Kaveri & Aero-Engine: News & Discussion

[chackojoseph]

No Kabini Core. Snecma Core is not going to be used.

Thanks CJ. Apparently no one refuted the post in the previous page.

Thij ij bhy i said "truth about K-10."

Then what is the collab with Snecma about?

Added later: Ok. So it is the SCBs we are after.

One of the tech.

[chetak]

Kaveri engine dosen't has a problem per say except a particular area in the core. The materials are not able to withstand heat and have weight. So the K-10 will have Kabini core being modified for heat handling. DRDO is proposing to buy off the technologies and help in adapting it to the Kabini core.

DRDO wants to learn from this. K-10 will have heat areas (like SC blades) attended to in Kabini as well as weight management. Thrust will be increased.

So, DRDO will learn, engine will be produced and Snecma will get its share of the money.

And the concerned trained people will smartly migrate to industry, citing excuse of father sick!!

[vina]

Kaveri engine dosen't has a problem per say except a particular area in the core. The materials are not able to withstand heat and have weight. So the K-10 will have Kabini core being modified for heat handling. DRDO is proposing to buy off the technologies and help in adapting it to the Kabini core.

DRDO wants to learn from this. K-10 will have heat areas (like SC blades) attended to in Kabini as well as weight management. Thrust will be increased.

So, DRDO will learn, engine will be produced and Snecma will get its share of the money.

Refer to the sermons in Pinglish by El-Enqyoob-Al-Gas-Turbiney many many moons ago on this topic and the mashawr-e-aam on this.

I do think that the core is a "oversized" , ie pye-bass is too low and while there is high specific thrust, the total thrust suffers because of that. Pye-bass needs to go up.. either Kabini goes tinku and chikna or the Yell-Pee spool needs to grow bigger to handle a higher mass flow to handle to make the pye-bass halaal and get the thrust of the engine up..

Sure, if you are going to decrease core flow and increase pressure ratios there, you need a higher TeT and the need for the materials from Frogistan.

[vina]

And the concerned trained people will smartly migrate to industry, citing excuse of father sick!!

Atleast, when the vishit massage "Led Rips Massage Palouls " in LalBatti Sadak Islamabad, they can afford to pay on their own!

[Neela]

I do think that the core is a "oversized" , ie pye-bass is too low and while there is high specific thrust, the total thrust suffers because of that. Pye-bass needs to go up.. either Kabini goes tinku and chikna or the Yell-Pee spool needs to grow bigger to handle a higher mass flow to handle to make the pye-bass halaal and get the thrust of the engine up..

Sure, if you are going to decrease core flow and increase pressure ratios there, you need a higher TeT and the need for the materials from Frogistan.

If bye-pass needs to go up, then I would also assume that inlet sizes and overall diameter will also be increased,no?

[arunsrinivasan]

Refer to the sermons in Pinglish by El-Enqyoob-Al-Gas-Turbiney many many moons ago on this topic and the mashawr-e-aam on this.

Where is El-Enqyoob-Al-Gas-Turbiney ? I miss his posts

[Neela]

Refer to the sermons in Pinglish by El-Enqyoob-Al-Gas-Turbiney many many moons ago on this topic and the mashawr-e-aam on this.

Where is El-Enqyoob-Al-Gas-Turbiney ? I miss his posts

I have it bookmarked. You will have to wait for 6 hours before I can post it to you.

[arunsrinivasan]

@ Neela thanks for the offer, please do post them for reference. I wanted to know why Al-Enqyoob doesnt post now. He seems to have left BR ...

[Neela]

@ Neela thanks for the offer, please do post them for reference. I wanted to know why Al-Enqyoob doesnt post now. He seems to have left BR ...

Do not think you will thank me after reading that post. It is 400% pinglish! Initially it was fun but when you start to really read it to understand the details, you will find it quite annoying.
IIRC, it was after this post that Ramana & co banned Pinglish to the happy lands of BENIS!

[arunsrinivasan]

Thanks. Is that why Al-Enqyoob leave BR? His insights on the kaveri was very valuable for lesser mortals like me. Sorry OT.

[Surya]

Thanks. Is that why Al-Enqyoob leave BR?

No - and lets leave it at that

[tejas]

If SNECMA sells DRDO the tech. to allow the final piece of the Kaveri puzzle to fit that is more than worth the price of the Rafale as it gives India independence wrt so many weapon sysytems. AOA.

[vic]

Kaveri engine dosen't has a problem per say except a particular area in the core. The materials are not able to withstand heat and have weight.

I hope you appreciate that the aforesaid refers to 90% of the high end tech in an engine?

