Kaveri & Aero-Engine: News & Discussion

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hariks
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Re: Kaveri & aero-engine discussion

Postby hariks » 02 Feb 2009 13:14

Thanks Rahul for presenting the big picture. Kind of makes things clear why we won't get help with the blades.
I understand that Kaveri has achieved quite a bit considering we had no prior engine development experience and the major engines in the market today are below Kaveri's required thrust specifications (including flat rating). We set out to beat the world in the first attempt. It would be great if we really get there, even if it takes a little bit more time.

On the second question, my guess is that the current alloy used may not stand at all when the inlet temp is raised to 1800 deg, practically ruining the core, which is probably why higher thrust is not demonstrated yet. 1400 to 1800 is a 400 deg C range, so will we see increased thrust at say 1600 deg C? Perhaps only GTRE labs personnel will know these details.

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Re: Kaveri & aero-engine discussion

Postby adarshp » 02 Feb 2009 14:01

hariks wrote:On the second question, my guess is that the current alloy used may not stand at all when the inlet temp is raised to 1800 deg, practically ruining the core, which is probably why higher thrust is not demonstrated yet. 1400 to 1800 is a 400 deg C range, so will we see increased thrust at say 1600 deg C? Perhaps only GTRE labs personnel will know these details.


Hari, while you are right that we will probably see incremental rises in the entry temprature as part of opening up the engine to desired thrust levels, deducing that the alloy does not meet the temprature melting point requirements is not so straight forward from what I have read. It appears that alloys themselves can be broken into two categories into this one -

- Regular alloys which display behavior similar to Iron etc, where you see the metal becoming red hot and malleable much before you get to melting point. Case in point is how steel based railway tracks need gaps to cater for high summer tempratures causing major stress and expansion under pressure of trains running over them.
- Super alloys which if they dont have structural weakness along stress points can take high load and stress and still not bend out of shape till about 90% melting point. SC blades came into existence to ensure that there are no weak points (microscopic in nature) along stress areas in turbine blades.

What I am asking is probably coming down to this -

I hear two things about the Kaveri, one we have metalurgical issues with Kaveri and two we need SC blades to make the thing meet specs. If it is the metal we are probably further back in the process, and though not easy, we can demonstrate that we have a suitable alloy even before we get SC blade technology. SC balde technology is all about metal casting, however, alloy behavior can just as well be demonstrated on a metal block. You have to validate melting point and smooth edge behavior and resilience as you approach melting point. Are we done with this?

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Re: Kaveri & aero-engine discussion

Postby Rahul M » 02 Feb 2009 14:08

somnath wrote:These need to be taken with a pinch of salt IMHO. There is no "verifiable" way any country can say "stop project X if you buy Y from me".

on the contrary there are hazaar ways to verify. :D
simiilar instances are also not unknown.

avro arrow or the lavi ?
somnath wrote:What stops India from secretly continuing with LCA AND running the assembly line for Mig33? The typical method is actually more subtle - once the domestic project acheives a measure of "success", approach the end client with a "cheaper" alternative.

not really, for an open country like ours carrying out a big project like LCA fully indigenously was near impossible. even if you discount the huge footprint of supporting orgs, we still needed lots of international support in many areas.

the typical method you elaborate is one of the *many* ways that are used to prevent self-sufficiency, not the only one.

others being denying critical items after promising to do so, poaching vital personnel at cruical times and so on.

missed answering this :
babbupandey wrote:Rahul, what is the source of this information, please? If it is true then it is troublesome, to say the least, the clout amrikis and russkies have in India.

clout ? I would think they had pretty low clout ! neither the F-20 nor the Mig-33 was accepted and the LCA program is still alive and kicking !!

====================
Of course, if foreign co's sense that IAF is absolutely serious about LCA or if helping out on SC blades is linked to even more juicier deals, then some amount of assistance is possible.
bottomline is, while everything is possible, you have to assume and be prepared for the worst.

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Re: Kaveri & aero-engine discussion

Postby hariks » 02 Feb 2009 14:28

Thanks for the clarification I hope that the alloy is already solved now - since it hasn't come up in discussions/material on Kaveri as a problem area. I thought the alloy has to be cast by growing single crystal for it to withstand the stress up to 90% of melting point. I must say my knowledge in this area is limited to Wiki searches.

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Re: Kaveri & aero-engine discussion

Postby Neela » 06 Feb 2009 19:05

Some information in the Jan 09 DRDO newsletter.

http://www.drdo.com/pub/nl/2009/jan09.pdf

Posting some relevant bits:
On the Kaveri; Engine front, discussions are on with
the Indian Air Force, HAL and Snecma in evolving
appropriate action for joint development to higher level of
thrust and capability. Meanwhile Ktweri Marine Gas
Turbine successfully got tested for 12 MW power output at
the Naval Facility at Visakhapamam.



