Kaveri & Aero-Engine: News & Discussion

[Rakesh]

Avtar, I agree with Ramana-ji. BRF's engine gurus are on to something. Let them work it out.

Let GTRE fix the tactical problem, so you and me can celebrate the strategic solution

[Katare]

After a lot of matha-pachchi and head banging on jet engine technology over many years, which is mostly beyond comprehension of my brain anyhow, I have learned one thing that it's all about TET. If we can add another ~75C to Kaveri TET, we would get the thrust we need. Rest of the parameters can be tweaked and optimized iteratively but TET needs you to have Uber massa grade technology upfront - Single crystal blades/blisks, parts with intricate cooling vanes, thermal barrier coatings and exotic high temperature materials.

[Katare]

Here is a graph showing linear relationship between inlet temperature and core power -

TET and core power

[Haridas]

GTRE should have had N^3 and Vina as program consultants.
And they would have achieved it by now.

I heard that Mangolia does not allow their Yaak herders alternative profession

[Avarachan]

Over the years, I have learned not to under-estimate India's national-security establishment. I wonder what is going on behind the scenes.

What is curious about the Kaveri project is that certain projects have received the necessary funding for the enabling infrastructure to be built (IGMDP, Arihant program). But the Kaveri project has not. All this talk of success and failure has to be seen in that context. I don't think any of us know what's really going on.

[kittigadu]

The BPR sets the propulsion efficiency and the OPR the thermodynamic efficiency of the engine. Based on the characteristics posted, Kaveri does not compare well with M88 in both aspects. It’s SFC is likely to be worse.
The BPR is likely lower because the core is likely producing less specific thrust because of the low TUrbine inlet temperature, and is hence oversized. The turbine inlet temperature sets the specific thrust. I am assuming the 1850 k posted for turbine inlet temperature is at the inlet to the high pressure turbine nozzle. 1850 k translates to about 2870 F. Even this number is low compared to even modern commercial jet engines. At Steady state high power, for new engines, this number is around 3000 F, and goes up as the engine deteriorates. For military engines, the number will be higher.

There is no getting around this. Help is more readily available for the cold section/compressor, whether from Snecma or Rolls or GE or Pratt, hence the OPR can be fixed with help. However to increase the Turbine inlet temperature, single crystal nickel based alloys need to be developed. Nobody is going to give this technology. It has to be developed from scratch . Better cooling designs for combustor, nozzles, blades, and shrouds has to be developed. Nobody is going to give these either.

It is going to be a long haul.

[jaysimha]

https://www.drdo.gov.in/drdo/drdojsp/downloadtndr.jsp?tenderName=18043&McrId=GTRE*Gas%20Turbine%20Research%20Establishment&p=RFI.pdf

GTRE was to Set up Twin Test Cell for developmental aero gas turbine engines upto 130kN thrust class

Dont know what is the status now??

[JayS]

JayS, Maitya said it better than I can

So even though BPR in itself doesn’t really change the Thrust rating etc, it’s an indicator of the maturity of the injin technology and of a better efficient turbofan injin.

It does and it does not. This is gross simplification. If your system requirement for propulsion unit dictates low BPR, you go for it, irrespective of what others might think of your technical capability. There is no universal truth saying high BPR = high efficiency across the whole spectrum of possible fighter jet propulsion. Its only valid in a certain conditions. Nor high efficiency is always a primary concern. In that sense, having low BPR or high BPR does not *always* indicate level of technical capability. The currently being worked on SST in US will need a low BPR turbofan for it, quite low compared to BPR of 15 that the next PW1000G engine will have. If GE makes an engine for SST with lower BPR, does that make GE in inferior OEM suddenly..??

Kaveri's BPR is out of flat rating requirement, not a forced result out of any technical capability gap. Similarly F119 has lower BPR than its other contemporaries, still it used to be epitome of technical capabilities in its hay days. Olympus engines from Concorde are perhaps the most efficient jet engines ever despite having BPR of 0. They can rival even the modern engines in terms of efficiency. BPR is not an issue with Kaveri. It would have achieved all its design goals had the other issues taken care of, especially with the A/B.

