COMAC C919
- Thread starter Deino
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With this, I wrote a casual thread on Twitter but included more details, including a breakdown of Yankee's claims from 2018. Cheers @sunnymaxi for helping me out with the TiAl section and @interestedseal for posting the sources here.
didn't you read this thread i m quoting down below ?? current CJ-1000A is pretty much a different machine with massive improvement over the years include design, core machine and increase bypass ratio.
in 2018 article it was mentioned, CJ-1000A biggest limitation was the material. also low pressure turbine blades material. later in 2021 Institute of Metal research successfully developed TiAl low pressure turbine blades and successfully broke the monopoly. then they took a step further and casting 3D printed TiAl low pressure turbine blades. which even LEAP engine don't have.
@Alfa_Particle basically clarify this thing in last page.
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Yeah, I read it. Very carefully. Circa 2018, the CJ-1000A had an inferior architecture to the LEAP-1C, now it has an identical architecture. My question is how it gets 7% better TSFC? Something about it has to be significantly better. Yes, QBeam's SEBM TiAl blades are very neat, but that doesn't move the needle that far.
If the dynamic loads on the turbine are lighter for the same amount of mechanical and thermal work you will get more efficiency. Weight savings specifically on rotating components in the turbine can stack up pretty quickly for fuel economy. The other possibility is just greater thermal efficiency from the combustor. Shave a percentage point here and a percentage point there and it’s not very hard to get to 7% improvement.
@latenlazy already got there before me. The ACAE/COMAC guy cited "there are a myriad of ways, including increasing the combustor temperature (TiT?) for even more complete combustion and higher efficiency + improving the compatibility between the LPT and the fan too (which is what @latenlazy said about lighter dynamic loads for the same mechanical and thermal work, or alternatively getting squeezing more mechanical and thermal work out of similar dynamic loads)."
I'll add that, although it's a complete guess based on absolutely zero evidence, it's possible that the CJ1000A incorporated contra-rotating spools like the WS-10/F119 family. Unlike the PW1000G which also has contra-rotating spools, the LEAP family did not incorporate this. This kind of architecture has weight-saving and efficiency implications via gyroscopic cancellation (you need less robust bearings and potentially eliminate some stators), higher efficiency, and higher compression ratios.
It'll also be interesting to see how other aspects of CJ-1000A compares to the latest western products like LEAP-1 such as lifespan, reliability and economics.
We've long heard rumors from Chinese sources that Chinese engines have surpassed Russian designs and reached near or complete parity with the latest western engine. With the CJ-1000A allegedly only a month or so away from getting it's TC and soon able to power C919 on commercial verification flights, we'll likely get more information on the specifics of the engine and see how much these rumors are true.
We've long heard rumors from Chinese sources that Chinese engines have surpassed Russian designs and reached near or complete parity with the latest western engine. With the CJ-1000A allegedly only a month or so away from getting it's TC and soon able to power C919 on commercial verification flights, we'll likely get more information on the specifics of the engine and see how much these rumors are true.
Well, according to @9x9走向商业成功之路 who AFAIK is one of the more credible followers (and possibly insider) of COMAC and it's products on the Chinese internet doesn't seem to buy into whatever that article claims.
He claims original timeline is 2027 for TC though apparently it'll be difficult to reach and possibly will be delayed even further.
He also quoted the entire conversation on the CJ-1000A article posted here and it's claims and said:
"The more rumors there are, the more realistic they sound yet that doesn't change the fact that they are all false rumors"
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i have been following him for years. and 老王RR涡扇花动机 too.
老王RR涡扇花动机 is more credible when it comes to ACAE (the commercial branch of AECC). he has given the date of 2028 for commercial service if everything goes well. and regarding first flight with C919. exact date nobody knows. so let see