Just realised this....how come GTRE is not mentioned?
Is there a disconnect between GTRE , HAL and the IAF?



A number of accomplishments have been made in the
Materials group of laboratories; these relate to camouflage
pattern generation software, lightweight synthetic life
jacket, water purification system, composite armour for use
on the lightweight Helicopter, based on advanced ceramic
and polymer composites, hollow ceramic cores for cooling
channel in Gas Turbine blades and engine components
and
high temperature gasket for sealing system ofejector system
for LCA are otherinterestingdevelopments

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Re: Kaveri & aero-engine discussion

Postby K Mehta » 11 Feb 2009 19:50

X-posting from AI-09 thread
k prasad wrote:Ok.... this is the GTRE story - (someone come up with sad music plz).... from the Aeroseminar.

An overview of the Kaveri situation was provided by the GTRE director, T. Mohan Rao, who was accompanied by his senior scientists. The hall was packed, and the language and tone of his speech was sadly self-depracating and pleading. Almost as if DRDO has also started losing faith - he had to explain whats going on and why its happening. Sad to see, but there are clear silver linings in the story.

1. He pointed out that the change in IAF requirements and the increase in all up wt by 2 tons killed the Kaveri as they knew it, simply because it could not in any way be able to achieve the new requirements... he was quite angry that they had been blamed for what was obviously not their fault, ie, a low-performing Kaveri for the updated reqs. Bypass Ratio is 0.16 to 0.18... he pointed out that if it had to meet the new stds, the bypass would have to be at least 0.35 to 0.45.

2. 4 Cores and 8 Kaveris built, 1800 hrs testing done.

Thrsut demonstrated: 4774 kgf dry (design value reached). 7000 kgf reheat (2.5-3% shortfall)

3. Pressure ratio - 21.5 overall.

Fan - 3 stage, 3.4 pressure ratio, Surge margin>20.
Compressor 6.4 pressure,Surge>23.
Combustor - efficiency >99%, high intensity annular combustor. Pattern factor of 0.35 and 0.14

Note: These are ACHIEVED values.

4. The present Kaveri will not power combat LCAs, although it will be fitted to an LCA within 9 months. The new program, which is the Kaveri with Snecma Eco core of 90kN will be used. The preslim design studies and configuration have beeen completed.

5.Birdhit requirements of 85% thrust after hit at 0.4-0.5 Mach have been shown and achieved.

6. He pointed out the major factor in delays being them not being given enough infrastructure and testing facilities - Govt has not given funds, babus have sat on them. Instead, they have had to go to CIAM in Russia and Anecom in Germany for tests.

He mentioned that this was the biggest problem - one of the issues they have was in engine strain and the blade throws - they tried to isolate all the causes for 3 yrs, but only when they took it to CIAM for the Non Intrusive Strain Measurement (NSMS) tests did they realize that there were excess vibrations of the 3rd order of engine frequency being developed.... imagine if the facility was there in india.

Then, the compressor tests also, it was only at the Anecom that they could see that the 1st 2 stages were surged by 20%, while the rest were "as dead as government servants" (his quote - shows how low on confidence they are i guess). He pointed out that that would have saved a lot of time and money if that facility was in india. They have since fixed the issue.

Then, the afterburner tests, (the much highlighted high altitude failure) at CIAM - the reqt is for 50% thrust boost over dry thrust at 88% efficiency. The K5 prototype failed in 2003, after working perfectly in the GTRE. They realized that they could not achieve lightup at high altitudes (Dry thrust worked ok).

They took anothe new engine block and the afterburner worked perfectly and has been certified to 15 km.

7. The good news..... they will conduct complete engine trials in CIAM in March. If these trials are successful (and they are highly confident), the Kaveri will be integrated on the LCA within 9 months.

The KADECU FADEC system with manual backup has also been fully certified.

8. The bad news again - The present requirements would need the core to pump out 15-20% more power, which is impossible... hence the eco. Not that there is anything wrong with the core.

He mentioned that otherwise, the Kaveri has met the original requirements, or will meet within the next month, and is good for all other uses except a "combat LCA" - ie, CAT, LIFT, LCA Trainer, etc.

9. When asked where we lack, he mentioned 4 key areas

a. BLISK - integrated single Blade and Disk
b. Single Crystal blades - he categorically said - We do not have that tech at all.
c. Thermal Barrier Coatings - TBC - very critical for high temp engine operation. A talk on this by an American Indian prof attracted a house full audience. He mentioned that this is highly critical and export controlled, so they dont have it.

The last two points were mentioned by Dir, DMRL as one of their areas of research, but I was not able to quiz him on it. PLEASE QUIZ ANY DMRL GUYS U MEET ON THIS.