You can increase Kaveri's BPR, but then you will have to forgo flat rating, unless you increase its TET capability to today's state-of-the-art (well beyond the practical limits possible in 80s when Kaveri was conceived) and run it at reduced TET to maintain flat rating.

[Neela]

Are we going in circles here ?
There is a new discussion.
Maitya brings in the excel sheet and explains the problem using numbers. This time ion BPR. 3 pages later it boils down to

- TET
- OPR

And Im reminded of that 1 Pinglish post from N^3.

[JayS]

Are we going in circles here ?
There is a new discussion.
Maitya brings in the excel sheet and explains the problem using numbers. This time ion BPR. 3 pages later it boils down to

- TET
- OPR

And Im reminded of that 1 Pinglish post from N^3.

When we are trying to invent non-existent problems, we are bound to go in circles, especially with no real information to cross check any of the hypotheses. That's why I do not want to speculate anymore. Everything that could be said, is already said multiple times.

Even with this M88 core for kaveri, is nothing new. If you open discussion from 2009 and 2012, I am pretty sure you will see exact same things discussed there.

[JayS]

Over the years, I have learned not to under-estimate India's national-security establishment. I wonder what is going on behind the scenes.

What is curious about the Kaveri project is that certain projects have received the necessary funding for the enabling infrastructure to be built (IGMDP, Arihant program). But the Kaveri project has not. All this talk of success and failure has to be seen in that context. I don't think any of us know what's really going on.

Exactly. But one thing is for sure, funding is not flowing, even under new government. Why is the question.

[Prem]

GTRE should have had N^3 and Vina as program consultants.
And they would have achieved it by now.

I heard that Mangolia does not allow their Yaak herders alternative profession

Use Nagpash.

[JayS]

Avtar, I say there are two ways of looking at problems: strategic and tactical.
Strategic is also called global and looks at many factors that could be used to tackle the problem.
Tactical or military looks at the immediate root cause and tries to fix that.

And the big lapse is to mistake one for the other and use the wrong solution.

Kaveri despite all the global/strategic factors is really a tactical problem.

It does not develop the required dry thrust.
You fix that and you have a winner.
We have narrowed it down to the core.
Now what exactly in the core is being explored.

Actually Kaveri does produce dry thrust with only 2-3% of short-fall from design goal (52kN vs 54kN or 49kN vs 52kN something like that). Where it falls short it wet thrust.

That is if we believe accounts from various official and reported accounts. Unless you know something from chaiwalla that I am not aware of.

[SaiK]

Losing bluetooth signal here.. and thread on bpr

In any case, the foreign partner was more interested in a much larger project that would have seen the creation of a new core for the Kaveri design for 90 KN plus wet thrust. That project however is also not seeing light of day because GTRE is probably seen as a failure lab. https://twitter.com/SJha1618/status/965872249520775173

[Yagnasri]

Mango Question: Have we tested it for a long duration under dry thrust. If it is ok for dry thrust then we can use it for our UCAV?

Thanks in advance.

End Mango post.

[JayS]

Mango Question: Have we tested it for a long duration under dry thrust. If it is ok for dry thrust then we can use it for our UCAV?

Thanks in advance.

End Mango post.

Only available info is that more than 3000hrs of ground testing is done. Its anyone's guess how much of it is at full thrust. But its likely that they have run 150-hr endurance test. And since it appears than dry thrust is quite alright, Ghatak has got a go-ahead with AB-less Kaveri as power-plant.

[Yagnasri]

thank you guruji.

[JayS]

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).

One observation, the sfc value in the above excel for Kaveri-prime is bit on higher side than the claimed figure of 0.78kg/kN-h.

