Kaveri & Aero-Engine: News & Discussion

compved · Post by **compved** » 30 Jul 2009 04:39

Any update on the Kaveri engine folks ?, I would like this engine developed at any cost, I reckon this is almost as significant as developing the N Sub. What can be done so that the Indian government directs some of its funds/energies to accomplish this ?.

k prasad · Post by **k prasad** » 30 Jul 2009 15:56

compved wrote:Any update on the Kaveri engine folks ?, I would like this engine developed at any cost, I reckon this is almost as significant as developing the N Sub. What can be done so that the Indian government directs some of its funds/energies to accomplish this ?.

Patience good sir... what needs to be done, is being done!! All parties have woken up, and work is happening, although, just as Rahu sometimes clouds the sun from the earth, the logic of some moves is being clouded from us Jingos by the MoD babus and DRDO and IAF wallahs... we can only wait for the word.

Vivek K · Post by **Vivek K** » 30 Jul 2009 20:30

A Kaveri to the original specs, good MTBO would be a good step and help in the MCA. India should definitely develop the MCA.

RKumar · Post by **RKumar** » 30 Jul 2009 20:58

^^^^
+1

Willy · Post by **Willy** » 02 Aug 2009 13:09

Is the Kaveri like dead or are they going in for a JV for an entirely new engine?

karthik · Post by **karthik** » 02 Aug 2009 13:39

What surprise me is GTREs lack of ability to redesign.In the past 20yrs they are just working on one design, we should have had other simultaneous designs from existing current technology or copy cat designs to choose from, while the Single Crystal Blade Technology is given some space to breath and develop slowly.The single crystal blade technology is very new and even the advanced countries have not inducted it fully. We must have an back up design with current technology that we can use right away. Its amazing how GTRE is completely relying on an experimental new technology which should be under R&D for the next generation fighter rather than using existing technology to meet the short gap which is urgent.

Its already done a beautiful job with the Kaveri,they should pat themselves on the back for that but also do a redesign on the dimensions and metallurgy to get a slightly realistic design that's at least as big as the F-404 for now.

KrishG · Post by **KrishG** » 02 Aug 2009 13:46

Was Kaveri's bypass ratio supposed to be 0.16:1 or did GTRE end up with that figure?? Doesn't it make the specific fuel consumption of Kaveri higher than other engines of similar thrust-class like RD-33 and F404 ??

Willy · Post by **Willy** » 04 Aug 2009 23:23

THE KAVERI IS DEAD!!! LONG LIVE THE KAVERI!!!! I hope someone has the sense to start working on an engine for the MCA right now. If not 10-15 years from now we will be discussing why the MCA is failure because of its engine.

NRao · Post by **NRao** » 05 Aug 2009 00:27

What surprise me is GTREs lack of ability to redesign

Yeah, it happens when there is no need for a "redesign". When there is reluctance to build something where there is a dire need how can we expect "redesign"?

This is a nice article: crown jewels :: These crystals are the gems of turbine efficiency

The recent best seller by Tom Friedman, The World Is Flat, examines how companies are coping with the continuing evolution of globalization. The gas turbine manufacturer Rolls-Royce, for instance, outsources and offshores about 75 percent of its components to its global supply chain. But what of that remaining quarter?

Friedman quotes Sir John Rose, Roll-Royce's CEO, on the components the company still makes: "The 25 percent that we make are differentiating elements. These are the hot end of the engine, the turbines, the compressors and fans and the alloys, and the aerodynamics of how they are made. A turbine blade is grown from a single crystal in a vacuum furnace from a proprietary alloy, with a very complex cooling system. This very high-value-added manufacturing is one of our core competencies."

The article was written in Feb, 2006!!!!!

India, even today, is thrilled to get a small portion of that meaningless 75%. Tata will make doors for Boeing .......... True that it provide valuable employment.

vina · Post by **vina** » 23 Aug 2009 08:27

Since esteemed mullahs have multiple questions and seem to be bent on skewering GTRE and Kaveri, let me put my thoughts on some of the stuff that has been discussed.

Since I have been doing YumBeeYea giri for long years now and havent opened a book in engineering in ages, let me use some basic materials I found online. After all , all I remember is "Conclusions" . So need to go back to K-12 /high school and who better to help out than NASA ?

General Thrust Equation

This Index of Propulsion has everything in it in beginner's terms..

1) Bye Pass /Operating Cycle -

Let us refer to the basics of why a turbo fan is more efficient than a turbojet and why generally in subsonic regimes, higher the by pass , the more efficient the engine is.

Turbofan Thrust
[

There , fundamentally, we have

Total Thrust = Fan Thrust + Core thrust

Ah.. Elementary my Dear Watson, eh wot ?. The key for high efficiency and or in Inglees, more thrust for the same amount of fuel burnt or vice versa, for a given thrust less fuel burnt, you want to to make sure that bulk of the thrust comes from the fan and much less from the core.

so what is the fly in the ointment ?

