Kaveri & Aero-Engine: News & Discussion

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Indranil
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Re: Kaveri & aero-engine discussion

Postby Indranil » 27 Mar 2018 01:46

Jay,

These discussions need to be catalogues of future reference. Could you please move the relevant posts to the Kaveri gyan sticky thread.

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Re: Kaveri & aero-engine discussion

Postby JayS » 27 Mar 2018 10:11

Indranil wrote:Jay,

These discussions need to be catalogues of future reference. Could you please move the relevant posts to the Kaveri gyan sticky thread.


Yeah. That's pending from my side. Quite a bit of good posts to move.

ramana wrote:Madhu, Great job.

So Kaveri is underperforming at 1.5KN below specification.

Is that bad enough to can it?
A/B is for take off and get away from dog fight.

And its flat rating should count for something?

JayS, Now we have numbers to discuss, what's the real problem?

Engine weight for the thrust?
With expected weight savings in Tejas should this even out?


Ramana,

of coarse some short fall is not too bad (+/-2% from target is usual). But As such Kaveri is not good enough for LCA now. They need to fly Kaveri so we get acquainted with the certification and full debugging process. So next iterations are faster.

Above numbers do not change any of the assertions we have made here previously. There is nothing wrong as such with the dry thrust, some small changes to bump up efficiencies by 2-3%, reduce leakage etc would be sufficient to bring it quite close to design dry thrust. Efficiencies are on lower side as compared to the competitor engines (we knew it already from specs). A/B needs some work to achieve wet thrust, but its almost independent module from rest of the engine. And this is only one operating point. The engine needs to run in full envelop spanning 0-15km and 0-1.8M at various inlet conditions. The reported problems are related to flutter, vibrations in some flight regimes which will not show up in such calculations obviously. But I have posted one paper from Dec 2017 which shows GTRE has worked out compressor blade flutter issues.

All in all, I think, single biggest thing remaining is A/B design. Other things are small and within grasp. GTRE claimed they figured out A/B issues too but I am yet to see proof other than their word from AI-2017.

Flat rating is obviously a big deal for a fighter. But it puts a lot of constraints on engine design. Designer needs to suppress thrust at low altitudes lower than max possible. What it means is, there is artificial limit of TET at lower altitudes for Kaveri which limits its thrust at lower altitudes. If they remove that limit obviously Kaveri can produce more thrust at SL than rated now. But obviously the damage is not done as the design choice of flat rating forced them to go with lower BPR, so just hiking TET wont still be optimum solution. If they choose to redesign Kaveri, they should let go of flat rating requirement IMO. Why make it unnecessarily complicated. Anyway none of the comparable jets such as F404, M88, RM12 are flat rated.

PS: Do remember that model used by Madhu is still not completely realistic. For example it does not account for Cooling air off take from HPC which can be as high as 30% of HPC output.

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Re: Kaveri & aero-engine discussion

Postby Pratyush » 27 Mar 2018 11:21

A nube question for people who know more than me. This is regarding the choices made by the Tejas program for the Kaveri. When contemporary engine designs were not flat rates. Why did the ASQR specify flat rates engine. Also what are the potential advantages of flat rating. And how it will effect the performance of the Tejas. If and when it is put into service with the flat rated Kaveri.

Sorry, too many questions but only for my understanding.

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Re: Kaveri & aero-engine discussion

Postby jaysimha » 27 Mar 2018 12:21

Found these 2 old articles, Posting for records only.

Flat rating concept introduced in the GTX engine
Arun Prasad and V. Sundararajan
http://publications.drdo.gov.in/ojs/index.php/dsj/article/viewFile/6007/3132

Capacity-building in defence science and technology
A perspective from the DRDO
Suranjan Pal & william selvamurthy
https://www.drdo.gov.in/drdo/English/dpi/2008/IDSA.pdf

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Re: Kaveri & aero-engine discussion

Postby JayS » 27 Mar 2018 12:28

Pratyush wrote:A nube question for people who know more than me. This is regarding the choices made by the Tejas program for the Kaveri. When contemporary engine designs were not flat rates. Why did the ASQR specify flat rates engine. Also what are the potential advantages of flat rating. And how it will effect the performance of the Tejas. If and when it is put into service with the flat rated Kaveri.