[ramana]

We can start with the dry thrust, SFC, TWR, max obtainable pressure ratio of Kaveri with the original M88 core. Is it ideal? If not, how has the core to resized (obviously up), but by how much?

JayS, See above post from Indranil.

Looks like we have a difference about the dry thrust.

My beef about GTRE is their total opaqueness and report only to dead hand or live fist in hushed whispers of good news around the corner for the last three decades.
Tejas succeeded due to the ADA transparency so everyone knew where they were and got support.
When even Saurav Jha writes about lack of trust in GTRE its something for he is an open Indian defence products endorser.

Trust is built on three Cs: Communication, Character, and Capability

Communication is further components:
- Trust in "Listening to Learn"
- Trust in understanding (purposes, concerns, and circumstances)
- Trust in judgment
- Are commitments accurate? (Clear, specific promises and requests)
- Are commitments authentic? (based on shared purpose)


Character components:
- Follow through in commitments?
- Honest about results?
- Reward integrity?
- Address poor performance quickly, accurately, and authentically?

Capability components:
- Are skills and experience trusted?
- Trust to involve others appropriately when personal capability is insufficient?
- Do you communicate breakdowns in your ability to perform ASAP?

Each of these 12 can be put in a table and assessed as STRONG, WEAK, ON TRACK

I had given this to Saik long back for his use.

Now where would GTRE score?

[Avtar Singh]

No problem, I am not criticizing anyone. I am sure it will all work out.
Since waiting for LCA to fly over the 90s, I watch this page most closely....
Waiting for that jet engine.

As we all know this tech surpasses all others only a few can do it.
West has been practising since WW2!!

[JayS]

You dont chnage core to match LP system. Its the other way round. M88 core will not take up anything more than what its designed for today, without quite a bit of rework, may be a decade long work. If it has to be fitted into Kaveri, then Kaveri's existing LP system has to be modified to match it. Still it cant be done in 2yrs unless the LP was always quite match-able to M88 core.

[Avarachan]

My beef about GTRE is their total opaqueness and report only to dead hand or live fist in hushed whispers of good news around the corner for the last three decades.

All strategic programs in India are protected with multiple layers of disinformation. The reason certain information was released about the Agni tests, for instance, is that it was not possible to conceal that information. However, if it is possible to conceal and dissemble as to where a program will be at a certain point in time, that should be done. Those who need to be informed as to the truth, will be. Those who do not (which I imagine includes all of us on BRF) will not.

For all we know, the primary purpose of the Kaveri program could have been to create a reliable (if heavy) core which could be used in stealthy subsonic aircraft (like the Ghatak or the F-117). If that was the real goal, perhaps the Kaveri project will be remembered as a great success. I'm aware of the stated goals of the Kaveri project. Nonetheless, I've learned over the years that when it comes to strategic programs, the stated goals are often not the actual goals. For one thing, the funding of the Kaveri program does not align with any credible analysis of the stated goals. That makes me wonder if something else is going on.

As JayS said above, as of now, we BRF members simply do not have enough information to know in detail what's actually happening.

[JayS]

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).

Interestingly current Kaveri shows better propulsive efficiency compared to the Kaveri-with-M88-core which has higher BPR...!!

Also interesting to see the jump in thermal efficiency from current Kaveri to improved kaveri. From 0.43 to 0.6. Much higher than one would expect from the relatively small increase in Pr and TIT that we have here.

[Aditya_V]

So is this a possibilty for AMCA, what would be the weight of the improved Kaveri K9, can 2 improved Kaveri with combined dry thrust of 146Kn, power an empty weight AMCA weighing about 8 tonnes with 3.5 tonnes of fuel and 1.6 tonnes for 4 aam's and 2 bombs in internal bay still supercruise?

[JayS]

So is this a possibilty for AMCA, what would be the weight of the improved Kaveri K9, can 2 improved Kaveri with combined dry thrust of 146Kn, power an empty weight AMCA weighing about 8 tonnes with 3.5 tonnes of fuel and 1.6 tonnes for 4 aam's and 2 bombs in internal bay still supercruise?