Mohan Rao appealed that people should realize that this tech takes time, and money, and more importantly, willpower and support.... its not being given by foriegn nations, so if we have to develop, it needs support. This stance found strong support from Saraswat, Sundaram and Selvamurthy in the closing ceremony.

They are not looking at TVC just yet, and it is in the hands of other labs at the moment.

However, the ADE presentation on UCAVs showed a future Indian UCAV (2015) with no tail (MCA design), a non-conventional wingform, and a 3 axis TVC.

10. OK, some nos....

Fan - Successful tests at CIAM
Compressor: (nos in brackets are design values)

6 stage axial flow, 3 stage variable vanes with IGVs.
Corr. tip speed ~370 m/s
Inlet diam: 590 mm

Mass flow: 24.13 kg/s (24.3)
Pressure: 6.42 (6.38)
Efficiency: 85.4% (85%)
Surge %: 21.6 (20% designed)

Combustor:
Has undergone aero testing at CIAM
K8 V4 combustor is close to design.

Turbine:
Pressure = 3.6
Mass flow function= 1.1
Isentropic eff = 85%
Max. TET = 1700K

Is a success, has met design.

11. Future uses:

Navy - KMGT - 1 MW for small ships being developed, 5-6 MW KMGT is a sucess and runs on Diesel, instead of the usual kerosene aviation fuel.

The railways also wants a 7-8MW CNG run engine, which will be a challenge in terms of fuel supply, rather than teh combustion itself, which shouldn't be a problem.


Any qns???

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Re: Kaveri & aero-engine discussion

Postby merlin » 11 Feb 2009 20:23

Solid gold 8)

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Re: Kaveri & aero-engine discussion

Postby Katare » 11 Feb 2009 21:59

Awesome info!!!

Thanks to GTRE! You guys tried!

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Re: Kaveri & aero-engine discussion

Postby SaiK » 11 Feb 2009 22:51

Honeywell offers engines for IAF’s Jaguar aircraft

========
good post there K Mehta.. thanks.
9. When asked where we lack, he mentioned 4 key areas

a. BLISK - integrated single Blade and Disk
b. Single Crystal blades - he categorically said - We do not have that tech at all.
c. Thermal Barrier Coatings - TBC - very critical for high temp engine operation. A talk on this by an American Indian prof attracted a house full audience. He mentioned that this is highly critical and export controlled, so they dont have it.

Glad to know a,b,c are under some kind of r&d.. and TVC is not per LCA requirements, perhaps MCA or UCAV.

Good.. we need more investments here. Hope the future belongs to GTRE reving up!

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Re: Kaveri & aero-engine discussion

Postby kobe » 12 Feb 2009 05:33

while K. Prasad report (via mr. mehta) is laudable in its detail of reasons for failures of kaveri engine and other related background issues, i think too much sensitive information is being made public to make a scapegoat out of GTRE.

even "democracies" don't reveal their strengths and weaknesses in such great detail out in public domain (for example, in USA government funded defense labs (e.g.los alamos) don't talk much in public), while private players (lockheed martin, etc) have corporate secrets.

it seems only in india and only this kaveri engine team has been brought to limelight for public flogging, and that in all gory details.

it can easily give china its next chess move (for example blackmail the french into not giving the jet engine tech to india)

even BARC got away with years of delays and "failures" to come up with a nuclear reactor for the submarines, and there are other examples. I wonder why only GTRE had to be blacklisted for things that were either not in their control or were pushed around by IAF into designing something that could not be tested or funded appropriately.

My theory is that for years GTRE/DRDO had made loud public pronouncements based on paper specs and raised the expectations way too high, and when they could not deliver, DRDO conveniently made a scapegoat out of GTRE and passed the buck at the expense of revealing india's strengths and weaknesses in the key technology area.

after reading the detailed post of prasad, I actually sympathise with GTRE and they should be encouraged to show their achievements and they should be funded appropriately and be supplied with the right infrastructure to forge ahead and implement all that they have learned from past failures for a new engine for MCA, otherwise the lessons learned will go to waste. remember, no text book exists on how to design a fighter plane's jet engine. it is an art form and it needs to be cultivated.

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Re: Kaveri & aero-engine discussion

Postby ragupta » 12 Feb 2009 06:10

after reading the detailed post of prasad, I actually sympathise with GTRE and they should be encouraged to show their achievements and they should be funded appropriately and be supplied with the right infrastructure to forge ahead and implement all that they have learned from past failures for a new engine for MCA, otherwise the lessons learned will go to waste. remember, no text book exists on how to design a fighter plane's jet engine. it is an art form and it needs to be cultivated.


Agree 100%.