Sorry, too many questions but only for my understanding.


Why it was specified..? Our folks have knack for setting up programs for failure from starting. GTRE should not have accepted it as requirement. They should have flatly (pun intended) refused to accept it (or at best kept it as lose constraint) even if ASQR mentioned it.

Advantage is you have the exact same thrust that you get on the ground till certain altitude, say 10000ft. A non-flat rated Kaveri would have given 84kN at Sea Level and thrust would go on reducing with increasing altitude. With flat rating it would continue to give 84kN thrust upto certain altitude and only then you would have reduction in thrust. In simple terms available thrust while flying at altitude would be more with flat rating than with non flat rating. (e.g. LCA could supercruise with Kaveri if Kaveri achieved design thrust levels while with F404 it wouldn't). Operational ceiling of aircraft would also increase effectively. The engine would be much better under hot and high and hot conditions which we see in Laddakh. That's why Kaveri design is more challenging than F404 as it has all design targets same as F404, with lower technology at hand and with stricter design goals.

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Re: Kaveri & aero-engine discussion

Postby Aditya_V » 27 Mar 2018 12:41

So we asked for soemthing from the size of the F404 which GE with so many years of design experience could not deliver. Wow.

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Re: Kaveri & aero-engine discussion

Postby Pratyush » 27 Mar 2018 13:17

Now I am beginning to understand the 3 legged cheetah remark.

As the engine is inferior to what it was intended to fly with.

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Re: Kaveri & aero-engine discussion

Postby madhu » 27 Mar 2018 18:30

JayS wrote:PS: Do remember that model used by Madhu is still not completely realistic. For example it does not account for Cooling air off take from HPC which can be as high as 30% of HPC output.

To do that kind of analysis I need much more data. I think I need to do stage by stage analysis and find efficiency loop it back to cross check.
If we start going into that level, I guess we need to do full mean line design right? Like number of stages, number of blades, blade inlet and outlet angle at mean radius, combustor performance and over all dimension. There are too many variables to choose from.
Do you any clue how to go about it?

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Re: Kaveri & aero-engine discussion

Postby JayS » 27 Mar 2018 23:37

madhu wrote:
JayS wrote:PS: Do remember that model used by Madhu is still not completely realistic. For example it does not account for Cooling air off take from HPC which can be as high as 30% of HPC output.

To do that kind of analysis I need much more data. I think I need to do stage by stage analysis and find efficiency loop it back to cross check.
If we start going into that level, I guess we need to do full mean line design right? Like number of stages, number of blades, blade inlet and outlet angle at mean radius, combustor performance and over all dimension. There are too many variables to choose from.
Do you any clue how to go about it?


Ypu can also do it, nothing great in it. I have once prepared such excel for Civil Jet engine design as assignment in college. It was CF6 IIRC. The spreadsheet was quite large. It had stage by stage thermodynamic design and blade design parameters. Took me two A3 size papers to print it all. It didnt have cooling and offtake, but it can be added. All one needs to do is go from first principle just like the set of equations you used are derived (they are from Mattingly's book right..?) and use simple models for various phenomena. I lack motivation and time, else I wanted to make such python based SW like 3yrs ago. It would have included even the blade airfoil design based on MCA profiles. But it never happened.

But you can add cooling in your sheet, relatively easily. Split the Turbine process between HPT and LPT. Station 4-45 and 45-5. Take say 10% air from HPC output and add in LPT, bypassing Combustor and HPT. That NAL paper link I gave you does this all.

Also there is huge amount of the data/ info you would need for such non-professional level work, is available on internet. You need to know where to look for and what to look for. Obviously not much wpuld be available on operational engines. Browse through older NASA funded engine program related docs from 70s n 80s. There is so much info available that you couldnt even skim through it all.