There are three possible answers - No, Yes, Maybe. Pick your choice. Your guess is as good as anyone else's at this stage.

[NRao]

So is this a possibilty for AMCA, what would be the weight of the improved Kaveri K9, can 2 improved Kaveri with combined dry thrust of 146Kn, power an empty weight AMCA weighing about 8 tonnes with 3.5 tonnes of fuel and 1.6 tonnes for 4 aam's and 2 bombs in internal bay still supercruise?

By when?

2030? More than likely, yes. Although 146 kN seems high. 130-135 kN .............more than likely.



No matter what, which ever version of the Kaveri, she has a very long way to go. Tests, certifications, productization, then scaling up, while maintaining quality and cost. Engines are engines, they are finicky, temperamental, unpredictable, ............... I would rather wait till one actually comes out as a product as opposed to a lab article.

[Rishi_Tri]

Over the years, I have learned not to under-estimate India's national-security establishment. I wonder what is going on behind the scenes.

What is curious about the Kaveri project is that certain projects have received the necessary funding for the enabling infrastructure to be built (IGMDP, Arihant program). But the Kaveri project has not. All this talk of success and failure has to be seen in that context. I don't think any of us know what's really going on.

Yes, people who understand importance of Missiles, Nuclear Submarines, would understand importance of desi engines too. In another three four years from now, Kaveri would have been under development for almost three decades. Given all the news around failure, failure lab etc., external help, I am inclined to speculate that the engine is closure to its redone goals. If you want to hide something, call it a failure.

[maitya]

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).

One observation, the sfc value in the above excel for Kaveri-prime is bit on higher side than the claimed figure of 0.78kg/kN-h.

JayS and others ... pls note do NOT use the absolute numbers mentioned in the above model to compare with published parameters/ratings of a working/in-dev injin etc.

This model is a simplistic (overly simplistic, as I've mentioned above and multiple times in past 3-4 years) presentation of various technical aspects of a turbofan ... some very very atrocious assumptions (e.g. no mention or usage of isentropic efficiency anywhere etc) have been made to keep it as simple as possible and aid in a discussion forum like this.

What this model can be used to, is to put in various parameters and then compare the output parameters within this model - not with outside figures/results.

As an example, the SFC value of 0.92 can be compared with 1.92 and 0.82 ... but not with 0.78kg/kN-h etc as has been published by various other more authentic sources.

[JayS]

One observation, the sfc value in the above excel for Kaveri-prime is bit on higher side than the claimed figure of 0.78kg/kN-h.

JayS and others ... pls note do NOT use the absolute numbers mentioned in the above model to compare with published parameters/ratings of a working/in-dev injin etc.

This model is a simplistic (overly simplistic, as I've mentioned above and multiple times in past 3-4 years) presentation of various technical aspects of a turbofan ... some very very atrocious assumptions (e.g. no mention or usage of isentropic efficiency anywhere etc) have been made to keep it as simple as possible and aid in a discussion forum like this.

What this model can be used to, is to put in various parameters and then compare the output parameters within this model - not with outside figures/results.

As an example, the SFC value of 0.92 can be compared with 1.92 and 0.82 ... but not with 0.78kg/kN-h etc as has been published by various other more authentic sources.

Within the model's limits, what does SFC number comparison signifies..? We have Kaveri at 1.19 and M88 at 0.82 in their existing configs as per the model. That seems like a lot of difference. But in reality both the engines have exactly the same dry SFC of 0.78lb/lb-hr as per respective official numbers.

On an unrelated note, the comparison of Kaveri and M88's official numbers is interesting. While both have about the same dry thrust, the wet thrust for M88 is 71kN vs targeted 84kN of Kaveri. (As per some accounts Kaveri was able to demonstrate 72kN wet thrust in flight). That explains significantly higher wet SFC for Kaveri as compared to that of M88.