Look at the equation for Fan thrust above. The fan exhaust quickly and rapidly falls to zero as the fan exhaust velocity falls to the free stream velocity !.

Now as the plane flies faster and faster, the fan exhaust velocity quickly starts approaching free stream velocity (the speed at which plane is flying) and beyond mach 1, the fan thrust probably contributes zilch/nada/shoonya/chipher /ek bada anda to the total thrust in a large turbofan!.

So what was drilled into my head long long ago as "conclusion" still holds.

At higher sustained mach numbers, low by pass is kosher!.. Because, the effective thrust at such regimes comes from the core and not the fan!

2) Bye Pass Ratio- Turbine Entry Temperature (aka, Yindoo Dhoti type excess air convection cooling , Vina TM)

Well, let us look at what exactly happens beyond the diagram /schematic we have from the link. Now let us go to say undergrad levels beyond K-12 levels.

Unlike in a car/bus/motorcycle/ship and other engine with more extensive cooling arrangements , jet engines DO NOT operate with stochiometric mixtures of air and fuel. If such an exact stochiometric mixture (probably 12:1 or 14:1 air/fuel ratio) was fed into the combustion chambers (ie all the core mass flow was mixed with fuel and burnt) and there was no unburnt air from the core flow to cool it by mixing, the turbine downstream would be melted into a blob of molten metal, whatever exotic ding-dong you put on it.

Bottomline,

No jet engine core in the world extracts 100% of energy that is theoretically possible , because there is no material today that can withstand such temperatures

Now comes Kaveri.. The max TET they have published is 1700K. That is because that is the temp we can achieve (usually around 150 to 200 K ABOVE melting point of the material via cooling arrangements, before it turns into a glowing blob of metal). While contemporary engines in the west have materials which have TET of around 1900K or so. So there you have it.

A similarly sized core in the west would put out FAR higher thrust/power for similar core airflow as Kaveri (because, a higher portion of the core airflow can be mixed with fuel and burnt), or for a given thrust/power, a western core would be MUCH smaller , requiring less core air flow ! (this flows onto point 3)

3) Efficiency /Summing it up --(aka back to bell bottoms and 1970)

Now since LCA has been slurping up a lot of Ambalapuzha Payasam from the Krishna Temple near Enqyoob's home town , it has put on nice haunches like Tamil film heroines.. So , IAF says,

We need 20% more thrust from same airflow and engine size!

How do you do it ? . You basically have to increase the overall efficiency of the engine!. What the IAF is basically keen on is the high take off thrust so that the high payasam fed LCA can take off with all the sweets and ample belly filled with fuel for range.

Now that leads us directly to point number

1). Increase by pass so that the take off thrust is increased!.
so Ok.. now I do that and take the air that would flow to the core and route it using the fan , which leads us to point number
2) Now since there is less air (and hence less excess air) in my dhoti, the turbine will melt for the same power output as earlier!

So what to do ? Run to vilayat (or if you can kick DMRL's bottom and the come up with the materials by magic) and get the materials that will run at such high temperatures ! That is the solution. However, it is not so simple as just putting the new materials and things will be fine. You basically have to redesign the core for the lower air flow and higher power output. Hmm so a brand new core is required!.

The IAF is now breathing on my musharraf and saying I want it now!. So what do you do. Go to Vilayat for the new core that will work. So that is what GTRE did with the Snecma Eco Core !

4) Going forward.

The way forward is like this. So whatever you do, you need to get the TET to contemporary levels. Once you do that , the thermodynamic efficiency (ie, conversion of heat to mechanical increases , coz you are sources is at a higher avg temperature and the efficiency of the core increases.

If you get that into the current Kaveri core, you basically have a core that is TOO BIG for the LCA's thrust levels. But the flip side is with a new LP system and higher overall mass flow , you have an engine that is well suited for a much higher thrust level .

So basically what the GTRE has done is not put the core for the Kaveri, aka Kabini, but actually made the core for Ganga, aka Gangotri

! Yeah, you need the high temp single crystal materials for that for sure to be efficient.

Overall efficiency --> Core thermodynamic efficiency & Conversion to thrust efficiency..

5) Flat rating, sooper cryuuze and Eqyoob's photo in bell bottoms.

Flat rating is to make sure that you don't have your musharraf uncovered under any circumstances. Say if you flat rate at ISA +15 or +20 / whatever, you atleast guarantee that much thrust under those conditions.

A DDM brouchirite reader would say F-4XX puts out 100000000000 lbs of thrust (limited by TET).. But that is at ISA!. It will derate at +15 or +20 etc, sometimes alarmingly.

Now because of Yindoo Dhoti Cooling (due to low bypass and excess core flow), the Kaveri's turbines still have some excess margin to go before it hits temp limits. So basically the turbine temp will be allowed to that limit at design limit.. Or in Inglees.

