SamuraiBlue
Captain
If I remember correctly Blisk will become the source of the problem for vibration not the cure.
From Wiki;
Chinese Engine Development
- Thread starter jackbh
- Start date
From Wiki;
Could be that it was the cause. I'm pretty sure that solving those issues (which has been shown to be possible elsewhere after all) should be trivial compared to creating hollow composite blades (for which there is no precedent AFAIK) though. In fact, since the first 4 stages of the CJ-1000A HPC are blisks and the first of them should be pretty large (by my reckoning diameter would be approaching 0.6m, not far off the fan diameter of a M88-class engine), solutions appear to exist in China.
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Quickie
Colonel
It's about rigidness. A flexible material contribute to vibration by way of uneven distribution of mass as the material flexes under external forces.
Hendrik_2000
Lieutenant General
That is correct I can tell that in industry you want the natural frequency of the rotating system to be 3 X the frequency of rotating machine. I don't know what it rotation of GT in rpm converted it to herz
The reason is to stay away as much as possible from 1st and 2nd mode of vibration
So the stiffer the system the better it is to resist vibration because you cannot eliminate 100% imperfection even for Japan. It will always be there and high rpm only amplify the problem
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Nope. Definitely says composites fan blades. Blisks is a totally different term, and “composite material” is not synonymous at all with “composite structure” in Chinese. There’s no shorthand “composite” word that has multiple general meanings.
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What I could find on hollow composite fan blades using google search. It’s possible they did something that’s similar to the techniques in one of these patents.
Wrt the vibration problem, my guess is that as new materials and techniques became available they kept aggressively revising the design to push performance, and the vibration problem was something wholly unanticipated which emerged during the process. Rather than rollback to a lower performance version without these problems they made the decision instead to find new solutions to resolve those vibrations while trying to maintain or further improve upon whatever performance gains they attained with the changes that caused the vibration. That’s just a rough hypothesis on my part though.
antiterror13
Brigadier
remember? ... you just tread the wiki and suddenly become an expert
"Remember" is something you knew well in the past and still know a bit now ... hahhaha
In post #4746, the quoted wording was 复合材料叶片 which is Composite Material Blade. There can not be any mistranslation.
Interesting... all I can say is that I'm not holding my breath.
Patents do not equal a hardware precedent - there are countless patents for innovations that are perfectly sound in theory but to which manufacturing and/or materials technology has simply not yet caught up (and sometimes may never do!). Hypersonics is an area which has more than its fair share of such cases.
When you're in a position of chasing after the state of the art, replacing a technology where solutions for the challenges you are encountering are proven to exist with one that is completely novel in practical application is a huge risk. There's always the chance that you'll hit one or more unanticipated issues which are even more difficult to surmount than the original problem you were hoping to outflank.
And continuing to roll new technologies into an ongoing development programme as they become available (feature creep) is a good way of creating a HAL Tejas, if you're not careful.
Patents do not equal a hardware precedent - there are countless patents for innovations that are perfectly sound in theory but to which manufacturing and/or materials technology has simply not yet caught up (and sometimes may never do!). Hypersonics is an area which has more than its fair share of such cases.
When you're in a position of chasing after the state of the art, replacing a technology where solutions for the challenges you are encountering are proven to exist with one that is completely novel in practical application is a huge risk. There's always the chance that you'll hit one or more unanticipated issues which are even more difficult to surmount than the original problem you were hoping to outflank.
And continuing to roll new technologies into an ongoing development programme as they become available (feature creep) is a good way of creating a HAL Tejas, if you're not careful.
¯\_(ツ)_/¯ it’s just speculation on my part. If I’m right though it would mean they're putting the development and expansion their technological capabilities ahead of delivering the specific project, and this may not be the wrong move for them in the long term.