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Re: Kaveri & aero-engine discussion

Postby madhu » 27 Mar 2018 23:49

Jays,
Right now i am doing it for Civil Jet engine just to calibrate my calculations. But i see that there are too many options to choose from. To do s reverse engineering. I might need data like hub/tip radius etc.
The option are so many that it difficult without cross check every time.
Let me see. Will try for trent 500 and if successful will try and do it for Kaveri

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Re: Kaveri & aero-engine discussion

Postby ramana » 29 Mar 2018 19:13

Jay s and Madhu,
Why dont you meet over a jug of coffee and work this? Take laptop and steno pad for notes. Say 3 months?

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Re: Kaveri & aero-engine discussion

Postby ramana » 29 Mar 2018 19:20

Jays
So flat rating would mean fuel consumption would be higher then without it? Like pushing accelerator all the time to get that constant thrust from SL to altitude.

I think flat rating was thrown as a challenge and has now become a hard requirement.

If all those engines front have it is it fair to demand at first attempt of a Indian turbofan? And they are acceptable without flat rating!

Pratyush, incorrect. Motivated comment.

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Re: Kaveri & aero-engine discussion

Postby Picklu » 29 Mar 2018 19:34

IIRC, N3 recommended to throw out flat rating at least 10 years back. No point to shackle a powerful beast at lower altitude to ensure thrust remains same at the higher.

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Re: Kaveri & aero-engine discussion

Postby ramana » 29 Mar 2018 19:53

We need to find out how flat rating became a requirement instead of a goal.
It's a huge handicap as air density goes down with altitude and to maintain thrust more fuel has to be burnt.

Do we know how this came about?

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Re: Kaveri & aero-engine discussion

Postby Avarachan » 30 Mar 2018 06:40

JayS wrote:That's why Kaveri design is more challenging than F404 as it has all design targets same as F404, with lower technology at hand and with stricter design goals.


Aditya_V wrote:So we asked for soemthing from the size of the F404 which GE with so many years of design experience could not deliver. Wow.


My jaw just hit the floor.

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Re: Kaveri & aero-engine discussion

Postby ramana » 30 Mar 2018 09:28

Live and learn.
Would you never have found that anywhere else!

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Re: Kaveri & aero-engine discussion

Postby ramana » 30 Mar 2018 09:30

Normally flat rating would be a stretch goal and not requirement for a first Turbofan.
GTRE never protested.
They wanted the job.
Now the folks who put that requirement are not there. But it's cast in stone.

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Re: Kaveri & aero-engine discussion

Postby chetak » 30 Mar 2018 10:51

Avarachan wrote:
JayS wrote:That's why Kaveri design is more challenging than F404 as it has all design targets same as F404, with lower technology at hand and with stricter design goals.


Aditya_V wrote:So we asked for soemthing from the size of the F404 which GE with so many years of design experience could not deliver. Wow.


My jaw just hit the floor.


The DRDO went into the kaveri project with nil experience as well as nil exposure but starry eyed and with both eyes shut wide. That they miserably failed to evaluate the enormity of the task is only now hitting home with a vengeance.

Customer requirements would have been discussed threadbare, if only to situate the customer as well as the developers on the same page and prevent later misunderstandings/misinterpretations.

The customer has every right to ask for the moon and he surely will but it is the developer who has to provide the grounding in reality for the project and clearly state what is or isn't within the realm of reality and what is achievable, keeping in mind the technology/talent available.

Nobody has forced anybody's hand.

The customer and the developer may have had options that they did not or chose not to exercise, like maybe direct imports and JV collaborations, only the true insiders can say

Even big and accomplished technological powers like the US, UK, France, Germany, Russia et al, would, even today, balk at the ab initio development of a military jet engine for a single engined fighter application.

Ceteris paribus, it is the enormous ginormous requirement of funds that would give them very good reason to pause and take a long and serious look at such a project.

But in our case specifically, Ceteris paribus or "all other things being equal" simply does not apply. We neither have the scientific talent, technological/infrastructure wherewithal nor the capability of deploying ginormous funds.

