Kaveri & aero-engine discussion

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hanumadu
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Re: Kaveri & aero-engine discussion

Postby hanumadu » 28 Feb 2018 23:54

madhu wrote:
JayS wrote:What are the gaps remaining still for Kaveri to reach finish line. As far as I figure out two main issues are there - one is flutter in Fan blades at certain flight regimes and second is sub-optimal functioning of A/B. Can you confirm if this is correct assessment or there's more to it..?

The major problems of flutter induced vibration of fan and initial compressor blades were fixed. In fact due to pattern factor combustor LP turbine blades were getting excitied to torsional mode. He told all these were fixed. The issue are meeting the dry thrust and thrust with A/B. currently with out A/B is still around 47 kN( ~8% short) and Full afterburner ~76 kN ( not sure) or so…
He told this can be achieved by pluged the leak and other small redesign to increase. He feels another 5% ( in short fall of current 8%) can be done with ease but reaching 100% thrust will be tough.


The dry thrust and wet thrust figures are from 5 years ago or may be more. The screech and vibrations are fixed is good news.

Indian establishment does not want to let out the state of various projects especially the strategic ones.
The vibrations and AB problems were fixed in 2000 but they were given wide publicity only recently with defence journalists reporting they are yet to be fixed.

Another example is Tejas Mk2 status. All news was of how not work is being done on it and it is shelved but Saurav Jha recently tweeted much work was done on it and a prototype can be developed in 2-3 years if funded.

I take all news on our strategic programs as something that the establishment wants us to know rather than what the actual state is.

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Re: Kaveri & aero-engine discussion

Postby madhu » 01 Mar 2018 07:55

ramana wrote:Madhu, Thanks. So it's the Kabini core that's good and rest have to be rejigged.
Can we ask you questions once in a while for you to run it by him?
That way we have a way to get gnan like Ekalavya?


sorry ramman. its just that i was in a course learning about design and analysis of Jet engines where he had come to lecture i happened to meet him.

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Re: Kaveri & aero-engine discussion

Postby madhu » 01 Mar 2018 08:01

maitya wrote:Ok, so here it is ... a simplistic (yes, I must admit almost embarrassingly simplistic) side-by-side comparison of this so-called Kaver-with-M88-core, original Kaveri and “paper-injin” called “Improved Kaveri”.
(and no I can’t use Ganga, as it is copyrighted by Vinaji).

Image


i see that you have done calculations based on static thermodynamic points. i have seen performance engineer doing this based on stagnation points. what difference will it make?

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Re: Kaveri & aero-engine discussion

Postby Avarachan » 01 Mar 2018 08:07

JayS wrote:I am quoting my old posts from AI-17 time in current context.

viewtopic.php?f=3&t=3351&start=3040#p2119110
JayS wrote:
I am told 54kN/81kN thrust is achieved. I specifically asked for wet thrust against since we know there was shortfall there. But GTRE folks were insisting that they have achieved 81kN now. Both the compressor flutter and screech issues are resolved now, if you believe them.

SCB is GTRE+DMRL project. SCB with 2nd Gen alloys process is matured tech now, Industrialization of the process is remaining. Apart from making raw blades two more key things lacking are final machining of the SCB's and TBC. MIDHANI is working on this. And they are confident they can do it in 2-3yrs. Right now the blades are to be sent abroad for one or both of these two processes anyway, which is not desirable.

If you notice, Kaveri is running with max 1700K TET value. Currently its not using any SCBs, only DS blades, as per GTRE folks. There is a gap of ~200K here from the state-of-the-art.


viewtopic.php?f=3&t=3351&start=3040#p2119152
JayS wrote:
Its know from public sources those two problems where uncovered. Interestingly a guy from GTRE manning the stall told me they are paying Russians just so they wouldn't share the mods GTRE did to remove those issues. Now how much one wants to buy into this is up to oneself. :)

Snecma claims 1850K TET for M88. So just by porting that HPT tech they can boost TET by 150K..!!

But my guess is they will not do much technical changes in the engine itself, if what GTRE says is true. The said 25% remaining work to make it flightworthy is majority flight testing only without much HW changes. Even if we get flight testing know-how and facilities set up with Snecma's help that itself would be significant for us. We already know Kabini core is working well. It was only the issue with LP system and AB. If those two things are solved then there's nothing really remained in Kaveri to do. Just fly it and certify. Other changes can be done in next iteration.