[chackojoseph]

Kaveri engine dosen't has a problem per say except a particular area in the core. The materials are not able to withstand heat and have weight.

I hope you appreciate that the aforesaid refers to 90% of the high end tech in an engine?

LoL, you are right. But, you have singled it out.

[Singha]

even if the new proposal works , the euros will still continue to have a hand and make decent money off production kaveri or its successors. thats because plenty of parts are imported , incl some from hispano-suiza of spain.

its ok I think, because these are friendly nations and as long as the overall design and integration is owned by us, eventually even korean and japanese aerospace industry can be tapped as they mature to euro levels, if we cannot make some parts locally.

[SaiK]

accelerated approach could perhaps give a booster to K. Along with new setup for GATET, components and subs, experiences gained grumov must be transferred on to a local small scale facility to test engines on UAVs, UCAVs, and trainer a/cs.

I guess, investments is the bigger issue. A modified setup, could clean GTRE bad names, and re-establish DRDO's new look on turbine high altitude test facility.

keep finger crossed for such a news to happen in the near future.

[maitya]

Thanks. Is that why Al-Enqyoob leave BR? His insights on the kaveri was very valuable for lesser mortals like me. Sorry OT.

Yes, Suryaji is right, let the sleeping dogs lie - it's bad karma to get entangled into various planetary and celestial stuff.

However, here are few relevant excerpts from some of my old posts on what N^3 was alluding to - they are still very relevant IMO.

Long back, N^3 (or was it vina) alluded, in his own piglish with multi-layered-hidden-logic style, that this mass-flow problem can be atleast partially solved by improving the aero-dynamic efficiency of the LP compressor itself - now when this is contrasted with an very old news of GTRE failing to get the required foreign collaboration in manufacturing the designed complex-geometry-LP-compressure blades (which *may* have resulted in them settling for an sub-optimal soln), it does raise a question if this new "process technology" is more about LP compressor and it's pressure ratio related or not?

But having said that let's do some introspection shall we:
From a layman's point of view, the design level dry thrust (52KN) was achieved but it failed on wet thrust (achieved 65KN as opposed to 81KN).
And this is direct result of a reduced massflow within the engine 24.3kg/s (while the design goal was 78kg/s).

Now as the thrust depends on velocity of the gases and the mass of those gases, the thrust can be increased by increasing the quantity of the gas flow or by increasing the speed of the gas flow.
The type of nozzle mass flow (sum total of afterburner entry mass flow plus the effective afterburner fuel flowrate) required is just not possible to achieve as the afterburner entry mass flow is just too low in the 1st place (there is only so much of fuel that can be added).

So, the only option is to increase the mass flow rate to solve this wet thrust problem - Vinaji brings an interesting observation, reduce the volume of the core itself so that the mass-flow rate can be increased. Others will say, do that by inventing/getting/ToTing blisk manufacture/SCB tech so that the TeT can be increased.

But I'd still like to remind what Al Enqyoob-ud-din-e-Gas-Turbine once told us:

narayanan wrote:
It's a lot better than that. Note that stage pressure ratio for Kaveri is onbly about 1.3. Long way to improve, and this does not require SCB. Just good aerodynamics, or maybe just good fabrication of the existing design (based on other things I've seen, I suspect strongly that the actual fabrication quality control is where they lose 50% of their design performance). If they can get even this improved, they can probably save a lot of weight on the engine. Or they can beef up the turbine blades with the saved weight, or add cooling and increase T.i.T.

Also, the T.i.T is still a long way from getting to the levels where SCB is needed.

IOW, a number of small improvements, whose cumulative effect is a drastic improvement. Just plain hard work and good management and coordination.

[Neela]

Original post is here:

http://forums.bharat-rakshak.com/viewto ... 34#p723334

[ramana]

The Aviation Week article in LCA thread has some info on progress of kaveri test regime and plans for its future usage.

[vina]

Hmm let me do some good ol speculation /reading between the lines/connecting the dots here.

1) The Kaveri bye pass ratio is very low indeed. Need to get that up to around 0.3 to 0.65 range for improved thrust and fuel economy

2) With that kind of bypass reported, the core flow is indeed large.

3) Any Kaveri that comes about will be used only for an MLU of the Tejas MKI /MKII and the MKII will debut with a 100KN GE engine which caters for a higher flow. An MLU engine with the inevitable weight gain will need around 110 to 120KN minimum.

4) The AMCA project as it stands will need two 120KN range engines for sooper dooper cruize and all that jazz.