I know that folks here will not like my saying so but it is high time that we faced up to the facts on the ground. We are now actively seeking some sort of JV tieups, transfer of core technology and god only knows what else.

This to me, clearly says that we are simply lacking in these areas and the situation extant has no in house or even in country talent/solutions. It is also a fact that such talent/solutions has not existed in India, even from times before the kick off of the Kaveri project and sadly, nor do they exist even now.

This should have been recognized right at the outset, both by the customer as well as the developer. But as Indians, we have always liked to fool ourselves that Indian jugaad will always triumph in the end.

In most cases, jugaad has simply never paid off.

We have now been abandoned mid project, left at the baleful, blackmailing mercy of such greedy and voracious technological powers and are now being made to pay through the nose for mistakes wilfully committed many decades ago by people who surely knew whats what even then but purposely kept very very quiet. I speak to the old timers at various gatherings. This has also happened in many other projects.

I would hesitate to even venture a guess as to what the future holds for us, as far as Kaveri goes.

Let us wait and see how things play out.

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Re: Kaveri & aero-engine discussion

Postby JayS » 30 Mar 2018 11:17

chetak wrote:
The DRDO went into the kaveri project with nil experience as well as nil exposure but starry eyed and with both eyes shut wide. That they miserably failed to evaluate the enormity of the task is only now hitting home with a vengeance.


Its not entirely true that Kaveri was ab initio development. GTRE had at least one (and perhaps more) GT developed before Kaveri. Though the experience was limited, it doesn't take whole lot of genius and experience to know what kind of design goals are achievable for given technological level at preliminary design stage for a Jet engine. Perhaps they knew the enormity and thought they can surmount the challenge, just as LCA team thought about full digital FCS. Sadly for them project Kaveri did not receive commensurate support from government. LCA fared better in that respect. There are some mind boggling things that GTRE has done, and it would be interesting to know rationale behind them. One being Flat rating. Another being - Project Kaveri did not have provision for flight testing in it, or it as a mile stone. They included this step only in mid-late 2000s it seems.

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Re: Kaveri & aero-engine discussion

Postby hanumadu » 30 Mar 2018 11:29

They should have realised that flat rating is not achievable and started working on a new engine with lessons learnt from Kaveri at least 7-8 years ago.

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Re: Kaveri & aero-engine discussion

Postby Aditya_V » 30 Mar 2018 11:34

I don't think DRDO had a choice, the import lobby had set impossible requirements. Foreign countries don't us to have MIC and children Visa and education is a huge carrot no one can run away from. A serving General was Threatened int his country by TATRA.

Wow in the name of performance things like flat rating were slipped in.

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Re: Kaveri & aero-engine discussion

Postby JayS » 30 Mar 2018 11:40

ramana wrote:Jays
So flat rating would mean fuel consumption would be higher then without it? Like pushing accelerator all the time to get that constant thrust from SL to altitude.

I think flat rating was thrown as a challenge and has now become a hard requirement.

If all those engines front have it is it fair to demand at first attempt of a Indian turbofan? And they are acceptable without flat rating!

Pratyush, incorrect. Motivated comment.


You actually limit TET from going to max on ground and lower altitudes to keep thrust artificially lower than what is possible. (that means lower fuel consumption to some extent but then you are forced to use lower BPR so some disadvantage there. Its complicated enough that we cannot make generic statement. One would need parametric analysis of the engine to see overall impact). What flat rating means is that you design the engine to give 54kN thrust at say 10000ft rather than designing it for 54kN on ground. (getting same thrust on ground is easier than at altitude, so in that sense its harder to design or overdesigned). So you are overdesigning the engine so it can still give same thrust at altitude that it gives at ground. Had Kaveri been designed without flat rating it would give 54kN thrust on ground and may be say 45kN at 10000ft altitude. Now it is designed to give 54kN at 10000ft and suppressed to keep it at 54kN on ground by limiting TET, when it could perhaps give 65kN on ground by removing limiter on the TET.