Also, Kaveri Marine project is not going anywhere since Navy changed the requirements. Now they want next gen specs, I am told.


JayS (or some other guru), could you write a brief article on the background and current status of the Kaveri project? I'm sure there will be lots of nonsense published trashing GTRE ("failure lab," etc.) over the next few weeks. It would be nice if BRF could publish a counter.

Saurav Jha, whom I respect, published an article on the current status in April 2017.
http://www.delhidefencereview.com/2017/ ... et-engine/
But, if your sources are correct, his article is not completely accurate.

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Re: Kaveri & aero-engine discussion

Postby madhu » 01 Mar 2018 08:29

Avarachan wrote:
JayS wrote:I am quoting my old posts from AI-17 time in current context.

viewtopic.php?f=3&t=3351&start=3040#p2119110


viewtopic.php?f=3&t=3351&start=3040#p2119152


JayS (or some other guru), could you write a brief article on the background and current status of the Kaveri project? I'm sure there will be lots of nonsense published trashing GTRE ("failure lab," etc.) over the next few weeks. It would be nice if BRF could publish a counter.

Saurav Jha, whom I respect, published an article on the current status in April 2017.
http://www.delhidefencereview.com/2017/ ... et-engine/
But, if your sources are correct, his article is not completely accurate.

Reheat oscillations is still a problem.

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Re: Kaveri & aero-engine discussion

Postby JayS » 01 Mar 2018 13:21

Avarachan wrote:
JayS wrote:I am quoting my old posts from AI-17 time in current context.

viewtopic.php?f=3&t=3351&start=3040#p2119110


viewtopic.php?f=3&t=3351&start=3040#p2119152


JayS (or some other guru), could you write a brief article on the background and current status of the Kaveri project? I'm sure there will be lots of nonsense published trashing GTRE ("failure lab," etc.) over the next few weeks. It would be nice if BRF could publish a counter.

Saurav Jha, whom I respect, published an article on the current status in April 2017.
http://www.delhidefencereview.com/2017/ ... et-engine/
But, if your sources are correct, his article is not completely accurate.


Unfortunately I do not have time at hand currently, but I can summarize things in one post sometime soon.

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Re: Kaveri & aero-engine discussion

Postby JayS » 01 Mar 2018 13:53

madhu wrote:
Avarachan wrote:
JayS (or some other guru), could you write a brief article on the background and current status of the Kaveri project? I'm sure there will be lots of nonsense published trashing GTRE ("failure lab," etc.) over the next few weeks. It would be nice if BRF could publish a counter.

Saurav Jha, whom I respect, published an article on the current status in April 2017.
http://www.delhidefencereview.com/2017/ ... et-engine/
But, if your sources are correct, his article is not completely accurate.

Reheat oscillations is still a problem.


Madhu, just to avoid misinterpretation, please confirm whether following points are correct or not, based on your recent interaction. Just a final check for me to store the broad points in my mind as correct. I will soon forget details.

1. The short fall in achieved dry thrust by Kaveri is in single digit percentage (8% as you mentioned, I have seen 3-4% in some other place, but still single digit).
2. The demonstrated wet thrust is somewhere between 72-76kN, various values I have seen so far.

Though GTRE claimed in AI-17 they achieved 52kN54kN/81kN we do not have independent verification so far. So lets keep it on hold.

3. One key issue with LPC was blade flutter which is resolved now.
4. LPT blade issue which I was not aware of previously is also resolved.
5. Issue with A/B clearly still persists. Reheat oscillations remains for A/B. Issue of screech was resolved as per GTRE's claim in AI-17, but again we lack verification.
6. The shortfall in Dry thrust can be bridged by some more work to some extent, but not fully.
7. The shortfall in Wet thrust is critically hampered by A/B performance and is unlikely to go away without significant improvement on A/B.
8. The way forward has always been "Kaveri core + modification of LP/A-B system with the help of foreign OEM" and that is still going to be the way forward. IOW, no core borrowing from any other engine.
9. French help is to bridge the gap mentioned in points 6 and 7 and help in flight testing.

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Re: Kaveri & aero-engine discussion

Postby JayS » 01 Mar 2018 13:55

hanumadu wrote:
madhu wrote:
The major problems of flutter induced vibration of fan and initial compressor blades were fixed. In fact due to pattern factor combustor LP turbine blades were getting excitied to torsional mode. He told all these were fixed. The issue are meeting the dry thrust and thrust with A/B. currently with out A/B is still around 47 kN( ~8% short) and Full afterburner ~76 kN ( not sure) or so…
He told this can be achieved by pluged the leak and other small redesign to increase. He feels another 5% ( in short fall of current 8%) can be done with ease but reaching 100% thrust will be tough.


