Chinese Engine Development


gelgoog

Captain
Registered Member
...
Russia does not export more advanced engines to China
The D-30 engine is not advanced. Compared with the new-generation engine, its duct is relatively small and the fuel consumption rate is high. Russia’s newly improved Il 476 transport aircraft has replaced the D-30 with a more advanced PS-90 engine. Russian media claimed that Russia has refused to export PS-90 engines to China. The D-30 is currently China's only usable turbofan engine with no afterburner bypass ratio. The US media called the localized model WS-18. Currently, China's three main combat models: Il-76, H6K "God of War", and Yun-20 are all equipped with D-30 series engines.

A lot of PS-90 engine versions cannot be exported easily. They use Western components.

The Russians have a limited production capacity for the PS-90. The D-30 engine is also a lot cheaper to produce. That is one reason why the Russians have been taking forever to manufacture the Il-76 with PS-90 engines.

Also the initial production of PD-14 engines for example was only 4 engines a year. Only recently did they open up a new modern test facility for PD-14.

1617995033095.png
An old picture with the WS-20 on an Il-76 test aircraft.
 

Tirdent

Junior Member
Registered Member
The only PS-90 version with any Western content whatsoever was the PS-90A2, which never entered production for precisely that reason. As did most planned variants actually, apart from the industrial gas turbine, all production models were minor derivatives of the base model. The PS-90A76 is simply identical hardware derated to 14.5tf, the PS-90A1 has a new HPT to cope (sort of - its average time on wing is markedly shorter!) with the higher TIT at the increased 18tf rating. That's basically it.

It's an interesting question why Russia never sold any PS-90s to China, considering that the engine has been exported quite a bit actually (India, Jordan, Azerbaijan, Cuba, North Korea*). My guess is that it's a combination of lack of opportunity (the failure of that 38 airframe Il-76/78 order in the 2000s) and then concern about competition from the Y-20 project that resulted. Because now that the latter has competitive engines, I doubt the new-built Il-76MD-90A (Il-476) will stand much of a chance on the export market, unless the Y-20 is unavailable.

As for the PD-14, none of its applications (MS-21, Il-276) has entered production yet.

* Exporting to North Korea an engine with too much Western content for Chinese sales? I think not ;)
 
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Godzilla

New Member
Registered Member
Well I found this explanation

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In almost every large turbofan I see, the LP turbine stages outnumber the HP turbine stages by a factor of at least 2. Here's a photo of the RR Trent 900:
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The Trent 900 (like most Rolls-Royce turbofans) is a 3-spool turbofan, rather than a 2-spool. But even here, my observation holds. There are far more LP turbine stages than the middle or high pressure stages.
Why is this?

Because the LP turbine extracts power for the fan, which requires the most power. The HP and IP turbine only extract power for their connected compressors - the LP turbine extracts power for the fan and the LP compressor. The fan does work on all airflow through the engine, the compressors only on a fraction (10:1 for a high bypass like the Trent 1000). The fan produces up to 75% of the thrust of the engine.

From
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: the cross section of the Trent 1000. It shows that the LP, IP and HP rotors have different rotational speeds, but does not list them. Another (older) presentation lists them as 3600. 6800 and 10200 RPM. Rotational speed goes down as the volume of the mass stream goes up.

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An old textbook of mine gives the power P extracted from a turbine stage as:



P=m˙⋅u⋅vax⋅[tan(α2)+tan(α3)]P=m˙⋅u⋅vax⋅[tan(α2)+tan(α3)]


with

  • m˙m˙ = mass flow [kg/s]
  • u = tangential blade velocity [m/s]
  • vaxax = axial gas velocity [m/s]
  • α2α2 and α3α3 angles according to the figure below.
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So the tangential speed of the turbine blade is in the equation for power extraction, which is composed of rotational velocity and blade radius. The faster the turbine turns, the more power can be extracted per stage, and the fewer stages required. Why then does rotational velocity go down with pressure? (HP = 10,200; IP = 6,800).

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The reason is the constructional limits of the turbine. As the gas stream expands, the turbine blades become larger and are mounted at a greater axial distance, which results in greater centrifugal forces which are proportional to blade mass, rotational speed and distance from the axis. In order to limit centrifugal forces, the rotational velocity of the rotor is reduced: each subsequent stage turns at a lower RPM. Notice that a lower RPM can be compensated by mounting the blade further away from the rotational axis.

The LP rotor of an un-geared engine runs at the same rotational velocity as the fan. Its optimal RPM for the turbine may be higher, and that can be accommodated by the geared fan. As the bypass ratio gets higher, the LP turbine will be extracting a higher fraction of total power from the airstream - turboprops and turboshafts have a gearbox in between the LP shaft and the propeller/rotor, and the high bypass fan approaches the relative dimensions of a propeller...
The LP compressor stages is directly related to the fan diameter/bypass ratio exactly per what you said. Trent 700 had a bypass ratio of 5, and it had 4 LP stages, Trent 1000 has a bypass ratio of 10, so it needs 6 LP stages.
Kind of funny that you used the Trent as an example. I think RR is replacing the trent with the ultrafan in the future, getting rid of the LP completely and going with the geared. Not sure if it still qualifies as a 3 spool engine though they still called the second stage IP. The trent 7000 has the gearbox though, and still the 6 stage IP. They are pushing the limits a bit too far though, as I heard the IP and HP blades are causing alot of problem on the newer trents. They should have gone for the lower hanging fruits like getting rid of the shrouds instead.. Are the Chinese engines shrouded or shroudless? (both for turbine stages and for the fan)
 

gelgoog

Captain
Registered Member
The only PS-90 version with any Western content whatsoever was the PS-90A2, which never entered production for precisely that reason. As did most planned variants actually, apart from the industrial gas turbine, all production models were minor derivatives of the base model. The PS-90A76 is simply identical hardware derated to 14.5tf, the PS-90A1 has a new HPT to cope (sort of - its average time on wing is markedly shorter!) with the higher TIT at the increased 18tf rating. That's basically it.

