Aircraft engine problems continue to surface in China, which are planned to be used on the fifth generation fighters J-20 and J-31. We are talking about power plants WS-15. If in November 2019 years in the Chinese media began to publish publications, which claimed a "breakthrough" in the creation of these engines, then the informational cheerfulness in this regard faded somewhat.
cause, as it turns out, is the unresolved problem of a sharp decrease in the thrust of the WS-15 engine when the temperature of the turbine of the power plant approaches the operating parameters. When the temperature indicator is exceeded in 1350 degrees Celsius, the engine has a loss of thrust, and initially the loss reached 25 percent, what, for obvious reasons, unacceptable for fighters, claiming high maneuverability. Finally, this is just dangerous when flying, because the pilot can lose control of the fighter.
Recently, the loss of thrust at the exit of the turbine to the indicator of operating temperatures, managed to reduce to about 18%. However, the Chinese engine builders have not yet been able to completely get rid of this problem.. It is believed, that one of the problems is related to the used alloy, the optimal composition of which we tried to find several times, changing the original options. Another problem is the accumulation of fuel in the engine without its timely combustion..
In this regard, China does not hide the fact, that the demonstration of the fifth generation Su-57 fighters with engines of the so-called second stage is expected in Russia. We are talking about "Product 30" – by-pass turbojet engine with afterburner. Fuel ignition, as described in open sources, in a Russian engine it is carried out directly when it enters the combustion chamber, equipped with a plasma ignition system with installation on injectors. This avoids various options for inefficient fuel combustion., which, as in the same Chinese, led to a final loss of traction. At the same time, in the Russian engine of the second stage, the operating temperature of the gases reaches 1800 degrees Celsius, and afterburner thrust - 18 tonnes.
Technology is clearly important for China, which is used by Russian engine builders, and therefore there is a possibility that, that the PRC will nevertheless decide in the end to order a limited batch of Su-57 with engines, developed under the "Product 30" program. In this way, WS-15 thrust loss issues force China to pay particular attention to Stage 2 engines for Russian fighters.
Chinese military experts point out, that such a variant of the import of the Su-57 would be acceptable. This is how Chinese engine technology is forged…