The dry thrust and wet thrust figures are from 5 years ago or may be more. The screech and vibrations are fixed is good news.

Indian establishment does not want to let out the state of various projects especially the strategic ones.
The vibrations and AB problems were fixed in 2000 but they were given wide publicity only recently with defence journalists reporting they are yet to be fixed.

Another example is Tejas Mk2 status. All news was of how not work is being done on it and it is shelved but Saurav Jha recently tweeted much work was done on it and a prototype can be developed in 2-3 years if funded.

I take all news on our strategic programs as something that the establishment wants us to know rather than what the actual state is.

I think you misunderstood, that the problems were fixed in 2000. They were not. Some of these problems were only uncovered in flight testing done in Russian much later (was it 2012..?).

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Re: Kaveri & aero-engine discussion

Postby Avarachan » 01 Mar 2018 20:56

JayS wrote:Though GTRE claimed in AI-17 they achieved 52kN/81kN we do not have independent verification so far. So lets keep it on hold.


JayS, is this a typo? In your original post about AI-17, you said that GTRE claimed *54*/81.

If it was a typo, would you mind correcting your post? I greatly appreciate your efforts, by the way.

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Re: Kaveri & aero-engine discussion

Postby JayS » 01 Mar 2018 21:03

Avarachan wrote:
JayS wrote:Though GTRE claimed in AI-17 they achieved 52kN/81kN we do not have independent verification so far. So lets keep it on hold.


JayS, is this a typo? In your original post about AI-17, you said that GTRE claimed *54*/81.

If it was a typo, would you mind correcting your post? I greatly appreciate your efforts, by the way.


Done. There are multiple numbers from 47-54 that I have come across over the time. Its easy for things to get mishmashed in my head. Likewise for wet thrust.

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Re: Kaveri & aero-engine discussion

Postby habal » 01 Mar 2018 21:47

So basically we (gtre) already have developed an engine core which is of the level of RD-33, only AB and LP need time to make improvements and productionize.

kabini core can be enveloped by M88 LP + AB to give 90 KN (optimistic) wet thrust while M88 core + safran:gtre JV improved AB+LP+shell give 120 KN thrust engine for pv4 rafale, & Su-30 application. This much is the gist of affairs so far isn't it.

Time taken to productionize will also be as long as time taken to develop the kabini core as chinese are experiencing currently.

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Re: Kaveri & aero-engine discussion

Postby madhu » 02 Mar 2018 07:52

JayS wrote:
Madhu, just to avoid misinterpretation, please confirm whether following points are correct or not, based on your recent interaction. Just a final check for me to store the broad points in my mind as correct. I will soon forget details.


yes you are correct.

JayS wrote:3. One key issue with LPC was blade flutter which is resolved now.


for the current engine it was solved. but he told, he is not confident of the fixes they have done. might croup again for new engine.

the big prob we have is
a) funding and political will to push jet technology. more over Jet technology is more than rocket science.
b) we do not have region specific certification standard. we have copied best from all the standards and may be over killing the program.
c) unlike ISRO , GTRE went ahead in developing its technology on its own with out giving it to private and managing most of them. this has consumed lot of man power.

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Re: Kaveri & aero-engine discussion

Postby ramana » 02 Mar 2018 10:11

Very insightful lessons learned.
Our pranams to him and his crew.

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Re: Kaveri & aero-engine discussion

Postby JayS » 02 Mar 2018 10:17

ramana wrote:
JayS wrote:
Neither, if I understand correctly.



SAFRAN is planning a new Engine with the M-88 core and the TCA periphery will be designed around it.



What does TCA stands for ramana sir..?

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Re: Kaveri & aero-engine discussion

Postby JayS » 02 Mar 2018 10:27

madhu wrote:
JayS wrote:
Madhu, just to avoid misinterpretation, please confirm whether following points are correct or not, based on your recent interaction. Just a final check for me to store the broad points in my mind as correct. I will soon forget details.


yes you are correct.