Flat rated XX thrust at ISA +20 = XXXXXXXXXXXXxxxxxx thrust at ISA

Sooper Cryuuze --> Refer point 1. We can have a Ganga sized engine with better materials which will can easily supercruise (it will have a higher bypass than 0.16, I grant it, but still much smaller than the SU30's 0.6) , which can easily put out the required dry power. The key to super cruise is high dry thrust and NOT total thrust in supersonic regimes ..and that brings us back to low bypass and a core that is thermodynamically efficient (ie erect when in high garmi)!.

Back to 70s --> Since we are going back to 70s kind of by pass numbers (albeit with new materials at higher TET and hence higher thermodynamic efficiencies), isn't it sort of going back in fashion to 70s and bell bottoms , albeit with new high tech flame proof aramid fiber blend fabric as trouser material instead of the polyester of the 70s? That is why I keep saying saars..

You may have Passion, but you need to watch out for Phashion!

And Finally

Dear Enqyoob, WHERE IS THE LINK OF YOU RUNNING AROUND IN THE MADRASSA IN THE 70s IN BELL BOTTOMS, WITH SIDE BURNS AND MOUSTACHE?

negi · Post by **negi** » 23 Aug 2009 09:17

^ Vina ji afaik flat rating is done for

1. To ensure constant exhaust gas temperature which helps preserve hot section .
2. To guarantee the that thrust figures on brochure are actually met.

The flat rating or maintaining constant exhaust gas temperature is tricky as again we are dependent on T.i.T as the former is directly propotional to latter.
Flat rating is done when a GT engine designed for delivering 'x' lbs of thrust is infact actually capable for delivering 'X' lbs (where X > x) which is not the case for Kaveri.I think it is imperative that all the jet engines are flat rated ?

tejas · Post by **tejas** » 23 Aug 2009 09:29

Vina garu, thanks for that excellent summary of the morass we are currently in with the kaveri. Looks like without single crystal blades we are up xxxx creek without a paddle.

John Snow · Post by **John Snow** » 23 Aug 2009 13:01

Vina Garu > So it it safe to conclude

"with out SCB we have Kaveri waiting to mate, with ED house bind'
If we do Bypass surgery no garami medication, is possible at this time . ( like if you use nitrates for chest pain Niagara is not allowed).

TIA

geeth · Post by **geeth** » 23 Aug 2009 15:46

>>>Now as the plane flies faster and faster, the fan exhaust velocity quickly starts approaching free stream velocity (the speed at which plane is flying) and beyond mach 1, the fan thrust probably contributes zilch/nada/shoonya/chipher /ek bada anda to the total thrust in a large turbofan!.

>>>Sooper Cryuuze --> Refer point 1. We can have a Ganga sized engine with better materials which will can easily supercruise (it will have a higher bypass than 0.16, I grant it, but still much smaller than the SU30's 0.6) , which can easily put out the required dry power. The key to super cruise is high dry thrust and NOT total thrust in supersonic regimes ..and that brings us back to low bypass and a core that is thermodynamically efficient (ie erect when in high garmi)!.

To me above two statements appear to be contradictory

Why SU 30 Engine needs a high bypass engine? and why not LCA?

enqyoob · Post by **enqyoob** » 23 Aug 2009 16:31

vinaji:

I think I responded to the above on the ellceeya dhaga b4 halal pingreji was panned theyar by GTRE-RAW and jarnails.
All NASA fundas about pie-bass are halal, BUT... the following is not halal, sorry:

At higher sustained mach numbers, low by pass is kosher!.. Because, the effective thrust at such regimes comes from the core and not the fan!

Think of an injin as operating inside the inlet/exhaust casing. For most injins (very few operational exceptions that I can think of - maybe SR71 would be close..) the injin ALWAYS operates in low subsonic/ mid subsonic flow.

The suberjonic inlet and the diffyoojer take care of reducing Mach number down from whatever, to about 0.4. With minimum losses in ishtagnashun brejjar. So ellcee ya may be subercruijing like magic djinn carpet at Mach 2.5 at 50,000 feet, but injin thinks it is at Mach 0.4 in downtown Yelahanka (I have not worked the madarssa numbers, just an example).

IOW, the injin face (compressor, fan) only sees Mach 0.4 or Mach 0.5, regardless of what the outside duniya is flying at. Likewise, what comes out of the turbine in dry thrust case, just goes to the con-virgin part of nojjel, only sees fairly low Mach number (OK -- actual Mach number inside final turbine stage may reach 1 in the narrowest dark yindoo kufr worship passages).