5) Chacko says current Kabini core will use Frogistan Materials and the eco core is not going to be used.

6) An eco core Kaveri can generate 90KN tops.. No way it will power a MKII or an MLU'ed one and will be rather wimpy for the AMCA.

So putting together all this I think, we are looking at GTRE coming up with a 120KN class engine with Frogistan materials in the Kabini core and a higher mass flow LP spool than the current Kaveri topping it up.

Will fit in perfectly with the kind of flow rates the F414-INS6 will need in the MKII and similar size and dia.

So there it is folks, this seems to be the scenario that will square the circle and possibly explain all the permuations and combinations of situations.

[Singha]

the jaymahal incident is perhaps an opportunity (cover) to clean out any further such "issues" in GTRE and tone it up for the next decade. the AMCA will need a engine around 2020 first flight, so the new engine if any has to be undergoing flight tests by 2015 to get 5 yrs to test it fully, fine tune it and make it reliable...a new airframe cannot fly with a new unproven engine.

else we will have to test the AMCA with a similar class engine like AL31 / 117 or even the redoubtable WS10d

[JTull]

the jaymahal incident is perhaps an opportunity (cover) to clean out any further such "issues" in GTRE and tone it up for the next decade. the AMCA will need a engine around 2020 first flight, so the new engine if any has to be undergoing flight tests by 2015 to get 5 yrs to test it fully, fine tune it and make it reliable...a new airframe cannot fly with a new unproven engine.

else we will have to test the AMCA with a similar class engine like AL31 / 117 or even the redoubtable WS10d

vina and Singha, you've hit the nail on it's head. We need a much higher thrust engine (than kaveri) and very soon (3-4yrs). This is why it is not a good idea to tie AMCA to a Kaveri derivative as we'd not have learnt from the LCA engine fiasco.

[Rahul M]

I don't quite see why we need much higher thrust engines than kaveri-snecma/ kaveri-2/whateveryoucallit. AMCA is supposed to be a 20 tonne jet, it is reasonable to assume that 20 tonne is the expected normal T/O weight with combat load. given projected kaveri-2 output @ 90kN IIRC that would give it a TWR at par with aircraft like f-22 and pakfa. why would we need more ?

[chackojoseph]

People also forget that its not variable thrust engine. The variable thrust is needed when the engine cannot perform at particular situation.

However, GTRE is expected to figure the thrust number based on what it is looking in NFGA.

[Singha]

the AMCA does look to be no bigger than rafale size which is around 20T MTOW - from the models shows in AI2011. if that be true, and given its strike orientation, even EJ200/F414 class (90-100kN) engines would suffice to give a respectable and effective T:W.
but expectations will surely rise in 10 yrs and more TW, less weight, more durability may be called for, less IR signature from the ground up too, plus the supercruise thing, lower SfC...goalposts are always moving. GE/Snecma are not sleep on the job but working on better things.

a AL31 class large engine would look a bit excessive for the AMCA seen in model unless we needed to prove a point with a airshow monkey that has twice the climb rate of a Mig25

[SaiK]

we can keep slipping boats, but we need to be on at least one boat, no matter how slow the boat is. planning to delivery, things can't be taken this lightly by program funders, stake holders and the end users.

Joining the bandwagon of GE/Snecma is a good idea, or just touch base with them and keep on the trail for most of the core technology, and source only to about 20% dependency. long term work on the goals.

I still say, we need to seriously look at establishments that are slipping especially on precision engineering, and provide the required assistance wherever it is needed.

[shiv]

1) The Kaveri bye pass ratio is very low indeed. Need to get that up to around 0.3 to 0.65 range for improved thrust and fuel economy

Is there a contradiction in design requirements here?

I recall reading a long time ago (and I am not sure) that the "low bypass" was to improve high altitude performance. However everything I read about engines tells me that bypassing is efficient and a high bypass engine will be economical.

But would such a high bypass engine produce rapid increases in thrust and acceleration at high altitude. Cruise is one thing, but acceleration is another thing. Don't high bypass engines carry far more inertia to acceleration while being more efficient?

Mind you I may be way off course in my assumptions.

[vina]

Is there a contradiction in design requirements here?
I recall reading a long time ago (and I am not sure) that the "low bypass" was to improve high altitude performance. However everything I read about engines tells me that bypassing is efficient and a high bypass engine will be economical.

Well, at altitude, the air is much thinner and you need far less thrust than while on the ground. So you are fine .

Yes, any engine's thrust will decrease with altitude, a lower bypass engine will retain higher proportion of thrust sure, but then, the most thrust (highest oomph) is needed at lower levels and at take off kind of situations.