JayS wrote:3. One key issue with LPC was blade flutter which is resolved now.


for the current engine it was solved. but he told, he is not confident of the fixes they have done. might croup again for new engine.

the big prob we have is
a) funding and political will to push jet technology. more over Jet technology is more than rocket science.
b) we do not have region specific certification standard. we have copied best from all the standards and may be over killing the program.
c) unlike ISRO , GTRE went ahead in developing its technology on its own with out giving it to private and managing most of them. this has consumed lot of man power.


Thanks a lot Madhu.

If proper lessons are taken and are imbibed in the design philosophy the probability of cropping up again in next design would remain low. I am sure it must have been done.

I am sure everyone will agree to those three points you make. I have been of the opinion that nothing short of declaring it a National Mission (and treating it as such) would expedite the jet technology development.

Regarding private industry participation, we must keep in mind a fact that while ISRO received perhaps 100x more funding than GTRE and did a huge industrial work and has far better push and autonomy direct from PMO, GTRE has received pittance, produced mere handful of engines and until recently Indian industry was incapable of even producing a half decent 2 wheeler engine. There was never a chance to give out any work to private industry. No one would have been able to sustain working with GTRE unless the involvement was a pet project running on sidelines for them.

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Re: Kaveri & aero-engine discussion

Postby Will » 03 Mar 2018 20:33

It’s time India invested in full fledged testing facilities for jet engines rather than being dependent on countries like Russia for the same. Hope the JV’s include a flying testbed in India with the associated ground facilities.

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Re: Kaveri & aero-engine discussion

Postby ramana » 04 Mar 2018 01:32

TCA= Turbofan, Chamber and Afterburner.
Everything except Core.

I made that up a few pages ago so don't have type those three sub assemblies.

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Re: Kaveri & aero-engine discussion

Postby Rakesh » 06 Mar 2018 00:52

Cybaru, Ramana-ji, JayS, Indranil, Haridas-ji and others: Now check this (not the tweet, but the images especially the specifications...the last para in particular). Safran used the offset money to increase the core, which they could not do until the Rafale deal with India came along. This has multiple benefits for Safran, but similar benefits exist for India's Rafales, Tejas and possibly even the MiG-29K can be powered by this one engine. This is what Kaveri88 will be. My guess is that Safran will announce this (Kaveri88) - via President Macron's announcement - and a next venture (Kaveri200 - for the AMCA and possibly Su-30MKI as well). € 1 Billion well spent!!!! :)

https://twitter.com/Sootradhar/status/9 ... 4009163777 ---> Dassault Rafale Deal = Offset Clause starts showing results. Modi Sarkar had forced the French to the offset clause, result French agreed to invest € 1 Billion back into India. They zeroed on our Kaveri Engine project.

Image

Image

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Re: Kaveri & aero-engine discussion

Postby Indranil » 06 Mar 2018 01:04

I don't find anything new in this except a political plug of how the govts. decision is bearing fruit.

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Re: Kaveri & aero-engine discussion

Postby Rakesh » 06 Mar 2018 01:08

IR: I was very interested to know the the M88 core had growth potential till 105 kN. That is something I never knew. The Kaveri - if I am not mistaken - is supposed to be a 90 kN engine.

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Re: Kaveri & aero-engine discussion

Postby ramana » 06 Mar 2018 01:10

No. The core dia got increased to match the Kaveri requirement.

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Re: Kaveri & aero-engine discussion

Postby Cybaru » 06 Mar 2018 01:15

That's good to hear that the m-88 core has potential for LCA Mk-2 (105KN seems pretty good!). It can power the LCA mk1/1a/2/Rafale versions and perhaps even the Mig29K version if we ever manage to replace those smoky engines and make the 29K more reliable for the navy.

But if they really want to power AMCA, they may have to develop somewhere around 115-130 KN engines for it. What's the growth potential of the Kabini core? Isn't there a parallel project with RR on erj200 according to one report? That has potential to power AMCA and retrofit MKI engines. The growth potential in those engines is rather large and it has a working 3d nozzle (78KN/125KN).

This is better than the useless TOT that we have been signing. Order another 36-54 raffies with new made in India engines. Let em make the plane in France and put new engines in India.

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Re: Kaveri & aero-engine discussion

Postby Indranil » 06 Mar 2018 02:06

Rakesh wrote:IR: I was very interested to know the the M88 core had growth potential till 105 kN. That is something I never knew. The Kaveri - if I am not mistaken - is supposed to be a 90 kN engine.

