, the thrust increase of the F135 is even less impressive. But from the standpoint of jet engine capabilities if you increase thrust by increasing the bypass ratio you’re actually not increasing the basic capabilities of your engine tech very much.

Wrt to what the WS-10’s improvements can tell us about the WS-15’s level of technology, the GE F110’s continuous thrust improvements come from using a 4th gen design with 5th gen materials. If the WS-10 has seen a comparable advancement to what the F110 has seen, that suggests the latest WS-10 variants also use 5th gen materials, which suggests a decent degree of maturity for 5th gen component technologies.
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Mate, F-119 has a turbine inlet temperature of 1650C, while F-135 is 1900C. If this isn't impressive I don't know what is!
After all, they are all Brayton cycle engines are you can only bump the thrust either through the bypass ratio or turbine inlet temp.
I highly doubt WS-10 uses 5th gen material, we got to be a little realistic here.
End of the day, from the maintenance issues we hear with the F-135, they probably hit 1900C at the detriment to the fatigue life of the blades.
 
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latenlazy

Brigadier
Godzilla said:
Mate, F-119 has a turbine inlet temperature of 1650C, while F-135 is 1900C. If this isn't impressive I don't know what is!
After all, they are all Brayton cycle engines are you can only bump the thrust either through the bypass ratio or turbine inlet temp.
I highly doubt WS-10 uses 5th gen material, we got to be a little realistic here.
End of the day, from the maintenance issues we hear with the F-135, they probably hit 1900C at the detriment to the fatigue life of the blades.
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TIT increase is directly related to materials improvements, not engine cycle design improvements. The two most fundamental factors that drive advance of Brayton cycle engine performance are temperature and air compression efficiency. The latter needs material and engine cycle design improvements while the former can be achieved with just better materials.

Improvements in air compression cycle efficiency is what’s responsible for the jump in both total thrust and T:W ratio from 4th Gen engines to 5th gen engines. That’s what’s drove the jump from ~125 kN engines like the F100 and F110 to the ~160-180 kN range engines like the F119 and F135.

TIT related improvements meanwhile are responsible for driving the F110’s thrust from ~125 kn to 145 kn. In the F135’s case TIT increase is most probably to drive the larger first stage fan while improving fuel efficiency, and is not so much the main factor responsible for driving up thrust gains based on the fact that the dry thrust gain seems to scale linearly with bypass ratio increase relative to the F119. And they could afford to do this *because* they’re probably using materials that don’t impact their blade fatigue life requirements. These things are directly specced by requirements.

Going back to the F110, that engine could increase its thrust from ~125 kN to ~145 kN because it uses 5th gen engine materials to allow it to run hotter, while still using an older engine cycle design. The WS-10 is the same generation of engine cycle design (and actually not just the same generation, but the same lineage). How else do you propose the WS-10 made the same performance gains if it isn’t using 5th gen materials?
 
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Godzilla

Godzilla

Junior Member
Registered Member
latenlazy said:
TIT increase is directly related to materials improvements, not engine cycle design improvements. The two most fundamental factors that drive advance of Brayton cycle engine performance are temperature and air compression efficiency. The latter needs material and engine cycle design improvements while the former can be achieved with just better materials.

Improvements in air compression cycle efficiency is what’s responsible for the jump in both total thrust and T:W ratio from 4th Gen engines to 5th gen engines. That’s what’s drove the jump from ~125 kN engines like the F100 and F110 to the ~160-180 kN range engines like the F119 and F135.

TIT related improvements meanwhile are responsible for driving the F110’s thrust from ~125 kn to 145 kn. In the F135’s case TIT increase is most probably to drive the larger first stage fan while improving fuel efficiency, and is not so much the main factor responsible for driving up thrust gains based on the fact that the dry thrust gain seems to scale linearly with bypass ratio increase relative to the F119. And they could afford to do this *because* they’re probably using materials that don’t impact their blade fatigue life requirements. These things are directly specced by requirements.

Going back to the F110, that engine could increase its thrust from ~125 kN to ~145 kN because it uses 5th gen engine materials to allow it to run hotter, while still using an older engine cycle design. The WS-10 is the same generation of engine cycle design (and actually not just the same generation, but the same lineage). How else do you propose the WS-10 made the same performance gains if it isn’t using 5th gen materials?
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My material's design creep life of 200 hours vs 500 hours vs 5000 hours is going to have a say in how hot I can run it. You'll sacrifice reliability and alot less mean time between overhaul to achieve the same thrust to weight ratio. There is no getting around the material science unless you want to treat your engines like throw aways.
 
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latenlazy

Brigadier
Godzilla said:
My material's design creep life of 200 hours vs 500 hours vs 5000 hours is going to have a say in how hot I can run it. You'll sacrifice reliability and alot less mean time between overhaul to achieve the same thrust to weight ratio. There is no getting around the material science unless you want to treat your engines like throw aways.
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The engine mean time to maintenance requirements will shape the hard line by which the balance of material fatigue time and designed operation temperature are considered. They wouldn’t increase the TIT for the F135 if they couldn’t meet mean time to maintenance requirements.
 
Godzilla

Godzilla

Junior Member
Registered Member
latenlazy said:
The engine mean time to maintenance requirements will shape the hard line by which the balance of material fatigue time and designed operation temperature are considered. They wouldn’t increase the TIT for the F135 if they couldn’t meet mean time to maintenance requirements.
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I was more thinking along that line for WS-10 for hitting those thrust to weight ratios. Reasoning is, if there has been a major breakthrough, the flow on to the commercial applications would have spread especially in publications.

Also, given that we are pushing the material science so much on the F135, the real world performance of the material casting, thermal barrier coating cracking, air cooling etc would really push the maintenance requirement compared to planned. We are seeing these problems right now I believe. Physics after all applies to everyone.
 
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