I don’t like this style of posting either, but if any terms to the effect of “next generation low bypass high thrust engine” was actually uttered by Liu I think we can be reasonably sure he was talking about the WS-15.
Chinese Engine Development
- Thread starter jackbh
- Start date
True, I am with you.
SamuraiBlue
Captain
I believe they left out the word "weight" since it is going to be hollow, although I do not think making it hollow has anything with stability.
Vibration within a rotating axis is due to dis-alignment of weight distribution among the fins where one fin is heavier than the one on the opposite side which is suppose to work as a counter balance. Basically this is due to inefficient machinery in creating the fins.
Less weight will reduce the problem but in no way a solution to the problem resulting to less running time between maintenance since the ball barrings are going to run out faster due to the stress.
“Quality” in this case should be translated into mass. The relevant sentences for reference are bolded below:
第二，是我国已经实现了空心复合材料叶片设计及制造，目前某型号涡扇-1XX发动机已经在2021号歼-20原型机上投入测试，这款发动机或已经开始使用空心复合材料叶片技术，采用上述复合材料和工艺的风扇叶片，不但明显减轻了叶片本身的质量，还减轻了其包容环、盘以及整个转子系统的质量，具有成本低、抗振（抗颤振）性能好、抗损伤能力强等特点，在解决涡扇-15整机振动问题上发挥了关键性作用。第三，我国在第二代数字电子控制系统、整体叶环设计、多斜孔发散冷却火焰筒结构、新一代板涡轮盘设计及制造技术、三维推力矢量喷口等一系列先导技术上获得了全面性突破，在2016年解决了整机振动问题之后，涡扇-15型号原型机的设计指标还在原有基础上进行了调整，提高了其整体性能要求，这些都是基于在基础性技术上的集中突破进展上的。
Typically when describing weight reduction the term most often used is 减重, where 重 means weight, but in this case the author used 减质量, or reduce mass, where 质量 means mass. The machine translation seems to have been confused by the use of mass here, since 质量 can also mean “quality”.
The author wasn’t saying that weight reduction reduces vibration, but that the use of composite fan blades reduces vibrations.
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Quickie
Colonel
Thanks for the explanation.
I think the reduced mass and the rigidity of the composite material helps to reduce vibration.
SamuraiBlue
Captain
It's not about rigidness, it's about resonance, composite material with two different material cancels out resonance.
It's what they learned from the Tacoma Narrow bridge accident.
I suspect composite is another mistranslation (like quality/mass) here, actually. It probably refers to a blisk, i.e. BLades Integrated with the diSK into a single piece - a "composite" of blades and disk. This can be done with separately manufactured hollow blades by joining them to the disk via linear friction welding and IIRC is used in the LP compressors of the EJ200, F119 & F135. Composite blades are difficult to make hollow, cannot be integrated with a metal disk and are generally not appropriate for a fighter engine with its small fan diameter. A blisk is generally preferable up to the largest business jet engines (~ 50 inch diameter, like the GE Passport that is based on the LEAP core but lacks the composite fan).
Finalized in next three to five years????
Liu Daxiang, an academician of the Chinese Academy of Engineering, explained the current status of aviation engine development.
On July 7, Liu Dasheng, an academician of the Chinese Academy of Engineering, stated for the first time in a public lecture that China’s fourth-generation military small bypass ratio aero engine project is progressing smoothly and will be finalized in the next three to five years. The media believes that this is the fourth generation of China. Military small bypasses have a clearer report on the progress of the aero engine project for the first time.
After that must be 3 to 5 years again trial in aircraft,
So when will WS-15 be ready to combat? 10 years again??