I think what the aero-enigne-gurus are teaching us again and again on this thread is that number in absolution doesn't mean much.

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Re: Kaveri & aero-engine discussion

Postby Cain Marko » 06 Mar 2018 08:31

Cybaru wrote:But if they really want to power AMCA, they may have to develop somewhere around 115-130 KN engines for it. .

Why won't 105 KN work? I don't expect AMCA to weigh much more than 13-14 tons empty. Two engines pumping out 22 kgf thrust with internal fuel 6 tons and internal aam load of about 1 ton will still give extremely high twr.

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Re: Kaveri & aero-engine discussion

Postby Prasad » 06 Mar 2018 09:05

The first versions will be overweight. It'll be a miracle if they're not. Excess thrust to account for future weight is a must.

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Re: Kaveri & aero-engine discussion

Postby Gagan » 06 Mar 2018 09:44

Just take the FA-18 analogy for a second here.
The AMCA is to be powered by the same two engines in a similar configuration.

Is the FA-18 a nimble plane? Can it supercruise?
The AMCA because of the stealth shaping may be more draggy.
Then we want it to supercruise too?

What about the Navy? They'll want it to take off from its STOVL carriers with full load and more than half a tank of fuel. Can the current FA-18 do that?

The AMCA engine can't be the same thrust as the FA-18's engine !!! Atleast 10-20KN thrust more per engine is needed no?

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Re: Kaveri & aero-engine discussion

Postby Cain Marko » 06 Mar 2018 10:22

Prasad wrote:The first versions will be overweight. It'll be a miracle if they're not. Excess thrust to account for future weight is a must.


Future weight gain can be countered by future engine development. I don't see the kaveri staying stagnant. There has already been talk of 12.5kgf replacements.

Gagan wrote:Just take the FA-18 analogy for a second here.
The AMCA is to be powered by the same two engines in a similar configuration.

Is the FA-18 a nimble plane? Can it supercruise?
The AMCA because of the stealth shaping may be more draggy.
Then we want it to supercruise too?

What about the Navy? They'll want it to take off from its STOVL carriers with full load and more than half a tank of fuel. Can the current FA-18 do that?

The AMCA engine can't be the same thrust as the FA-18's engine !!! Atleast 10-20KN thrust more per engine is needed no?


Not so sure the f18 is a good analogy for a number of reasons..
1. It might be similar weight but it is powered by engines with less thrust. The kaveri will have 1 ton more thrust at least.
2. The shornet is not streamlined for transonic acceleration.. Look at the gripen. With rather inadequate thrust still managed marginal super cruise.
3. The AMCA will have internal carriage of weapons in stealth profile reducing drag and providing plenty of excess thrust because internal stores won't allow for super heavy payloads near mtow
4. For naval ops, it will be better than Rafale in twr, totally doable on stobar setup for stealth config. For bomb truck loads, cats are a must anyway.

I'm guessing that the AMCA kitted out for stealth and Max internal fuel will have a twr well in excess of 1.0. probably similar to a typhoon with 6 aams. Totally capable of supercruise.

Overall, a some compromise, but rather effective.

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Re: Kaveri & aero-engine discussion

Postby JayS » 06 Mar 2018 11:55

Can anyone find some good source tracing history of development of M88..? Or if its done on BRF previously, dig out old posts..?

The M88 flows like this it seems, starting from ~1996 when first version entered service: M88 > M88-2 > M88-3 > M88-4E

There have been at least two upgrade programs. THEO during early 2000's demonstrated 90-95kN engine (I think M88-3 which never went ahead of TD phase, it had higher mass flow rate, new AB and all). TCO is the improved Ownership cost improvement package which forms current M88-4E. I think M88-4E = M88-2 + TCO.

"Core has potential of 105kN" is pretty vague statement. Going from 75kN to 105kN is not organically possible. From 75 to 95kN itself took quite a lot of design changes. But if they put together THEO, TCO and some more stuff, 105kN is possible. But I suspect it will take hit on life of engine and the life numbers would be similar to M88-2 and not M88-4E.

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Re: Kaveri & aero-engine discussion

Postby Singha » 06 Mar 2018 12:19

keypubs, another post said it was ground tested in 2005. if funds be given a M88-3-EPE would be developed and rolled out.

=======

M88-3 with the same performance of the -2 but with a lower cunsumption, better reliability, less maintenance
M883- with the same MTBF than the -2 but with more thrust.