Digreshun: Also, the common belief that the exhaust velocity has to come out faster to fly faster, is not quite true. Consider that if you are flying at 600 m/s, then the hava is coming in at 600 m/s. If you do NOTHING to it and suffer no losses, it will bissfully go out at 600 m/s as well, at the same brejjar as the outside hawa. If you manage to add ANY work to it, it will go out faster than 600 m/s so you get thrust. Of course, to fly at that speed, with all the drag, you need to add a LOT of thrust, but this does not mean that the jet exhaust has to be faster. There can be just a lot of it (i.e., high pie-bass) moving at 603 m/s. In fact, the idea of "Brobuljib ephijjienjy" tries to tell you that the Most Efficient Magic Djinn Carbet Has Exhaust ispeed = Flight ispeed. Zerrow thrust, zerrow work, but VERY efficient. Like Guvrmand PSU, for instance.

The die-virgin part of the nojjel, TVC etc. should be considered to be something else.

So only things that matter to injin performance are:
1. Highest possible pressure b4 heat addition.
2. Highest possible temperature at end of heat addition.

Quite regardless of the Mach number of the outside duniya.

Here, big commercial injins like on saath-saath-saath / L'Airboos teen sau assi achieve, say, 52 atmospheres, and maybe 2050.374579K per Highly Classiphied Binori Madarssa Magic Djinn Carbet Manual, which is around 1780C. This is circa 3,236,000,000 Madarssa Far & High degrees. Or maybe much higher, I wouldn't know.

Eph-100-220 injin was at, say 27 atmospheres. Unspecified T-i-T but I would guess 2100K.
Eph-414 is also around 27 atmospheres, but they have reduced the weight very much by going to counter-rotating compressor & turbine and cheating on number of stages required, and on parts count. So they have lot of thrust to spare.
Eph-135 apparently has gone way up - 35 atmospheres?? Very high for a Fauji Injin. So now they have hajaar more work available, and they can use it either to run the Lift Fan (which is equivalent to going PieBass of hajaar) or they can put much more oomph into the fan (maybe they have some variable angle fans to do this, I wouldn't know). Hence supercruise.

Compare to Kaveri - Peak pressure is I think around 20 or 22? BIG difference. And I think the peak temperature/ "flat-rated" or otherwise, is probably too low to mention here.

The Kaveri achieves that pressure, with the SAME number of stages of compressor as the F-414 etc. So now you may begin to see where the technology gap is. The low pie-bass is NOT a design choice made for "supercruise" or "Indian condishuns" or any such PR garbage. It is because the compressor technology is backward. This is not "materials" this is not "sanctions". It is poor R&D and poor engineering. No way to escape this conclusion, sorry. Waaay back at the beginning of the discussion I mentioned some indicators that this is so, but if I repeat those now, it will be like pointing fingers.

For the second issue: Peak Temperature.

Now it also so happens, as you say, that stoichiometric flame temperature at such high pressures for even saada kerosene, is something well above 2200K. Maybe for halal jet fuel, it is around 2500K, or even more. So djinns are employed to ensure that no solid surface encounters such temperatures. This is very easy, because the exhaust coming from the flame is immediately diluted with unburnt air coming through various holes in the combustor walls, as the Mujahaheddin pour into Doda through holes in the Yellow Sea fence.

BUT... as far as possible, the ACTUAL HEAT RELEASE occurs at stoichiometric or slightly leaner conditions, AFAIK. No sense in not doing this - the reaction rates are highest here, and so "complete combustion" is best achieved here. To do this, people do all sorts of Fakkir contortions.

Note that these days the combustor is neither "annular" as in (just a gap around the shaft) nor "can" (set of lotas arranged around the shaft, each with its own tandoor inside, and a tunnel pipe connecting them to ensure that if one tandoor lights up, all tandoors light up).

These days the combustor looks like the large intestine from a goat - arranged at a sharp slant angle. Djinns have figured out how to make the hava go in contorted passages without much loss in "ishtagnashun brejjar" by very careful use of See-Eff-Dee and much, much soosai testing. The slant further increases the "residence time" inside the combustor, ensuring that no fuel escapes without being converted to halal relijjun and sent to Houristan.

Even more fakir-like, see menshun of "reverse flow combustor" (see Great Satanic injins like Eph ek sau painthees). This means, I guess, that when unburnt hava is pushed into combustor by comprejjar as the ISI pushes the newly-minted Binori graduates through the holes in the Yellow Sea, they see veteran converted hawa coming AT THEM with their pajamas on phyrr and INSAS up their musharrafs and panic in their eyes. Big mixing takes place, as between veteran Mujaheddin and peachy-cheeked carnation-eared recruits.

Point of all this is a very phundamental phakt: Best heat addition occurs when Mach number is zerrow. In phakt, all injins work best when isthanding ishtill (so GTRE Injun-Injin disblayed in the glass case should be a duniya-beater in this respect).