With limited funding and incomplete infrastructure, cutting edge technology development is going to be painfully slow and most likely not achieve its goal.

While all Defence and Finance ministry say that there is no limit of fund for armed forces, India is not ready to spend money for relevant technology infrastructure, nor support people who are risking their career to work for national projects.

Hope that lesson will be learned from this project and course correction done. Fortunately, that appears to be the case with Snecma being contracted for further development of Kaveri engine.

They should also go ahead and create infrastructure similar to what they had access to in Russia to valuable time is not wasted in future.

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Re: Kaveri & aero-engine discussion

Postby NRao » 12 Feb 2009 06:18



That is ancient news. I had posted from HW web site - they made in the offer as early as 2006 or thereabouts.

Glad to know a,b,c are under some kind of r&d.. and TVC is not per LCA requirements, perhaps MCA or UCAV.

Good.. we need more investments here. Hope the future belongs to GTRE reving up!


Perhaps you missed "as dead as government servants"? The funds seem to be there. Magar ......................."Govt has not given funds, babus have sat on them."

GoI needs to go paperless and have work-flow with time out installed.

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Re: Kaveri & aero-engine discussion

Postby ragupta » 12 Feb 2009 06:25

GoI needs to go paperless and have work-flow with time out installed

yes please, this should be top priority. Every delay has to be explained and those responsible should be pulled for it, and habitual delayers should be fired. This will cut down on corruption to a large extent.

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Re: Kaveri & aero-engine discussion

Postby vasu_ray » 12 Feb 2009 12:37

Thanks K Prasad and Mehta for the latest on the engine, as long as you are entertaining questions,

is there a possibility of building similar engines for Nirbhay and Sitara which are in the <50Kn thrust zone? It was stated earlier that Nirbhay engine's was gong to be a foreign collaboration?

Assuming there is a core tech base here, is there a plan to integrate Ramjet propulsion with a turbo jet engine?

if TVC was at least thought about, how about super cruise?

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Re: Kaveri & aero-engine discussion

Postby shiv » 12 Feb 2009 19:06

K Mehta wrote:X-posting from AI-09 thread
k prasad wrote:Ok.... this is the GTRE story - (someone come up with sad music plz).... from the Aeroseminar.

11. Future uses:

Navy - KMGT - 1 MW for small ships being developed, 5-6 MW KMGT is a sucess and runs on Diesel, instead of the usual kerosene aviation fuel.

The railways also wants a 7-8MW CNG run engine, which will be a challenge in terms of fuel supply, rather than teh combustion itself, which shouldn't be a problem.


Any qns???


Thanks

Based on this I had a chat with a bloke at the GTRE stall.

As pointed out earlier, the Kaveri is more or less ready, but will not develop the power needed for a fully combat ready LCA. The LCA will fly with the Kaveri though.

For more power one of the things needed is higher temperatures in the core and we currently do not have the technology to create the materials that withstand higher temperatures.

Contrary to what someone had said (to me) after AI 07 we do not have the tech to fashion usable single crystal blades.

As stated in the post above - the marine engine is fine and "it has been proposed" that the core should remain as a "core" (metaphorically speaking) to develop engines for new applications. One possibility is UAV engines. Since UAVs are newish few are willing to part with the tech currently and having an engine is a bargaining chip if nothing else.

Hopefully the core really is used for other apps.

The twin engine MCA had a wind tunnel model (I took a pic) and the name "Kaveri" was mentioned. I specifically asked if the IAF was involved in making specs for the MCA and the answer was affirmative.

We live in hope..

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Re: Kaveri & aero-engine discussion

Postby Kailash » 12 Feb 2009 19:34

shiv wrote:The twin engine MCA had a wind tunnel model (I took a pic) and the name "Kaveri" was mentioned. I specifically asked if the IAF was involved in making specs for the MCA and the answer was affirmative.


Thats good news, coming from IAF. Would it be possible to upload the pic?

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Re: Kaveri & aero-engine discussion

Postby Victor » 13 Feb 2009 10:25

I am speculating here but slower dedicated attack aircraft like A-10 & Su-25 which IAF does not have may not require engines as demanding as those of a multi-role aircraft like LCA. If the existing Kaveri can do a good job within its current technical limits (single crystal blades etc), why not design an aircraft for the engine instead of the other way around. That would give GTRE some leverage to ramp itself up without having to go on its knees.

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Re: Kaveri & aero-engine discussion

Postby kit » 13 Feb 2009 11:48

Victor wrote:I am speculating here but slower dedicated attack aircraft like A-10 & Su-25 which IAF does not have may not require engines as demanding as those of a multi-role aircraft like LCA. If the existing Kaveri can do a good job within its current technical limits (single crystal blades etc), why not design an aircraft for the engine instead of the other way around. That would give GTRE some leverage to ramp itself up without having to go on its knees.