But would such a high bypass engine produce rapid increases in thrust and acceleration at high altitude. Cruise is one thing, but acceleration is another thing. Don't high bypass engines carry far more inertia to acceleration while being more efficient?

Mind you I may be way off course in my assumptions.

With the kid of bypass ratios talked about here and not the 5 to 7 upwards in modern civil turbofans, where the inertia is due to the large fan mostly (infact in a GE-90 in a B-777, the fan dia is greater than the fuselage cross section dia of an old gen B-737!) and where the fan takes a couple of seconds to spool up to full thrust (think of it next time you fly.. the pilot puts on power at the take off point.. the engine note goes whinnnnnneeeeee and a couple of seconds nothing happens, then it surges forward and then a few seconds later, you are pinned back against your seat), the military higher bypass engine sure will take a little longer than a nearly pure low bypass engine like Kaveri (with the current 0.16 ratio), but not by much.

Refer to the original friday sermon by Al-GasTurbiney (link someone posted) .. Many of that was discussed, including "halaalness" or otherwise of how low bypass is for high mach numbers and why ramjets are halaal with 0% bypass per Madrassa , but with nai takneeks, the halaal-haraam mixture has changed towards haraam!

[Singha]

the P53 engine in M2k per my trustly old salamander book has a really low bypass (called a 'leaky turbojet') and maybe thats why its high alt - high speed regime is the core area .... it has trounced many a famous fighter the higher and faster the fight gets.

since the Tejas is supposed to be primarily A2A oriented with a secondary emphasis on strike (?) , I wonder if going that clean n simple M2k route is the best?

[Austin]

I recollect reading Janes in 90 where Tejas used to be portrayed as Air Defence Fighter with Secondary Strike Capability , but the way it is evolving and with range of weapons and electronic like mentioned by AW&ST , it would be any thing but secondary in that role , it would be a through-bred multirole fighter or a more cheesy term called "Omni Role Light Fighter" would be more appropriate

[Singha]

quoting from "modern fighters and attack aircraft" bill gunston :

M53 is almost a turbojet. its bypass ratio being very low and overall pressure ratio of only 9.3 showing the degree to which it is optimized to supersonic speed at very high alt. thus it is at a great disadvantage at fuel burn in the normal subsonic regime which accounts for more than 95% of even a mirage2000s flight time

- some maybe that explains the key to F16s combat radius of almost 900km on a small airframe - higher bypass ratio in the PW/GE engines ?

- and maybe thats why the M2k_N/D ground strike platforms needed those huge benis shaped fuel tanks underwing....

[vina]

- some maybe that explains the key to F16s combat radius of almost 900km on a small airframe - higher bypass ratio in the PW/GE engines ?

Per wiki chacha, the bypass ratio of the M53 and the PW-F100 is the same at 0.36 . However notice the difference in dry and also wet thrust for very similar engines (size wise the F100 is around 100kgs heavier) and also notice the far lower specific fuel consumption for the F100 (convert to same units for both..), the F100 has a far higher pressure ratio (32 or so per chacha..)

The GE F100 engines have a 0.76 odd bypass ratio , needing a higher airflow rate and having a higher thrust than the equivalent PW engines of similar vintage.

No wonder the difference in efficiency shows up in range and thrust ratings between the 2 spool Amirkhan engine and the single spool snecma.

[Singha]

so you are saying the PW-F100 is a more TFTA engine than M53 for that era ? ie lower sfc, higher dry and wet thrust....

and that made the original PAF F-16s a pocket rocket with long range strike and made delhi dhoti shiver like anything....? one must recall Pak was slated to receive upto 150-200 F-solahs....not just 40....pressler or someone else nuked that concept.

PAK was truly in position to receive massive amts of arms like Iran or Egypt if the soviet union and soviet occupation of afghanistan had lasted a few years longer....

the Mirage2000H could presumably rip the F-16-block15 apart higher than Mach1.5 at higher alts .. using lower wing loading and superior acceleration at those alts to climb and dive steeply , using speed and space to run away or chase down... since it could ramp to mach2.2 in short bursts ... but anything else would be a serious contest depending on radar (fortunately the RDM7 was likely better than the apg-xx of old) and missiles (530D > sparrow , 550 == aim9l maybe)

[vina]

and that made the original PAF F-16s a pocket rocket with long range strike and made delhi dhoti shiver like anything....? one must recall Pak was slated to receive upto 150-200 F-solahs....not just 40....pressler or someone else nuked that concept.