It's an interesting question why Russia never sold any PS-90s to China, considering that the engine has been exported quite a bit actually (India, Jordan, Azerbaijan, Cuba, North Korea*). My guess is that it's a combination of lack of opportunity (the failure of that 38 airframe Il-76/78 order in the 2000s) and then concern about competition from the Y-20 project that resulted. Because now that the latter has competitive engines, I doubt the new-built Il-76MD-90A (Il-476) will stand much of a chance on the export market, unless the Y-20 is unavailable.

As for the PD-14, none of its applications (MS-21, Il-276) has entered production yet.

* Exporting to North Korea an engine with too much Western content for Chinese sales? I think not ;)

From what I understand they only manufactured the PS-90A2 or similar to power the Tu-204SM prototype. Those exports, I think, use the original PS-90 or A1. But like I said the production rate was never that high to begin with. For example the maximum production rate per year of the Il-96 was 3 aircraft in 1994. That is a quad-engine. The maximum production rate of the Tu-204 was 10 aircraft in 2008. That is a dual-engine. Unlike civilian airliners a military transport isn't continuously operating. Plus Russia has its own oil. So fuel consumption is a minor concern and engine cost is a lot more important.
 

BoraTas

Junior Member
Registered Member
The LP compressor stages is directly related to the fan diameter/bypass ratio exactly per what you said. Trent 700 had a bypass ratio of 5, and it had 4 LP stages, Trent 1000 has a bypass ratio of 10, so it needs 6 LP stages.
Kind of funny that you used the Trent as an example. I think RR is replacing the trent with the ultrafan in the future, getting rid of the LP completely and going with the geared. Not sure if it still qualifies as a 3 spool engine though they still called the second stage IP. The trent 7000 has the gearbox though, and still the 6 stage IP. They are pushing the limits a bit too far though, as I heard the IP and HP blades are causing alot of problem on the newer trents. They should have gone for the lower hanging fruits like getting rid of the shrouds instead.. Are the Chinese engines shrouded or shroudless? (both for turbine stages and for the fan)
Ultrafan is an extremely ambitious project. Its projected specs are:
3 shafts
15:1 BPR
70:1 compression ratio
High TIT (2000 C ?)
Reduction gear
Variable-pitch fan
composite fan and fan case
Advanced titanium alloy blisk low-pressure compressors (LPC)
Heavy use of intermetallics in HPC, LPT and the nozzle
CMC in HPT/IPT stators and combustion chamber liner
Twin-annular, pre-swirling lean-burn combustor
Heavy use of 3d printing

It is almost like they are attempting to regain their position against GE and P&W. They are targeting a breakthrough in all parts. They will probably run out of money while doing this. Maybe China can help with that one:D
 

gelgoog

Captain
Registered Member
Well, I doubt the current government would inject the necessary cash.

RR already had a do or die moment with the RB211. At the time the UK government saved the company and thus a significant part of the industry. But the rot can already be seen with the F-35s the UK is buying not having a UK engine. That would likely not have happened in the past. The fact is that RR is the last engine manufacture in Western Europe which can really compete with the US firms in the commercial transportation sector. I doubt the current transportation crisis has helped their prospects either. There is already talk of a possible spin-off or bankruptcy of the GE aviation turbine business.
 

Tirdent

Junior Member
Registered Member
But like I said the production rate was never that high to begin with. For example the maximum production rate per year of the Il-96 was 3 aircraft in 1994. That is a quad-engine. The maximum production rate of the Tu-204 was 10 aircraft in 2008. That is a dual-engine. Unlike civilian airliners a military transport isn't continuously operating. Plus Russia has its own oil. So fuel consumption is a minor concern and engine cost is a lot more important.

We digress, but...

It's not like they could not have built more - the sluggish sales of the airframes using it just didn't support a higher rate. After prolonged teething troubles caused by this slow learning curve, the fuel consumption and reliability statistics on the PS-90A are pretty respectable though. It's easy to forget that it is essentially a 1980s engine, so it's no use comparing it to newer engines like the Trent 800 or GE90, let alone the GEnx or something.

Relative to contemporaries of the same thrust class (PW2000, 535-series RB.211) fuel consumption matches the RR and reliability* approaches the P&W. With the PW2000 therefore having better fuel consumption and the RB.211 much better reliability, it is easy to dismiss this as the worst of both worlds, and commercially that is of course what happened. But the point is that it's in the ball park, and that's no mean feat for a manufacturer that was hopelessly outclassed only 10 years before this engine!

* As of 2018, the PS-90A76 fleet leader had spent up to 14000 hours on-wing without removal for maintenance and the high-time PS-90A had accumulated 44000 hours total - that is not too shabby at all! Sure, individual CFM56s regularly double those figures, but that's exceptional even among Western types. Now that Aeroflot has retired its Il-96s these stats will probably plateau though, these were likely the hardest-run PS-90s and flew the longest routes (so they were busily racking up those hours!). Without operating in a commercial airline environment, I doubt the WS-20 will be able to match this kind of performance for a long time, if ever.
 
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cfchang

Just Hatched
Registered Member
Is this guy drunk? ws-10 a copy of al-31? Excuse me, this is BS.

Similar requirements do not mean copy!

If this guy go checking the latest Chemistry/ Material research papers, he will find out that Chinese chemical scientists are now producing the most papers and the most referred to.

And we all know that the "Blade" is really come down to understanding of chemical and material engineering process.
 

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