Build a house around the kitchen ? is that a good idea ? if you want to prove a jet engine wouldnt there be other options ?

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Re: Kaveri & aero-engine discussion

Postby Singha » 13 Feb 2009 11:56

it is said the americans first make a huge engine then wrap a a/c around that.
the euros go the other way around. both can work, provided you have good skills in both areas. unfortunately we are probably still a decade away from the leading edge in materials and tools so its a no-can-do indigenously at the moment.

license producing a bideshi engine and learning bits and pieces from it is onree
option at this point. we will never build a indigenous engine down this route ofcourse.

the real attack must come from beefing up materials & aerospace depts in all the
leading instts of national importance and giving them lots of projects and free use of the drdo facilities and labs. simultaneously gtre can be asked to scale kaveri down for cruise missile and UAVs and improve the fuel consumption. out of many small projects and engines, the Phoenix will rise again one day.

by then perhaps most UCAV/planes would use two smaller engines than one big engine.

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Re: Kaveri & aero-engine discussion

Postby vasu_ray » 13 Feb 2009 14:05

Considering these 2 data points,

GTRE says 90% of Kaveri design power is realized
Austin's table on payload vs range as it applies to a cruise missile

Assuming the scale down in engine size/weight and thrust efficiency is somewhat linear for a given cruise missile spec, the engine weight can be borrowed from the payload without compromising on the range too much

lets watch and see when Arun's Nirbhay specs come out on why a foreign JV for the engine was proposed?

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Re: Kaveri & aero-engine discussion

Postby KiranM » 13 Feb 2009 15:30

Victor wrote:I am speculating here but slower dedicated attack aircraft like A-10 & Su-25 which IAF does not have may not require engines as demanding as those of a multi-role aircraft like LCA. If the existing Kaveri can do a good job within its current technical limits (single crystal blades etc), why not design an aircraft for the engine instead of the other way around. That would give GTRE some leverage to ramp itself up without having to go on its knees.


Kaveri's current design has a low bypass ratio. CAS platforms are desired to have long loiter time and perform well in the subsonic regime. For this we need an engine with high bypass ratio.

The Kabini core can be used to develop such an engine perhaps.

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Re: Kaveri & aero-engine discussion

Postby SaiK » 13 Feb 2009 21:09

well they reported in 1999 this:-
http://www.drdo.org/pub/techfocus/aug1999/products.htm
pin1.gif (1016 bytes)Directionally Solidified & Single Crystal Turbine Blades & Vanes

A state-of-the-art gas turbine aerofoil component sometimes works in an environment of temperature beyond even the melting point of the alloy used for manufacturing it. These superalloy components possess a complex aerofoil geometry and are investment cast to equiaxed component or columnar grained or single crystal components by directional solidification to increase the performance. The technologies for both equiaxed and columnar grains or single crystal have been indigenously developed and demonstrated by DRDO for a variety of components. In the directional solidification, a bottom open ceramic shell mould is placed on a water cooled copper plate mounted on a ram shaft and is heated by an in situ mould heater in a vacuum casting furnace to a temperature beyond the melting point of the alloy to be cast. When the melted alloy is poured into the mould the alloy at the copper plate gets chilled and a columnar grained structure develops in the direction of heat extraction. The solidification proceeds into the mould cavity when the mould is lowered out of the mould heater. To produce a single crystal structure, some constriction ahead of initial columnar grain structure that allows growth of only one of the grains of the columnar structure, usually a helix with about one turn, is used.

Leachable fused silica cores are used for casting aerofoils to very tight tolerances with complex internal cooling passages characterised by thin walls of the order of 0.5 mm. The shell and core system is designed so that no distortion occurs at the temperature of directional solidification of about 1500 oC.

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Re: Kaveri & aero-engine discussion

Postby SaiK » 14 Feb 2009 07:43

Image
EJ200 The turbo fan blade design matches GE's latest designs (that was posted here), for bird hit and more air intake for higher thrust.

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Re: Kaveri & aero-engine discussion

Postby Raj Malhotra » 14 Feb 2009 10:08

IF M-88 core can be upgraded to 90kn in a JV from 75kn then if the Kaveri core was sound then it could also have been upgraded to 90kn from 80kn design. All engines are built with future growth prospect of around 15-40%, the only reason kaveri core cannot improve is perhaps it is a disaster and GTRE is going to declare it a success and close it. Indian tax payer's money will just help the French

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Re: Kaveri & aero-engine discussion

Postby vina » 14 Feb 2009 10:48

Problem is that with current materials, Kaveri cannot deliver 90KN or so efficiently. The Kaveri core with current materials is inherently thermodynamically less efficient than an engine with more up to date materials. That is the bottomline. Yeah, you can scale the Kaveri, but the problem is it wont be efficient and it will be a bloated engine with a low thrust to weight ratio.

