Here's a little story that i came up with. It was created by observing the engine deals, chronology of development and so on in Russia and China in the last few decades. While a lot of its content is conjecture, i think there's also a lot of it that sounds quite plausible. Real info is, of course, hard to get. So everyone reading this can make up their minds as to how much of this story is fact, and how much is fiction.
Cold war ended. Saturn, which was developing al31 series of engines as well as producing them with UMPO suddenly found itself without a lot of funding. Salyut, which was just producing al31f, also got itself without much funding.
At the same time, China wanted to modernize its forces. Partly by buying ready products, partly by producing domestic aircraft. Russia was in economic shambles and was desperate for any sort of business. China proposed a few deals which Russia agreed to. One was sale of large amount of al31f, for the su27 that China bought, other was funding of al31fn, a variant of al31f for j10. All that happened in early 1990s.
At the same time, shenyang liming was into full scale development of its ws10 for half a decade. Suddenly, through the al31fn deal, where china financed its whole development, they also bought access to documentation of al-31, possibly even documentation on its production process. At some point, perhaps not right away in 1992 but a bit later, work on a new variant of ws10 started, labeled ws10a. Why shenyang liming stayed with f101 engine core as a basis is unknown, but perhaps too much work was already done with it, and new tech applied from russian producers was seen as enough to finish the ws10 with the core that it already had.
Saturn developed al31fn, and a small preproduction batch of the engine were sent to China to power the j10 prototypes. At the same time, lots of al31f were produced, where both saturn and salyut benefited from it. Saturn used the al31fn money from china to develop not only the said engine, but help develop al31fp for India's Su30. Saturn and Salyut made a deal where Saturn/umpo made engines for india, and Salyut would make engines for china and pay Saturn a provision.
Enter the 2000s. Preproduction of al31fn was done, it was decided salyut would handle the production of serial standard engines. But a spat between saturn and saylut arose. Salyut claimed they had to finish development of al31fn and claimed al31fn as their product. they didn't pay Saturn any royalties from sales. Suddenly there was a big gap in Russian engine producers. Saturn, the big designer and its UMPO cooperant, sponsored by the Russian state, and on the other side the rogue Salyut with relatively scarce resources and very few customers at the time, basically just China.
It is plausible chinese side got a chance for even tighter cooperation with the russian side, but this time directly with Salyut. It provided money and Salyut provided expertise, not only with finishing al31fn and getting it fully ready for j10a, but also with providing assistance with ws10a project.
Of course, such deals are often two way streets. While Saturn was, comparatively speaking, rolling in cash from both Russian state (to develop next gen engine variants) and from lucrative al31fp deals with india and other irkut su30 users, Salyut used the chinese money and work on al31fn variant to further improve al31 family. hence al-31f-m1 finished development around 2006/2007.
Roughly during the same time period, Salyut's work on new al31 variant went into two more projects. One was another subvariant of al31fn, which i'll call "series 2 variant", which was allegedly offered to china in 2006, with 13500 kgf thrust and even thrust vectoring. While we know China didn't go for thrust vectoring addition, we don't know if the engine subariant itself fairly quickly found a way to future j10a built near the end of 2000s and later.
While ws10a allegedly first time flew in 2002., we know it didn't really enter service until the end of that decade. Since Salyut and chinese side enjoyed such good coperation in that period, it is also plausible that not only al31fn work but also work on al31f-m1 actually helped shape ws10a to where it really was once it entered active service on j11b. Anecdotal evidence for that include claims that the engine itself was certified back in 2007., but production quality issues delayed it for a few years. Also, there are claims that russians themselves said ws10a is in the low 130kn thrust class, similar to al31f-m1.
Salyut-Shenyang liming cooperation continued at the end of 2000s and into first half of 2010s. We know bench tests of al31f-m2 were completed in 2012 and flight tests were to commence. Then came news of al-31fn "series 3" engine bench testing in 2013. Evidently, chinese side maintained cooperation and paid for further development all those years. That further makes it more plausible that "series 3" is in fact based on al31f-m2 variant work. official news said "1000 kgf" was added to previous variant, but "series 2" was really never publicized. if news from 2006 about 13500 kgf al31fn variant is true, that plays right into the known 14500 kgf al31f-m2 or hypothetical al31fn series 3 based on it.
At the same time, work on ws10 variants continued. New variant, ws10b, seems to either in production or very near mass production, since a different variant was seen on active duty flankers. if we take into account the fact that ws10a was delayed by quality issues, not the design which was ready some 6 years ago, it is quite plausible another version would be ready in that timeframe. just as salyut went from al31fn to al31f-m1 in 6 or so years, and will take another 7-8 years to m2 variant. While ws10b is likely to contain more domestic input now than russian, and perhaps is not quite up to m2 variant level, it may well be in 135-140 kn range. Since it was not known how that'd turn out, years earlier the decision to pay salyut for al31fn series 3 was made. now the chinese side may find itself in a situation where they have two engines of comparable perfomance to choose from.
Also, while ws15 may be based on a different core, perhaps domestic one, it too is bound to have benefited from all this cooperation. But who knows when it will enter mass production.
Some of this fiction was sourced from here, a page aggreggating some other sources on al31 history. Other stuff was concocted in my head.