[Cain Marko]

So with all this charcha about kaveri, m88 and what not, can we expect some lungi dance news about Rafale and kaveri when macaroni is served in March?

Last I remember, the French were damn confident of fixing the kaveri with m88 core in very short order...2017-18. I had also surmised that this was a must for the French to get more Rafale orders. Are we on track for French Champagne?

[Rakesh]

Posted by BRF Member nvishal

-----------------------------------

The Indian fighting aircraft Tejas soon powered by the M88 engine Rafale?

According to our information, the negotiations between Safran and DRDO are on track to power the LCA with the M88 as part of the Kaveri program.

The new France-Indian partnership could be the subject of an announcement during Emmanuel Macron's trip to India on March 10th

https://www.latribune.fr/entreprises-fi ... 69696.html

Article is in French. Used google translate

May be true. May also be plain gossip

[Rakesh]

Posted by BRF member pralay

-----------------------------------------------

https://www.latribune.fr/entreprises-finance/industrie/aeronautique-defense/l-avion-de-combat-indien-tejas-bientot-propulse-par-le-moteur-m88-du-rafale-769696.html

Article is in French. Used google translate

May be true. May also be plain gossip

That meant m88-Kaveri not plain vanila m88

[Rakesh]

The most interesting piece from the above article is this sentence ---> "They could soon succeed and this new Franco-Indian partnership could be the subject of an announcement during Emmanuel Macron's trip to India on March 10th."

Is it going to be a vanilla announcement or something bigger, we can only know on March 10th.

[Will]

If the French are investing 1 Bn of their own money think there is something bigger in the pipeline. Probably a joint development of an engine for the AMCA.

[Rakesh]

Posted by BRF Member Will
—————————

Wonder how true this is. There is certainly something going on with safran and rolls Royce on the engine front.

http://idrw.org/french-media-m88-kaveri ... ore-163465

[Rakesh]

Are we on track for French Champagne?

I would hold off on uncorking the champagne. Let’s see what President Macron has to say on March 10th.

[Vips]

France knows it has to offer something huge or desperately required by India for it to have any chance of securing more business.

[ramana]

If the French are investing 1 Bn of their own money think there is something bigger in the pipeline. Probably a joint development of an engine for the AMCA.

Its the offset money.

They are supposed to channel it back.


If it happens will be happy.


The M88Core-Kaveri has turbo fan+ engine casing and afterburner section and M88 core.
We know the M88 core is smaller than the Kaveri casing from earlier reports.

I think there are two options here.

1) Increase the M88 core diameter to match the Kaveri system. This means keep the rest of the (TCA) T/F+ Casing+ AB same.
- This option is risky as changing core to match the TCA could be tricky.
- However GTRE will learn the most from this option as they learn to resize the core.

2) Keep the M 88 core as it works and redo the TCA as GTRE knows how.
- Could be long drawn out process as three systems have to be developed: T/F+ Casing + AB And more costly from Indian side. Kind of defeats the offsets as India gets to spend twice.
- GTRE wont learn anything new as they already had developed the TCA. Redoing the TCA is not new technology.


I would choose option 1 as from India learning point of view this is better option.

And this way India has its own Kabini + core that can be leveraged into other engines;
Mig 29 and Su 30 engine replacement programs eventually.

[chola]

I think we will learn something by looking at the M88 core and how it is incorporated into the Kaveri’s intake, exhaust, case, etc. Obviously, the key to all this is the material going into the French engine and that os something they will keep secret but hopefully we can gain some insight.

[ramana]

M88 is an old 1980s core so its technology won't be exotic.

But resizing the M-88 to fit the Kaveri TCA will improve the GTRE expertise.

The sad thing is that GTRE never even got more than $300M for total Kaveri development and here Safran will be bring in 1.2 B Euros of our own money.

Thanks to the morons in MFA and MOD who won't bat for requisite funds.

And no champions for it in the IAF.

This is deadly combination that will ensure India gets defeated.