Somewhere in the ancient dins b4 u saw the light and escaped to Mgmt, they may have menshunned something called "Ray Lay's Line" which says that adding heat to fast-flowing fluid is as wasteful as giving AK-47s to fast-running Paki Faujis returning from battlefield. Most of the ishtagnashun brejjar is lost.

And this in turn, is why the musharraf-tandoor (aka AB) is very inefficient. So - bottom like is, if you can make your injin light enough and still get enough thrust without mushtandoor, then yuwar injin is hajaaaar more halal.

If you DON'T know how to make it efficient, and your core pressure can only reach 20 atmospheres and your T-i-T is stuck around 1500C, then you cannot do this.

Again, this boils down to poor R&D. It is NOT limited by materials at this point, in my madarssa-educated guess. There are plenty of flames operating every din in India at 2500K etc. Acetylene torches, for instance. Why don't they melt? Likewise, you can have a jet engine combustor where the flame itself occurs at stoichiometric temperature, and then you bring the average temperature down to the material limits and keep it well mixed and uniform, through CAREFUL, PERSISTENT design and iteration and measurements and testing and back to design etc. Every saal you manage to get it more efficient, more uniform and closer to material limits. In 40 years it should have come waaaay higher than today's level.

Are desi DOOs and PIGS incapable of doing the See Eff Dee and the See Ay Dee to design burners that work better, hain? Are desi Ambassador car shops not capable of building and testing these, hain? Any cycle shop mechanic can check what happens when, say, an acetylene torch is brought close to the combustor walls or First Stage Turbine Nozzle of the Kabini Core and check at what temperature it goes soft. Don't they have thermocouples and voltmeters in India, hain? In fact I think they have infrared cameras to do the job far better. So what's the excuse for this? (yes, I do have a good sense of what is actually happening...)

*******************
Now for the bigger catch in this setup:

The pressure ratio and the peak temperature are closely related, for several reasons.

1. High pressure ratio means better thermal efficiency in converting from heat to work. Per Mullah Imran of Binori talking about the teachings of Mullah Gadda Bray-ton the great Cyclist:

Eye-Dee Al EtaThermal-e-Brayton = 1- (1/(PeeAr))^(1/3.5) where PeeAr is Brejjar Rashio.

So if you have 20, Al EtaThermal-e-Brayton is 57.5%.

If you have 35, Al EtaThermal is 63.7%

IOW, with Kaveri, it is like throwing away 7% of the fuel out the back end compared to the F-135, right there.

2. Stoichiometric Flame Temperature depends on pressure, and generally increases with pressure. So a 35 atmosphere flow can reach a much higher temperature and more complete combustion than a 20 atmosphere flow. So the low T-i-T and low conversion efficiency from fuel to heat, may be PARTIALLY due to the low pressure ratio. IOW, this is like some of the fuel being poured to the side as it goes into the combustion chamber, BESIDES the 7% being poured out the back.

From the above you see why something like the eph-eksau-paintheese can "supercruise" with a substantial drag load, while the Kaveri is not going to do anything of the sort.

This should answer the pooch above, why Su-30MKI can supercruise with so much higher piebass ratio injins.

As I menshunned on the other haraam dhaga, iph theyar eej a new Magic Carbet Bin Concorde, it will have injuns oph PieBass ratio around 3 or 5 if not higher.

3. OTOH, improving the compressor technology without improvements in the combustor and turbine is not going to be adequate. Suppose the compressor by djinn magic, can achieve pressure ratio of 50. The work required is very large. The gas also gets hot due to compression, and reaches some high temperature. Now not much fuel can be added b4 the temperature reaches the material limit, so not much work can be extracted, so this whole scheme won't work.

So both the pressure ratio and T-i-T have to increase, in step with each other.

*********************
NOW we come to the design decisions in the Kaveri.

So you don't have good compressor design, and you don't have good combustor design. How do you meet the THRUST specifications, given a duct diameter to stick the injun in?
You fill the available engine duct area with CORE. (IOW, Lo-lo- piebass). Very inefficient. Low Thrust-to-Weight (T/W) ratio. High exhaust velocity, so low Propulsive Efficiency. Poor combustion so plenty of smoke. High exhaust temperature so easy for missiles to detect. Noise proportional to Ue^6, so it can be heard all over Bengalooru, Kerala.

Consider that if this fails, then you can always fill the whole engine duct with a rocket engine, and get hajaaaar more thrust. For very short flights.
**************************
Consolation:
But I can, in all fairness, see why present-day managers, under pressure to meet LCA specs, would still bravely march ahead with this low bypass design and argue that it is futuristic. They may reason that one day by sheer magic, the Kabini Core will begin producing a pressure ratio of 35 and a T.i.T of 2200K, and the turbine blades won't "throw". Voila! Suddenly you have all kinds of extra work available. A small increase of fan diameter (see the difference between F404 and Kaveri) and you get a much larger Bypass Ratio. (Per Mullah Al Geo-Mistry, annular duct area goes up fast with rise in outer radius). Will fit in same passage as Ell Cee Yay. Supercruise!! Bismillah!