There are quite a bit of benefits of flat rating which make it a very attractive preposition - your fighter has much better thrust available at altitude. You can perhaps even supercruise. You have somewhat better life for HPT components since they run at lower than max temp on ground. You could perhaps even trade off some of the saving in life to hike max TET at altitude to extract slightly higher thrust. You can definitely do stuff and it gives a significant edge to your fighter. But then it also makes you work hard.

Do read the paper linked by Jaysimha above - it explains Flat rating concept used in Kaveri.

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Re: Kaveri & aero-engine discussion

Postby JayS » 30 Mar 2018 11:43

Folks, first of all, we do not know whether flat rating was imposed condition by ASQR or whether it was self-imposed goal by GTRE. Lets keep that in mind while commenting. I am personally only interested in knowing the rationale behind it as of now, not debating it.

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Re: Kaveri & aero-engine discussion

Postby madhu » 30 Mar 2018 17:14

JayS,
I am seeing way too many unknowns to proceed further. if you have any pointers can you suggest? also please PM your mail id so that we can discuss more.

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Re: Kaveri & aero-engine discussion

Postby chetak » 30 Mar 2018 18:11

JayS wrote:
chetak wrote:
The DRDO went into the kaveri project with nil experience as well as nil exposure but starry eyed and with both eyes shut wide. That they miserably failed to evaluate the enormity of the task is only now hitting home with a vengeance.


Its not entirely true that Kaveri was ab initio development. GTRE had at least one (and perhaps more) GT developed before Kaveri. Though the experience was limited, it doesn't take whole lot of genius and experience to know what kind of design goals are achievable for given technological level at preliminary design stage for a Jet engine. Perhaps they knew the enormity and thought they can surmount the challenge, just as LCA team thought about full digital FCS. Sadly for them project Kaveri did not receive commensurate support from government. LCA fared better in that respect. There are some mind boggling things that GTRE has done, and it would be interesting to know rationale behind them. One being Flat rating. Another being - Project Kaveri did not have provision for flight testing in it, or it as a mile stone. They included this step only in mid-late 2000s it seems.


Not arguing but Kaveri was about as ab initio as one can get.

Like running a kindergarten three legged race and using that experience to enter the Olympics.

Considering the existing resources at the time, namely intellectual, infrastructural as well as financial, it was an impossible task right from the minute it was taken up. This is hindsight 20/20 kicking in.

People should have been more careful, realistic and mindful of the expected results and the promised timelines.

After all, this critical national project was feeding through into another highly visible, vital and critical national project.

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Re: Kaveri & aero-engine discussion

Postby hanumadu » 30 Mar 2018 18:22

Using the Kaveri experience, how long will it take to develop a new engine with Kaveri specifications but without flat rating?

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Re: Kaveri & aero-engine discussion

Postby chetak » 30 Mar 2018 18:51

hanumadu wrote:Using the Kaveri experience, how long will it take to develop a new engine with Kaveri specifications but without flat rating?



For the Kaveri, flat rating is the least of the problems.

If other performance and weight and life criteria are met, the customer would probably accept it.

Flat rating can come later.

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Re: Kaveri & aero-engine discussion

Postby Singha » 30 Mar 2018 19:40

we did however manage to develop nuclear weapons and strategic missiles with no help from any of the P5.

but engines have so many facets it was important to control risk & requirements in phases which was not done.

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Re: Kaveri & aero-engine discussion

Postby chetak » 30 Mar 2018 20:29

Singha wrote:we did however manage to develop nuclear weapons and strategic missiles with no help from any of the P5.

but engines have so many facets it was important to control risk & requirements in phases which was not done.



The DAE and ISRO are very different kettles of fish.

need to get rid of DRDO baboo(n)s first.

They have very few genuine scientists.

Simply qualifying some entrance exam and training for many months is no way to become a scientist. It needs passion, dedication and a very different type of intellect. I have been lucky to have met maybe two or three genuine "scientists" so far. It is a real thrill to interact with such towering visionaries. The rest are simply politically aware baboo(n)s who know where the ladder is, how to climb it and which butt to kiss.

Sorry to be so blunt.