No one will sell you the materials alone . The option is get the French core or get your own materials upto the level of competition. There really is no alternative to increasing the Turbine inlet temperature. This is as far as you can go with the current level of materials technology.

You need better thermal barrier coatings and single crystal blades to go forward.

Kaveri's thermodynamic cycle configuration too is off and wont work . The bye pass ratio of 0.16 is too low. That is what the Eurojet 200 guys too gave as the feedback when they were invited to review it (from the comments those guys made in the press) and a more "modern" thermodynamic cycle is needed with bye pass ratio closer to 0.4 or so. This will mean an engine with higher mass flow rates as well, something the Kaveri core was not designed for. I think the M88 core has the growth potential to be scaled and that is the difference, with just the mass flow rate increasing to deliver the thrust growth, with largely similar TSFC. With Kaveri, the problem is the thermodynamics have to change and that means a fundamental change and really a "new" core.

just my guesses and all the rest of it of course.

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Re: Kaveri & aero-engine discussion

Postby Atri » 14 Feb 2009 17:58

Armen T wrote:If it actually flies, then that figure is quite possible actually. Most IRBMs missiles exceed Mach 15+. Agni II is officially listed to have a top speed of 5-6 km/sec (ref: 1 and 2).

5 km/sec = 5000 m/sec
6 km/sec = 6000 m/sec
Speed of sound = 330 m/sec approx.
Therefore Agni II hits a top speed between mach 15+ and mach 18+

References:
http://en.wikipedia.org/wiki/Agni_missile_system
1. BRF PDF page on long range missiles


Cross posting from Indian Non-response to Mumbai attackes thread in strategy forum.

Gurus, This may be a naive question, but please answer....

From what I could understand by reading this thread is that India cannot produce material which can withstand high temperatures required for higher thrust in kaveri engines.

From this post, we understand that Agni is capable of producing producing 502 KN of thrust. But since it uses solid fuel, its irrelevant. Prithvi Engine uses liquid fuel and generates very high thrust as well.

I guess, every thing in Prithvi and Agni series of missiles is made indigenously, including engines. If we know the engines which are made up of materials which are used to make engines that generate this high thrust subsequently means that those materials can withstand that high temperatures... That means, in principle, we have the materials which can withstand high temperatures.

Why can't we use that material to build kaveri engine? If a material can with stand the temperatures resulting in engines of Prithvi/Agni or GSLV/PSLV, why can't the same material be used as it is or with slight modification to withstand the temperatures in kaveri engine? After all, the thrust required for a best of jet engines in world is definitely less than one required for rocket as big as GSLV..

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Re: Kaveri & aero-engine discussion

Postby shiv » 14 Feb 2009 18:05

Chiron wrote:
Cross posting from Indian Non-response to Mumbai attackes thread in strategy forum.

Gurus, This may be a naive question, but please answer....

From what I could understand by reading this thread is that India cannot produce material which can withstand high temperatures required for higher thrust in kaveri engines.

From this post, we understand that Agni is capable of producing producing 502 KN of thrust. But since it uses solid fuel, its irrelevant. Prithvi Engine uses liquid fuel and generates very high thrust as well.

I guess, every thing in Prithvi and Agni series of missiles is made indigenously, including engines. If we know the engines which are made up of materials which are used to make engines that generate this high thrust subsequently means that those materials can withstand that high temperatures... That means, in principle, we have the materials which can withstand high temperatures.

Why can't we use that material to build kaveri engine? If a material can with stand the temperatures resulting in engines of Prithvi/Agni or GSLV/PSLV, why can't the same material be used as it is or with slight modification to withstand the temperatures in kaveri engine? After all, the thrust required for a best of jet engines in world is definitely less than one required for rocket as big as GSLV..



Good question - I am not the expert but I will answer to the limits of my knowledge.

A rock - say a lump of granite could withstand higher tempteratures than a lump of steel before melting. But a rock would be no good as a turbine blade in its ability to withstand the mechanical stresses.

So a non moving component in a rocket engine could be a material that does not have to withstand mechanical stresses like a jet engine blade. the latter must be able to withstand heat and mechanical stresses.

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Re: Kaveri & aero-engine discussion

Postby shiv » 14 Feb 2009 18:08

kit wrote:
Build a house around the kitchen ? is that a good idea ?


But if the engine is proven, an aircraft can be built around the core engine. Build in a higher bypass ratio and use it for a transport aircraft.

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Re: Kaveri & aero-engine discussion

Postby Raj Malhotra » 14 Feb 2009 21:16

Thanx for a detailed answer. Am not a techno but I posted around 10 years ago on BRF that some people who have spent whole life on turbines are saying that GTRE has got the basic design wrong and their only competence is to design the outer cover of the engine and that is also a may be!