Question is, where is this djinn magic going to come from, to take the Pressure Ratio from 20 to 30 or 35, T-i-T to 2100K, and T/W from 6 to 10? This will take very intense R&D. You don't go from Stage Pressure Ratio of 1.3 to 1.6 without some serious work (actually this means that some of the downstream stages may operate at up to a pressure ratio of 2, because you try to keep the front stages, where there can be large fluctuations due to angle of attack, rain ingestion etc., quite low to avoid stall and surge).

It will take willingness to put hajaar DOOs and PIGS to really WORK, developing in-house codes and validating them against basic, applied and full-scale experiments. It will take a couple of dedicated full-scale test chambers where the pressure can be taken way down. Dedicated test rigs where you can blow up engine cores at 30,000 rpm and not suffer much delay. Dedicated engine resonance test rigs where counter-rotating shafts and stages can be developed.

A lot of materials work, a lot of combustion/ flame holding work. Lots of compressor and turbine aerodynamics if you are going to get stage pressure up to the needed level.

These things cannot happen in the 50-year chalta hai culture of GeeTeeAREeee and EcHAy-elL. They need War-Phooting Urrjant Briority and an organization run by an SOB with free hands to tweak ears and free feet to kick musharrafs. Bring in every injineering madarssa and every pissiks and chemistry MSc department to develop the solutions. Give them projects with Deliverables Deadlines and the surety of funding cut-off if deadlines are not respected. Make them give presentations justifying THEIR existence, instead of just pretending to do work. Weekly reports. Red Team Reviews. Plus, of course, long-term projects to the best researchers to do their stuff in peace and quiet, once it is demonstrated that they have clear long-term aims to make major breakthroughs. This is why the guy/gal who runs this has to be SOB/DOB AND very knowledgeable and forward-looking, and has to have very strong top-level support.

Hence my

The way things are going, I predict that GTRE PeeAaRR Department will come out with a new announcement:

Instead of reverse flow combustors, we are having reberj-phlow combrejjar onlee!

geeth · Post by **geeth** » 23 Aug 2009 19:32

>>>The suberjonic inlet and the diffyoojer take care of reducing Mach number down from whatever, to about 0.4. With minimum losses in ishtagnashun brejjar. So ellcee ya may be subercruijing like magic djinn carpet at Mach 2.5 at 50,000 feet, but injin thinks it is at Mach 0.4 at in downtown Yelahanka (I have not worked the madarssa numbers, just an example).

Not only that - most of the time the plane will be flying subsonic. For supersonic flight, it has to fire its afterburners (since no supercruise).

No time now. have to go...talk later.

Raj Malhotra · Post by **Raj Malhotra** » 23 Aug 2009 20:04

Why should GTRE work hard to develop engine tech of 70s when India is importing tank engines of 60s tech in ka-873 for Arjun, afterall everybody has equal right to be incompetent?

bala · Post by **bala** » 23 Aug 2009 21:51

Narayanan wrote:Think of an injin as operating inside the inlet/exhaust casing. For most injins (very few operational exceptions that I can think of - maybe SR71 would be close..) the injin ALWAYS operates in low subsonic/ mid subsonic flow.

The suberjonic inlet and the diffyoojer take care of reducing Mach number down from whatever, to about 0.4. With minimum losses in ishtagnashun brejjar. So ellcee ya may be subercruijing like magic djinn carpet at Mach 2.5 at 50,000 feet, but injin thinks it is at Mach 0.4 at in downtown Yelahanka (I have not worked the madarssa numbers, just an example).

IOW, the injin face (compressor, fan) only sees Mach 0.4 or Mach 0.5, regardless of what the outside duniya is flying by at. Likewise, what comes out of the turbine in dry thrust case, just goes to the con-virgin part of nojjel, only sees fairly low Mach number (OK -- actual Mach number inside final turbine stage may reach 1 in the narrowest dark yindoo kufr worship passages).

Shri Narayanan that is why you are Grand Mullah.

Absolutely right. Supersonic outside but subsonic within engine. Basic funda question that every aspiring aero jet engine Engineer needs to know.

Without going through several iterations of working jet engine models, GTRE is flailing around talking grand theory when in practice they are yet to demonstrate a decent working jet engine.

Best way to energize the program is to have two programs running in parallel. the fear of the other guy beating you motivates you like no other incentive.

vina · Post by **vina** » 23 Aug 2009 22:50

At higher sustained mach numbers, low by pass is kosher!.. Because, the effective thrust at such regimes comes from the core and not the fan!

Sorry Mullah. That answer is right. Very right and I will tell you why. As usual, I will give you a YumBeeYea answer (after all I remember only "conclusions") and then try to go into details engg wise.

First the YumBeeYea answer
Now another "conclusion" dinned into my head from long long long ago..

