Chinese Engine Development

sunnymaxi

Major
Registered Member
We saw a single piece 3D printed CMC compressor blisk fly on a tiny demonstrator maybe two years ago
that was three years ago

''An integrated blade/rotor assembly. They were bench testing a CMC blisk at X'ian University before they flight tested a CMC blisk on January 1, 2022 in Zhuzhou, Hunan. The flight test was a proof of concept so the real stress testing was all done in the lab''

most probably they have taken more flights for further testing and material validation. its been three years now so we can expect CMC in CJ-2000 Engine as RR's UltraFan has CMC, GE commercial Engines also using this.

AECC official Weibo handle do compare CJ-2000 with similar products globally.
 

latenlazy

Brigadier
It makes me wonder how much something like you'd put on a BYD vehicle as brakes would differ from something you'd use in a turbofan engine. I'm sure the requirements inside turbines would be higher. But this is one area where since it's still a relatively new field, China can get to the front relatively quickly.
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From the limited reading I’ve done on CMCs the quality of the fibers and their specific weave, and the ceramic matrix properties all need to be tailored for the specific application. Crack resistance is a big deal for fan blade applications. I think the primarily question for adoption is part life and durability for high temperature high strain conditions.
 

by78

General
More high-resolution images from Zhuhai.

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interestedseal

Junior Member
Registered Member
From the limited reading I’ve done on CMCs the quality of the fibers and their specific weave, and the ceramic matrix properties all need to be tailored for the specific application. Crack resistance is a big deal for fan blade applications. I think the primarily question for adoption is part life and durability for high temperature high strain conditions.
At least three companies in China are mass producing 3rd gen continuous SiC fiber (this is probably the most restricted/embargoed fiber material in the world).
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Many downstream startups are being founded like fiber 3D weaving tool, AFP tool, SiC/CF fiber 3D printer and water jet cutting/drilling. The whole ecosystem has been created
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interestedseal

Junior Member
Registered Member
Then it's worth going over. Casting is, at its most abstract, is taking a liquid and freezing it into a shape using a mold. The different terms "single crystal casting", "directional solidification" and just "casting" have to do with the atomic structure of the liquid after it freezes. Liquids typically solidify into crystals - a regular lattice of atoms.

When you just cool a liquid below its freezing point, crystals begin to form at different points in the liquid (called nucleation sites). Molecules or atoms from the liquid arrange themselves on the surface of the crystal and the crystal grows outward. Since there are many such crystals, they eventually push up against each other. The surfaces where crystals meet are called grain boundaries. The resulting solid is called "polycrystalline" (many crystals).

In almost every single application, this is nothing to worry about. But turbine blades are in a uniquely challenging environment - high temperature, high pressure, and high centrifugal forces. Grain boundaries in a turbine blade are weaknesses, and eventually the blades warps or cracks or otherwise fails.

With great difficultly, you can cool a liquid so that only one crystal forms and grows. All of the atoms of the liquid attach to that growing crystal and no other forms. This is single crystal casting, and it's what China had so much difficulty with in the past.

A step between just freezing the liquid haphazardly and single crystal casting is directional solidification. This is where multiple crystals form, but they all grow in the same direction parallel to each other. The resulting solid has grain boundaries and they're still weaknesses, but they're less weak than if the crystals grew in a disordered fashion.

All of this is to say

He's talking about something different. What he's referring to are macroscopic defects in the solid. Typically, in 3D printing bubbles and other large defects form in the solid because the melting and cooling from the laser pulses are so rapid that they trap gas. This is what BLT managed to control in their process and the resulting structure is free from such defects.

What I'm asking is if the 3D printed solid has multiple crystals. Grain boundaries aren't macroscopic defects, they're defects at the atomic level. To print a single crystal is far, far harder than printing a polycrystal structure free from cracks or bubbles.
3D printing superalloy single crystals is still experimental. But 3D printed ceramic cores used for investment casting of the single crystal blades are becoming a reality. Making these ceramic cores used to be a very slow process. Here are some Chinese ceramic 3D printer vendors that make ceramic cores for casting hollow single crystal blades.
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by78

General
High-resolution images of turbine generators on display at Zhuhai.

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By the way, the Taihang 15 turbine generator, also known as AGT-15, has recently passed 72-hour continuous operation test.

11月18日,广西涠洲岛燃气轮机电站首台国产“太行15”燃气轮机顺利通过72小时连续运转考核,这标志着“太行15”燃气轮机首次上岛并网发电成功,将有效缓解涠洲岛用电紧张情况。“太行15”燃气轮机由中国航发燃机制造生产,是涠洲岛燃气轮机电站发电机组中的主机。本次72小时连续运转考核累计发电44万kWh,最高功率带载9.5MW。
On November 18, the first domestically produced "Taihang 15" gas turbine at the Weizhou Island Gas Turbine Power Station in Guangxi successfully passed the 72-hour continuous operation test, which marked the first successful grid-connected power generation of the "Taihang 15" gas turbine on the island, which will effectively alleviate the power shortage on Weizhou Island. The "Taihang 15" gas turbine is manufactured by China Aero Engine Gas Turbine and is the main engine of the generator set at the Weizhou Island Gas Turbine Power Station. The 72-hour continuous operation test generated a total of 440,000 kWh of electricity, with a maximum power load of 9.5MW. Subsequently, China Aero Engine Gas Turbine will also put into production one 15MW and one 12MW gas turbine units, with an estimated annual power generation of 350 million kWh.

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