Indeed, if you go back to the mid 80s (84 to 86 time frame or so) when the PAF got the F-16s, Amirkhan also wanted to transfer AWACS (atleast EC2C if not E3 sentries) to Pakiland and that seriously set of dhoti shivers here. There is nothing available anywhere that India could have got access to that could have countered a Unkil transferred Awacs + F-16 combo.

Luckily, better sense prevailed with Unkil and the AWACS transfer never happened and the F-16 for fokat also didnt happen and the money that Mohtarma BB paid for the F-16s came back in the form of genetically modified soybeans or something (fit only for feeding to pigs really in anyplace) after nearly a decade ..

[shiv]

One sad story was of the Jaguar that went into a hillside in the Nilgiris - the pilot was unable to pull up, having dived into a valley. The Nilgiris hardly go over 8000 feet in height. What of the Himalayas that average something over 15,000 feet? An aircraft needs power to fly between valleys. I would have thought that absolute excess power in terms of a great T/W ratio and a low wing loading are advantages.

But what sort of engine is "ideal" for regular operations - both attack and air defence at altitudes of over 15,000 feet. the IAF is the only air force in the world (that I am interested in) with this unique requirement.

[Singha]

saar my wild opinion is:
- since you want air defence at 15,000ft+ , low wing loading is a must - this is separate from engine issue but related to your task
- depend on fbw to keep it stable in lo-lo-lo (rather than high wing loading)
- good T:W , more the better
- superb fuel consumption (efficiency of engine for any given thrust setting esp dry thrust) + low drag airframe / conformal weapons
- durability and uptime - more planes in the air
- good agility at subsonic and transonic speeds for air combat and climbing
- weather radar mode for main radar , TFR mode automatic, FLIR pod or internal , GCAS auto - identify and deal with blind weather conditions
- instrument landing system
- engine inlets that can deal with thin air flow yet capture enough air for optimum take off performance

Just a good engine cannot make a plan ideal, it has to be mated to a great airframe like F-solah or M2k.

[karan_mc]

This article did mentioned little higher figure of new Hybrid Kaveri rather then usually mentioned 90-95 kn , i am pretty much sure technical requirements for the engine are still not fixed and this is the reason why the JV has not gone through at .

ADA which is the prime development organisation of the Advance Medium Combat Aircraft is looking for an engine in 100 to 110 kn thrust range,

ADA is taking very similar approach like it did with LCA Project and will roll out first Technological Demonstrators (AMCA TD-1 and TD-2) in next 5 to 6 years and have first flight in next one year after the roll out. Experts believe that ADA might use GE Provided F-414IN engine which has been already selected by ADA to power Tejas MK-2 jets.

http://idrw.org/?p=2072#more-2072

[ramana]

Vian, Can the improved Kaveri be mated on the M-2Ks?

[Ryan Maguire]

<OT>
there is one interesting aspect(pardon my poor english if this is correct word) about engines testing - When Kaveri was tested at Indian test facilities, it passed certain test phases. When same tests were repeated in Russia, it failed consistently and Kaveri took many years and revisions to pass through those phases. Only after that, it entered in advanced testing onto FTB(plane).

Now, how difficult it is for someone, to simply modify test setup and set it to give abnormal results for few years?
</OT>

I think , people don't give much importance to testing facilities required for engines, which are part of 'development' efforts rather than something like testing software code before shipping to customers. In software code, if you write C=A+2, you know you will get exactly C=A+2, there is no energy loss involved here because its a definite system. Engines are different. Its non-digital, non-linear science. There is big difference between engine design on paper and actual behaviour in real. And, you can factor in those coefficients and deviation data only through tests. So, testing of engines is not same as testing in software/IT field, where its post-development activity. But rather its part of R&D. You make a engine design, you test, collect data and see if its close to your design data. If not, you redesign/modify/improve. Then you test again, collect data and this cycle is repeated till you get a certain required performance.

And, that's where Kaveri lost a full decade - due to lack of testing facilities within India. Imagine how difficult it would be for them to take all designers to Russia and setup whole design team there. And, then come back to India to implement every engine redesign/revision since Russia won't have factory for Kaveri there to make modified parts!

And now add the possibility which I enclosed above in <OT>. Whole picture is pretty scary!

Now, lets build those engine facilities here very fast...!

[NRao]

We have been through this discussion about testing facilities and my recollection is that they were found to be expensive - perhaps meaning that the ROI was not acceptable (at that time?).

With a more reliable engine and a far better economy, I would expect more effort in that area. IF India wants to be an engine power, they better have world class facilities. However, for that to happen confidence needs to be rather high (in engine design, etc).