At high Mach numbers, Ram jets start getting more efficient than turbo jets . The theoretical Ram jet always keeps increasing speed and will reach a goooooooogooooooool infinite velocity unless the fuel flow is throttled back.. In Real life, materials limit the speed to reasonable numbers

So what is the by pass of a Ram Jet ?. Easy answer no ? .

Zilch, Nada, Zero, Chipher, Shoonya, Ek Bada Anda!

. Why is that ?. Because, by definition, Ram Jet DOES NOT have a compressor/core, so the entire engine flow goes through the core!.

So Mullah's Sermon

You fill the available engine duct area with CORE. (IOW, Lo-lo- piebass). Very inefficient. Low Thrust-to-Weight (T/W) ratio. High exhaust velocity, so low Propulsive Efficiency

Is absolutely right. But unfortunately is only partly right . Why is that ?. Mullah is absolutely right in SUBSONIC flight. However in sustained supersonic flight, it is counter intuitively different.

Again a YumBeeYea answer before Yingeering answer.

SR-71 had a variable cycle engine. As mach numbers increased , it switched airflow completely out of the core /compressors and bypassed it and basically turned into a Ram Jet! Combustion took place just like Mullah explained, basically do ZERO bypass, UNLESS it was more efficient , especially when they had ALL The turbomachinery in place (in fact used it to get to supersonic) right there. Why switch cycles to ram jet and not continue with the turbofan cycle they used to take off and get to that speed?

Mullah Vina's observation

zero by pass is the limiting point.. Like you want 100% bypass (basically a prop /dis as per momentum theory) at zero speed, you want, 0% bypass at high mach. At between Mach 1.3 and Mach2 which new fangled Sooper Cruyze works, you will need an inbetween low bypass, at around 0.3 or 0.4 max)

Now YinGineering answer.

The NASA General Thrust equation diagram DID NOT talk about supersonic/ subsonic flow inside the engine etc for a GOOD reason. IT is an IDEAL equation. You can replace the engine picture with a black box and the equation will still hold!. And why is that.. Go back to fundamentals!.

The Thrust EQUATION IS JUST NEWTON'S 2nd Law (change in momentum), in a different form!

Now what happens internally is entirely immaterial and is a black box. As a Fyzzicist would put it , all the forces and processes in the black box are "internal forces" and dont change the overall outcome , as long as there are no losses and they are ideal.

The problem is simple.

What is ideal for subsonic is NOT ideal for sustained supersonic!

In subsonic, all that you said is perfectly right. I wrote on that too in my earlier posts. You will NEED as high a by pass as possible and have as low a core flow as possible. That is MOST efficient. And that is why you have HIGH Bypass turbofans.

Now however, that will not work in SUPERSONIC regimes for two simple and VERY important reasons.

1) The frontal cross section area due to disc and drag increases with a big fan. For eg, in the GE-90 in the highest thrust versions, the fan diameter is HIGHER than the cross section of fuselage of early B 737s!

2) Very important reason I told earlier. The FAN THRUST FALLS OFF VERY RAPIDLY.

Now how does no 2 come about ?.

Let us go back to the thrust equation and specifically fan thrust .

Fan thrust = mdotf ( vf - vo).

The problem is this and that is exactly what you posted !.

In a real world as of today, the air flow has to be declerated to subsonic, because as of today we dont have supersonic combustion!

So this brings back to the point. Now How much ever work you do with the fan .. beyond a point in supersonic regmie, vf will be at best equal to vo. how much ever work you start adding . (the flow will have to accelerate to vo at the black box boundary)!. The fan thrust will be EFFECTIVELY ZERO.

Consider that if you are flying at 600 m/s, then the hava is coming in at 600 m/s. If you do NOTHING to it and suffer no losses, it will bissfully go out at 600 m/s as well, at the same brejjar as the outside hawa. If you manage to add ANY work to it, it will go out faster than 600 m/s so you get thrust

Precisely. This is true in subsonic. However in supersonic flow, no fan will be able to add work on the air flow especially when you first have to decelerate it and the resulting flow will end up being faster than the stream flow, because of the losses and shocks you will suffer.

And it is exactly for that reason, there is NO PROPELLER plane that has able to go supersonic and it required the advent of jet engines to be able to delivery enough thrust to go supersonic ( the propellers cannot convert the engine power into thrust , even if the engine put out thrust!)

Remember the old question /quiz?

A rocket can fly faster than it's exhaust. Can a jet fly faster than it's exhaust?

About combustion and efficiency .

Another conclusion that got dinned into my head is this.

Piston Engines are more efficient than gas turbines and
something called pressure law ie. P/T = const (under const volume)

And why is piston engine more efficient ?. Because the Average Pressure and hence temperature (doesnt matter if you do the analysis using pressure or temp, they are both analogous and equally right. it is the same as using T-S diagram or P-V diagrams.. equivalent) are HIGHER than in a Gas turbine. How is that ?