This Kaveri thread is the most depressing thing I have read in a long time. It breaks my heart to see the mess that has been created.

Everybody on this thread is sooooo diplomatic and correct. We need many more visionary domain experts/sub matter specialists and not guys who are only experienced in office politics with a mere smattering of subject matter jargon and slick willies who know which sauce goes best with which samosa.

DRDO is currently training a lot young opportunists with one eye permanently peeled for employment in foreign private companies.


Twitter

One of the reason ISRO outperforms compared to any other GoI departments is due to the fact that Scientists are given free hand to formulate their own policies/goals with their domain expertise.


Bureaucrats are making a mess of everything and anything they have control over yet they remain on commanding height. This is the tragedy of this country since the British created this relic in the nineteenth century to further their colonial interests.

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Re: Kaveri & aero-engine discussion

Postby chetak » 30 Mar 2018 21:08

Singha wrote:we did however manage to develop nuclear weapons and strategic missiles with no help from any of the P5.

but engines have so many facets it was important to control risk & requirements in phases which was not done.


Are warheads and their delivery systems any less complicated, saar??

And yet we mastered it.

Imagine the systems and their reliability, they have to operate at optimum level after years of storage and being roughly jostled about from place to place.

And yes, I am aware that these machines are one shot affairs and aero engines are daily use machines and have to perform equally reliably, sometimes over decades of use/misuse.

How and why did some groups succeed while some others did not??

We need to look inward and honestly introspect.

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Re: Kaveri & aero-engine discussion

Postby madhu » 30 Mar 2018 23:02

chetak wrote:We need to look inward and honestly introspect.


Sir each technology have its own complexity but jet engine is more complex than nuclear technology. Imagine u need to maintain a candle flame while you are driving at 500kmph. Thatz what happens inside GT. The air is at 0.3~0.5 Mach and u need to sustain combustion. Temperature that turbine guide vane sees is 1900C where as the melting point of inco/Ti is around 1300~1500C yet u need to make it work without melting.

Topping all these we can buy jet engine off the shelf but we cant do the same for nuclear weapons. So politicians are reluctant to fund engine programs.

Please note we do not have IC engine still. Coz thats not priority so is jet engine for government.

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Re: Kaveri & aero-engine discussion

Postby Neshant » 30 Mar 2018 23:34

Modelling the vortices in jet engines

Supersonic jet physics is hellishly complicated, but Chinese researchers are making gains in understanding it. Andrew Masterson reports.

https://cosmosmagazine.com/physics/mode ... et-engines

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Re: Kaveri & aero-engine discussion

Postby chetak » 30 Mar 2018 23:54

madhu wrote:
chetak wrote:We need to look inward and honestly introspect.


Sir each technology have its own complexity but jet engine is more complex than nuclear technology. Imagine u need to maintain a candle flame while you are driving at 500kmph. Thatz what happens inside GT. The air is at 0.3~0.5 Mach and u need to sustain combustion. Temperature that turbine guide vane sees is 1900C where as the melting point of inco/Ti is around 1300~1500C yet u need to make it work without melting.

Topping all these we can buy jet engine off the shelf but we cant do the same for nuclear weapons. So politicians are reluctant to fund engine programs.

Please note we do not have IC engine still. Coz thats not priority so is jet engine for government.


madhu ji,

And we have also built nuclear subs, the most complex of all complex weapon systems, bar none.

why do some organizations succeed while some others do not, is still the key question, no??

BTW, thanks for the lesson on aero engines.

Over the long years, I have handled more aero engines/marine GTs, both military and civil and from varied sources, than you could probably shake a stick at. :)

I really hope that something worthwhile emerges from the Kaveri project. I understand that folks are really pulling out all the stops.

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Re: Kaveri & aero-engine discussion

Postby Indranil » 31 Mar 2018 00:13


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Re: Kaveri & aero-engine discussion

Postby Haridas » 31 Mar 2018 12:28

madhu wrote:
chetak wrote:We need to look inward and honestly introspect.