Anyway, if Kaveri is even say limited then why not order 200 AJT-LIFT versions of LCA with indigenous Kaveri core and when we get tech / comptence in single crystal blades/thermal barriers then we can uprate it.

vina wrote:Problem is that with current materials, Kaveri cannot deliver 90KN or so efficiently. The Kaveri core with current materials is inherently thermodynamically less efficient than an engine with more up to date materials. That is the bottomline. Yeah, you can scale the Kaveri, but the problem is it wont be efficient and it will be a bloated engine with a low thrust to weight ratio.

No one will sell you the materials alone . The option is get the French core or get your own materials upto the level of competition. There really is no alternative to increasing the Turbine inlet temperature. This is as far as you can go with the current level of materials technology.

You need better thermal barrier coatings and single crystal blades to go forward.

Kaveri's thermodynamic cycle configuration too is off and wont work . The bye pass ratio of 0.16 is too low. That is what the Eurojet 200 guys too gave as the feedback when they were invited to review it (from the comments those guys made in the press) and a more "modern" thermodynamic cycle is needed with bye pass ratio closer to 0.4 or so. This will mean an engine with higher mass flow rates as well, something the Kaveri core was not designed for. I think the M88 core has the growth potential to be scaled and that is the difference, with just the mass flow rate increasing to deliver the thrust growth, with largely similar TSFC. With Kaveri, the problem is the thermodynamics have to change and that means a fundamental change and really a "new" core.

just my guesses and all the rest of it of course.

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Re: Kaveri & aero-engine discussion

Postby vina » 14 Feb 2009 22:25

Chiron wrote:..Prithvi Engine uses liquid fuel and generates very high thrust as well.

Why can't we use that material to build kaveri engine?


Rocket engines work for a few minutes and are single use. Surely unless you want the pilot to go on a kamikaze mission, a single use engine wont do for a plane. Plus rockets are different from air breathing jets. Rockets don't have turbines to extract energy from the exhaust and turn a compressor. Jets do.

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Re: Kaveri & aero-engine discussion

Postby SaiK » 14 Feb 2009 22:33

vina, good points. hope GTRE folks gets more open reviews and start on the correction course. we can only do things when we have some money. its time GTRE buckles up!

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Re: Kaveri & aero-engine discussion

Postby Victor » 14 Feb 2009 22:43

Raj Malhotra wrote:
Anyway, if Kaveri is even say limited then why not order 200 AJT-LIFT versions of LCA with indigenous Kaveri core and when we get tech / comptence in single crystal blades/thermal barriers then we can uprate it.

Exactly. We are making the "good" an enemy of the "perfect" and ending up with neither. If GTRE can become a revenue generator instead of only an expense item, it could create some autonomy for itself to do more of the things that need to be done. 50 years ago, GTRE had shown a near-cutting edge competence and sophistication that must have scared the goras, and its capabilities have been steadily eroded since then. It is critical to prevent a total write-off which it seems is imminent. The very structure of GTRE needs to change.

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Re: Kaveri & aero-engine discussion

Postby Atri » 14 Feb 2009 23:06

vina wrote:
Chiron wrote:..Prithvi Engine uses liquid fuel and generates very high thrust as well.

Why can't we use that material to build kaveri engine?


Rocket engines work for a few minutes and are single use. Surely unless you want the pilot to go on a kamikaze mission, a single use engine wont do for a plane. Plus rockets are different from air breathing jets. Rockets don't have turbines to extract energy from the exhaust and turn a compressor. Jets do.


I guess you got me wrong.. I did not say about using rocket engines in planes. I asked about using the material which is used to make rocket engines to be used in kaveri jet engines.. That material/metal alloy of which Prithvi OR GSLV engines are made up of can withstand high temperatures, which is the basic problem of the material that Kaveri engine is made up of.. If we use that same alloy to build kaveri jet engine, could we solve the temperature problem, this was my question..

I guess, Shiv ji explained it in a better way...

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Re: Kaveri & aero-engine discussion

Postby Kailash » 14 Feb 2009 23:55

Chiron wrote:I guess you got me wrong.. I did not say about using rocket engines in planes. I asked about using the material which is used to make rocket engines to be used in kaveri jet engines.. That material/metal alloy of which Prithvi OR GSLV engines are made up of can withstand high temperatures, which is the basic problem of the material that Kaveri engine is made up of.. If we use that same alloy to build kaveri jet engine, could we solve the temperature problem, this was my question..

I guess, Shiv ji explained it in a better way...


It is sustained exposure to those temperature, endurance, toughness, predictable failure stresses/strains and various other mechanical properties which determine material selection. There are chemical aspects like corrosion resistance too to be considered for naval usage.

