Chinese Engine Development

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Godzilla said:
Not really cross applicable though. One is going for creep strength under high temps, while the other is going for light weight and impact strength. They are using carbon fibres nowadays instead of titanium alloys for the fan blades, with maybe titanium alloy at the leading edge to help with impact resistance, while for the turbine we are still on the nickel super alloys. Sorry the fan material isn't my field since i have only been playing with GTs, but they are in completely different fields to the turbines.
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I feel like if the issue is using research as a proxy of broader development, then if the coating and cooling research is fairly advanced, that should indicate the rest of the development is fairly advanced, no?
 
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latenlazy

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SleepyStudent said:
I feel like if the issue is using research as a proxy of broader development, then if the coating and cooling research is fairly advanced, that should indicate the rest of the development is fairly advanced, no?
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Yup.
Godzilla said:
Not really cross applicable though. One is going for creep strength under high temps, while the other is going for light weight and impact strength. They are using carbon fibres nowadays instead of titanium alloys for the fan blades, with maybe titanium alloy at the leading edge to help with impact resistance, while for the turbine we are still on the nickel super alloys. Sorry the fan material isn't my field since i have only been playing with GTs, but they are in completely different fields to the turbines.
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And to the point above, there’s also pretty visible research output on carbon fiber as well as ceramic fan blades.
 
Deino

Deino

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Guys ... are we still in the Chinese engine section or is this more a general engine technology related discussion?
 
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latenlazy

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Deino said:
Guys ... are we still in the Chinese engine section or is this more a general engine technology related discussion?
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I would make the case here that increasing general literacy on how these engines work and what technology goes into them will make it much easier for us to parse and identify relevant information about China’s own engine projects. There may be developments we miss simply due to the fact that progress in component technologies are overlooked or misunderstood. Before you go looking you have to know what to look for, and not every substantive piece of information is going to have “major Chinese engine project” headlining it.
 
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Tirdent

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latenlazy said:
I think a lot of those techniques are cross applicable though no? Sure the pairings of the materials are going to be different, but my point is just that if you survey what’s currently being published in research cooling and coating are actively on the radar as domains being developed.
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Not really. Aerodynamics? Decelerating diffusor flow (compressors/fans) vs. accelerating nozzle flow (turbines), with all the attendant consequences for the viscous boundary layer. That's in essence why large engines (too much mass flow to use high-PR centrifugal compressors) generally have far more compressor stages than turbine stages, BTW. Add the cooling air jets emanating from the turbine blades and interacting with the exhaust gas flow and it's a very different problem set.

Materials? In addition to the temperature/strength interplay that has been mentioned already, there's also high temperature corrosion (chemical oxidation) to consider. This is why even stationary nozzle guide vanes (which are not subject to the high centrifugal loads seen in the rotor blading which result in creep issues) are typically single crystal. It improves resistance to chemical attack, in addition to the better mechanical properties.

latenlazy said:
And to the point above, there’s also pretty visible research output on carbon fiber as well as ceramic fan blades.
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Carbon fiber fan blades, but surely ceramic *turbine* blades? Ceramics have good temperature tolerance and chemical corrosion resistance, but impact strength is unsuitable for a fan.
 
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latenlazy

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Tirdent said:
Not really. Aerodynamics? Decelerating diffusor flow (compressors/fans) vs. accelerating nozzle flow (turbines), with all the attendant consequences for the viscous boundary layer. That's in essence why large engines (too much mass flow to use high-PR centrifugal compressors) generally have far more compressor stages than turbine stages, BTW. Add the cooling air jets emanating from the turbine blades and interacting with the exhaust gas flow and it's a very different problem set.

Materials? In addition to the temperature/strength interplay that has been mentioned already, there's also high temperature corrosion (chemical oxidation) to consider. This is why even stationary nozzle guide vanes (which are not subject to the high centrifugal loads seen in the rotor blading which result in creep issues) are typically single crystal. It improves resistance to chemical attack, in addition to the better mechanical properties.



Carbon fiber fan blades, but surely ceramic *turbine* blades? Ceramics have good temperature tolerance and chemical corrosion resistance, but impact strength is unsuitable for a fan.
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Remember, my point was that there is a clear indication about where the *general* direction of research has been. It’s very unlikely that they’d be looking into coatings for fan blades and be completely oblivious to similar applications for other parts of the engine. I could dig around for research specifically on turbine blade materials but I only noticed the research on coating for fan blades because I was mostly interested in exploring where China was on compressors.

Wrt to ceramic blades (which I think is still mostly focused on compressors) China isn’t the only country looking into this. I have a friend in the US who worked on research on ceramics for use in engine blades when he was still in academia. If you asked me CMCs are obviously much more feasible than pure ceramics, *but* the point is that this sort of research is being done in China.
 
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Tirdent

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I don't think the new nozzles are longer externally (although the divergent section inside certainly seems to be), only the hinged flaps are. Makes it look a bit like a cross between the EJ200 and P&W F100!
 
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