Since nobody show interest into the more powerful -3, the M88 ECO is develloped for the french army and could be buy for the Rafale F4

Find on http://www.deagel.com/Powerplant.htm
M88-2
Diameter/Caliber 700mm 27.56-in
Length 3.5 m 12-ft
Max Weight 897 kg 1,978-lb
Thrust 75.5 kN 17,000-lb
Airflow 65Kg/s

M88-3
Diameter/Caliber 790mm 31.1-in
Length 3.6 m 12-ft
Max Weight 985 kg 2,172-lb
Thrust 89.9 kN 20,250-lb
Airflow 72Kg/s

It is said that the -3 need different air intakes on the rafale which are already fully develloped and "decrease the RCS".

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Re: Kaveri & aero-engine discussion

Postby JayS » 06 Mar 2018 12:41

^ I saw those figures. I PS-ed in my post above but when I submitted changes, your post appeared. So I deleted them again. There is quite a bit of interesting info on old forums but almost all the links are dead.

I found another program - PHT - under which Schema demonstrated upto 2100K TET. This was followed by THEO and later by TCO.

A news cut-out from 1998 or so: https://goo.gl/images/86fy2s

I have some more info, but I will post when I see some proper source to verify. But others willing to spend time can use key words I gave above.

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Re: Kaveri & aero-engine discussion

Postby Singha » 06 Mar 2018 13:18

it seems the rafale program suffered a big decline in funding from around 2005 for lack of cash rich export customers and only got next injection of funds some 10 years later from egypt et al. the french govt must have been giving bailouts in the meantime.

in the same time frame the F-18 added a lot of new capability, and is adding more. rafale forget new stuff had to delete the IRST to save cost.

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Re: Kaveri & aero-engine discussion

Postby JayS » 06 Mar 2018 14:51

OK Found one more reference, flight global article from 1999:
https://www.flightglobal.com/news/artic ... m88-51979/

The M88-2 has a thrust-to-weight ratio of 8.5, producing 11,250/16,850lb of dry/afterburner thrust (50/75kN). The engine has proved extremely reliable in flight tests to-date, by early May building up 6,200 flight hours on the Rafale, giving a total of 16,400h, including test bench running. "It is now ready for entry into operational service," says Jean Massot, M88 general manager


Just look at the number of hours of testing before EIS. This was Snecma's n-th engine, remember.

Snecma is developing the M88-2 Stage 4, which has the same thrust as the standard M88-2, but incorporates improvements aimed at extending the service life of the engine and reducing fuel consumption, which Massot says "will also reduce operating costs significantly". Another benefit will be to improve the duration of the low-level penetration missions.

The changes include the introduction of three-dimensional high-pressure (HP) compressor and turbine blades, blisks (one-piece blades and discs) improved thermal coatings on the HP turbine, and advanced cooling channels for the combustion chamber. The Stage 4 development will be ready in early 2001 and the modifications will be retrofitted to the M88-2. It will power the 48 Rafales ordered in the Government's multi-year procurement plan.


This, I think, eventually became M88-4E and was only recently materialized as opposed to the planned 2001 date.

A further development, the M88-3, rated at 9.5t thrust, still awaits funding, but has been benchtested on a privately funded demonstrator. "We are proposing the M88-3 to the French government for the future standard of the Rafale in the early 2000s and to prospective export customers", says Massot.

The M88-3 features a new LP compressor with higher mass flow (from 65kg/s in the -2 to 73.4kg/s). A new variable stator vane stage has been introduced, permitting the engine to operate at optimum conditions through a much wider range, reducing part-power-specific fuel consumption and providing more operational flexibility to suit the Rafale's multimission role. The development comes out of Snecma's CENTOR LP compressor research programme and from other exploratory developments carried out by Snecma in recent years.


This part constituted THEO program I suppose. They demonstrated 90-95kN thrust based on higher inlet mass flow rate and improved TET.

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Re: Kaveri & aero-engine discussion

Postby JayS » 06 Mar 2018 14:54

This one particular post from some forum I never heard of. Most or all the links are dead. But whatever I have cross checked was correct. This gives quite a good overview of M88 dev history. Note it mentions a news from 1995 which talks about plan for M88-4 with 110kN version which would also be used for M2K re-engine, which we know never came into being.

http://www.network54.com/Search/view/21 ... page=46726

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Re: Kaveri & aero-engine discussion

Postby Neela » 07 Mar 2018 11:43

JayS Sir,
I wonder what work is there when you want to fit M88 core into the Kaveri. What is the learning there for us ?
It does seem like there is very little R&D benefits for us and a big upside to Safran on the sales front.