Though we have developed C-C composite heat shields etc, those cannot substitute for metallic alloys in every situation. Shiv's explanation was very apt in this respect. If weight and strength were the only parameter, world would be building all composite aircrafts!

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Re: Kaveri & aero-engine discussion

Postby vasu_ray » 14 Feb 2009 23:59

All from wiki sources,

Embraer , Global Hawk uses 1 engine
Powerplant: 2× Rolls-Royce AE 3007A turbofan, 33.0 kN (7,420 lbf) each
Thrust-to-weight ratio: :1

Sitara
Powerplant: 1× Snecma Larzac or Al-55I , 14.1 kN or 17kN (3,170 lbf or 4,500 lbf)

Hawk, Jaguar uses 2
Powerplant: 1× Rolls-Royce Adour Mk.951 turbofan with FADEC, 29 kN (6,500 lbf)
Thrust-to-weight ratio: 4.725:1

Kaveri
Military thrust (throttled):11,687 lbf (52.0 kN) 13,500 lbf (60.0 kN)
Thrust-to-weight ratio: 7.8 (76.0 N/kg)

Other than GTRE being "another PSU", I don't see a reason why these engines cannot be derived here? and focus on cutting down development lead times and maintenance issues of these foreign engines

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Re: Kaveri & aero-engine discussion

Postby smata » 15 Feb 2009 02:32

Cheers
Last edited by smata on 15 Feb 2009 21:45, edited 1 time in total.

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Re: Kaveri & aero-engine discussion

Postby Arun_S » 15 Feb 2009 03:58

shiv wrote:As stated in the post above - the marine engine is fine and "it has been proposed" that the core should remain as a "core" (metaphorically speaking) to develop engines for new applications. One possibility is UAV engines. Since UAVs are newish few are willing to part with the tech currently and having an engine is a bargaining chip if nothing else.

I think Kaveri for UAV will not fly. Too much thrust, and low bypass jets are not high on SFC.
UCAV maybe.
Kaveri footprint is in middle limbo neitherland, (like Dhruv for Navy), tad too big for UCAV and too small for LCA-Mk II.

The best fit I can think of is for large high altitude UAV for which a slightly scaled down Kaveri with higher bypass ratio will fit well.

Hopefully the core really is used for other apps.

The twin engine MCA had a wind tunnel model (I took a pic) and the name "Kaveri" was mentioned. I specifically asked if the IAF was involved in making specs for the MCA and the answer was affirmative.

We live in hope..

This I think is the best hope because this will fit Kaveri both for thrust and weight.
But that is till some fly-by-night suger daddy comes and sell the need for a MCA with bigger wing and payload capability for which (by then) IAF's standard F414 engine will fit so nicely :rotfl:
Can GTRE and ADA hire some gora lobbyists who are now jobless in New York to sell Yindian Kaveri to the Yindian Goberment / MoD /IAF ? That me think is Kaveri's best bet. !

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Re: Kaveri & aero-engine discussion

Postby vasu_ray » 15 Feb 2009 07:35

The numbers seem to say these turbofans vary between power and endurance, while GTRE has reached the lower bounds of the niche segment in power regime, we haven't seen the niche in endurance yet, perhaps the Nirbhay's engine JV is for that reason, as do use of propellers for current generation of UAVs.

There is a big enough playing field for GTRE and the forces between these two niches.

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Re: Kaveri & aero-engine discussion

Postby Kailash » 15 Feb 2009 18:29

If lesser power is Kaveri's only problem (assuming that the breaking of blades etc are fixed), then after running some endurance tests, cant we market Kaveri to engine upgrade programs around the world?

Kaveri should be able to beat the cost and power rating of GE-404 anytime.

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Re: Kaveri & aero-engine discussion

Postby shiv » 15 Feb 2009 19:06

Kailash wrote:If lesser power is Kaveri's only problem (assuming that the breaking of blades etc are fixed), then after running some endurance tests, cant we market Kaveri to engine upgrade programs around the world?

Kaveri should be able to beat the cost and power rating of GE-404 anytime.


The idea is good but Aero Engines live on reputation.

Nobody wants an engine that is not tested and proven.

For example - engines like the civilian CFM 56 are regularly recoded as running (collectively) for periods in excess of 10 million hours of flight without a single failure.

That record is not easy to reach. If and when Inda gets there - India will be a leading jet engine manufacturer in the world. That is like running an engine 24x7 for 3 years in a row.

The Kaveri of course is a military engine (currently) and is probably put under greater strain - but the fact that it can withstand that strain and that an Indian company can ensure good back-up should become well known. The last thing you want is an engine failure in a plane. Naturally people tend to favor that which is proven.


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