Sir each technology have its own complexity but jet engine is more complex than nuclear technology. Imagine u need to maintain a candle flame while you are driving at 500kmph. Thatz what happens inside GT. The air is at 0.3~0.5 Mach and u need to sustain combustion. Temperature that turbine guide vane sees is 1900C where as the melting point of inco/Ti is around 1300~1500C yet u need to make it work without melting.

Topping all these we can buy jet engine off the shelf but we cant do the same for nuclear weapons. So politicians are reluctant to fund engine programs.

Please note we do not have IC engine still. Coz thats not priority so is jet engine for government.

Speed may be 0.5 mach, but the temperature & pressure is also very high, so combustion rate is easy and good. So it's a metaphor.

Otoh Thermonuclear fusion is a more realistic comparision to lighting wet wood in typhoon with one dry matchstick.

hanumadu
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Re: Kaveri & aero-engine discussion

Postby hanumadu » 31 Mar 2018 13:41

chetak wrote:
hanumadu wrote:Using the Kaveri experience, how long will it take to develop a new engine with Kaveri specifications but without flat rating?



For the Kaveri, flat rating is the least of the problems.

If other performance and weight and life criteria are met, the customer would probably accept it.

Flat rating can come later.


From the discussion before, flat rating seems to be problem. The design decisions made for flat rating are making it difficult to achieve the required performance.

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Re: Kaveri & aero-engine discussion

Postby Neshant » 01 Apr 2018 04:15

Haridas wrote:Otoh Thermonuclear fusion is a more realistic comparision to lighting wet wood in typhoon with one dry matchstick.


Not to side tack the thread but basic fission nukes are 1940s technology. Fusion nukes are early 50s.

I would think it's a lot easier to build a fusion nuke than a high performance fighter jet engine.

It's also the reason passenger airliners have engines from just 3 global manufacturers - GE, Pratt & Whitney, Rolls Royce.

Although China will muscle in on that cartel soon enough.

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Re: Kaveri & aero-engine discussion

Postby pravula » 01 Apr 2018 07:12

Neshant wrote:
Haridas wrote:Otoh Thermonuclear fusion is a more realistic comparision to lighting wet wood in typhoon with one dry matchstick.


Not to side tack the thread but basic fission nukes are 1940s technology. Fusion nukes are early 50s.


And jet technology is which decade? 1920s?

Neshant
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Re: Kaveri & aero-engine discussion

Postby Neshant » 01 Apr 2018 07:58

pravula wrote:And jet technology is which decade? 1920s?


Modern jet technology is way more advanced than when first invented.
It's well beyond producing a big bang.
A 70s nuke would provide just as much deterrence as a present day nuke.
It's mostly advances in the delivery system that has changed, not the nuke itself.

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Re: Kaveri & aero-engine discussion

Postby saumitra_j » 01 Apr 2018 07:59

hanumadu wrote:
chetak wrote:

For the Kaveri, flat rating is the least of the problems.

If other performance and weight and life criteria are met, the customer would probably accept it.

Flat rating can come later.


From the discussion before, flat rating seems to be problem. The design decisions made for flat rating are making it difficult to achieve the required performance.

Not sure about that - from what I understand, the biggest problems for Kaveri are timelines (it is already TOO late) and being overweight. Nobody among the powers that be are convinced that giving additional time to the program will result in something useful in meaningful time. Unfortunately, that is the perception and regardless of how much we talk about lack of testing facilities, lack of budget et al, this perception problem is difficult to solve IMHO. To give some perspective, as of AI 15, Kaveri had done just about 3K or 4k (don't recall the exact no) hours of ground run. It needed to do much more before it could move for a double engined aircraft for testing and a 1000 or so hours more before it was allowed on a single engine aircraft. The second problem is simply about materials - Kaveri is overweight - so even if the previous problem is solved, the materials problem will always result in less than required TWR. Given the operational requirements and need to develop technology, the GoI is doing its best through the Kaveri Snecma route - hopefully the Rafale deal will help address some of the infrastructure issues around GT development and the Kaveri Snecma venture will provide the right kind of experience and confidence to our institutions to develop a GT that will power our aircrafts!


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