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Re: Kaveri & aero-engine discussion

Postby JayS » 07 Mar 2018 11:56

Neela wrote:JayS Sir,
I wonder what work is there when you want to fit M88 core into the Kaveri. What is the learning there for us ?
It does seem like there is very little R&D benefits for us and a big upside to Safran on the sales front.


As per Madhu's feedback, the is plan to keep the kabini core and debug the LP system.

I have already said n number of times, you don't fit a core from one engine to LP system of another. You don't upsize or downsize a core. You always upsize or downsize LP system. What you do is you redesign (upsized or downsized existing LP system mostly) LP system for a core of your choice. An engine with M88 core will remain to be M88 engine. In no scenario it becomes Kaveri. And even if we design our own LP system for M88 core to get a new version of M88, it would take more than 2yrs for sure and we would really gain only marginally over and above what we already have achieved from Kaveri.

There are really two alternatives:
1. Simply debug the current Kaveri LP system for achieving target thrust. This is possible in 2yrs and this is what French will do, as per my opinion. Some tech infusion like replacing DS bladed by SCB will give enough jump to 90kN for now. The 110kN version would need significant tech infusion, upsizing and redesigning all the modules.

2. Snecma basically sells us their already developed M88-3 engine as it is.

Only these two options are feasible in 2yrs timeline. I'll eat my hat if Snecma manages to fit existing M88 core (-2 or -4E any of the two versions) into Kaveri's existing LP system and make it flightworthy in 2yrs as the claims have been.

The aspect of strategic independence is a different matter, not necessarily related to technology. It may make sense to simply buy M88-3 engine from France if they offer us good terms and provide enough strategic independence. That would be only for LCA. The existing technology would be sufficient for MK1/MK1A and with little stretch Snecma might be able to reach 98kN level or even surpass it slightly. And we keep developing 110kN K10 version side by side and we should be able to still catch up for AMCA.

PS: There is only one scenario where M88 core is a good fit for Kaveri's LP system and that match is doable in 2yrs (however we must remember, its the LP system of Kaveri which has all the issues so this doesn't make problems go away, they have to be dealt with still, to make the engine reliable). And that is, the Kabine core already resembles very well with the M88 core, due to French consultancy over the years. But I don't want to consider it plausible unless I see some really compelling evidence. But even in that case I do not see upscaling of M88 core happening. Its either M88-2/4E core as it is or its M88-3's core as it is (by M88-3 I refer to the demonstrated core from PHT and THEO programs as mentioned in posts above).

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Re: Kaveri & aero-engine discussion

Postby Haridas » 07 Mar 2018 13:46

Indranil wrote:
Rakesh wrote:IR: I was very interested to know the the M88 core had growth potential till 105 kN. That is something I never knew. The Kaveri - if I am not mistaken - is supposed to be a 90 kN engine.

I think what the aero-enigne-gurus are teaching us again and again on this thread is that number in absolution doesn't mean much.

For example the engine core be configured with a higher bypass and a thick nacell will give even more thrust but thrust will drop off significantly as speed increases and bypass can't be sustained beyond certain speed. Final engine config must support a/c operational parameters' optimization space corners.

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Re: Kaveri & aero-engine discussion

Postby madhu » 07 Mar 2018 19:15

Here is the calculation of Kaveri engine that i did based on stagnation point. maitya's sheet is based on static thermodynamic points which is not accurate. feel free to comment.
if we populate actual values we can improve it further. currently i am calculating only dry thrust. when i get time i will update it with thrust with AB.
Image

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Re: Kaveri & aero-engine discussion

Postby JayS » 07 Mar 2018 21:54

Excellent work there, Madhu.

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Re: Kaveri & aero-engine discussion

Postby Zynda » 07 Mar 2018 22:26

Good work Sir.

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Re: Kaveri & aero-engine discussion

Postby ramana » 08 Mar 2018 00:07

JayS or Maitya, Can you go through madhu's spreadsheet and tell us what's the theoretical performance of the Kaveri as we stand now?

To me the first is the sfc is 1.92 vs 1.19 for dry thrust of 48KN.
Not good news.

madhu, Please run it by the good doctor and see if he agrees.


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