In Pinglish, mullah says

This is very easy, because the exhaust coming from the flame is immediately diluted with unburnt air coming through various holes in the combustor walls, as the Mujahaheddin pour into Doda through holes in the Yellow Sea fence

In Ingless, I says.

there was no unburnt air from the core flow to cool it by mixing, the turbine downstream would be melted into a blob of molten metal, whatever exotic ding-dong you put on it.

Net result. The average Temperature in a Gas Turbine before it is can be expanded to extract work is less than what you get in your 100cc Hero Honda motorcycle ! (gas is expanded by piston moving in mobike, and in GT by reaction turbine spinning!) That is why it is less efficient.

So if you have 20, Al EtaThermal-e-Brayton is 57.5%.

If you have 35, Al EtaThermal is 63.7%

Mullah is absolutely right here. Yes, the Kaveri core as it is is Thermodynamically not efficient. However, that is not because of anything , but because of material limitations!.

Remember, if you develop the kind of peak pressures (P and T are two faces of the coin remember), the temperature will exceed the max of the turbine. Now, you cant increase P without increasing T!. So there we are back to materials again.

So a 35 atmosphere flow can reach a much higher temperature and more complete combustion than a 20 atmosphere flow

Well, no one in their right minds will go near exact stochiometric ratios in a gas turbine. In fact, historically, they tended to pump in EXCESS fuel (check out the mig 29's exhaust for the black sooty smoke) for a less than ideal stochiometric ratio to keep temperatures down ! Atleast the brits were more honest about it and used water injection to get temperatures down.

However, you are right comubstion chambers will need near stochiometric ratios for efficient combustion and ability to sustain flame front . Check out lean burn auto engines.. Even in stratfied charge engines, the piston heads are shaped so that the mixture is richer near the spark plug for the combustion to happen and the flame to propogate. But the point is, unlike in gas turbines, the no mixing with excess air before it is expanded and work is extracted.

Question is, where is this djinn magic going to come from, to take the Pressure Ratio from 20 to 30 or 35, T-i-T to 2100K, and T/W from 6 to 10? This will take very intense R&D
IOW, with Kaveri, it is like throwing away 7% of the fuel out the back end compared to the F-135, right there

Well, the easy solution is to go to Vilayat, like I said, now that we are Munna and also near Al-Lie. Doing the materials manufacture and R&D can come later.

Willy · Post by **Willy** » 23 Aug 2009 23:36

Dudes stop discussing the kaveri. Its like chinese torture. This tread should be locked till the kaveri is resurected as a JV with some foreign partner as an engine capable of supercurise and thrust vectoring for the MCA. Till then let it rest in peace.

sivabala · Post by **sivabala** » 23 Aug 2009 23:41

Dear N^3 et al. jis,
All your discussions are really good and teasing the brains to think. But, I am not sure if a neta or babu with an slightest of inclination to improve the GTRE and go through your views he will have to work eons to decipher your enigmatic suggestions. So humble mujahid's request is to write in English rather than Pinglish, unless you expect visiting syeds and Ayeshas to implement your suggestions in Porki-TRE.
Thx.

Jagan · Post by **Jagan** » 23 Aug 2009 23:59

simple english please.

arunsrinivasan · Post by **arunsrinivasan** » 24 Aug 2009 00:56

^^^
third that. for the sake of us lesser mortals

BajKhedawal · Post by **BajKhedawal** » 24 Aug 2009 01:57

Well I disagree with all of the immediate three posts above

In my very humble opinion (I hate acronyms, so there…)

Actually this aam abdul from LMU understood more about the intricacies of the technology involved from Shri Narayans post rather than from the various techno jargon loaded, I know more than you; no! I know more than you; no, no, no I know more than you threads/posts elsewhere + everywhere.

Shri Narayan understands that for a normal regular block to be able to distill phacts from above you have to adulterate it with some phun.

enqyoob · Post by **enqyoob** » 24 Aug 2009 02:51

J-Gun, there is a reason to conduct certain discussions in languages where certain search terms don't hit. Enough said.
(Besides, I c that most REAL discussions even between the jarnails is now conducted in halal Pingreji)

People once sneered at html too, and said: "Talk REAL Assembly Language or COBOL like high-society Computer Scientists do!"

As for the reading-challenged and thought-challenged BRF experts or desi High Babus with the one-sentence pearls of wisdom, it is not my intention to cure the ills of either, thank you, and what such log kahenge is of very small consequence to me - these are the same people who are "responsible" - a loose use of the term, for the dismal state of affairs in Indian gas turbine R&D. If you are not interested in knowing why the Kaveri project is in its present shape, you can always go do something immensely useful and intellectually impressive - like go discuss Partition or Jaswant Singh's Memoirs.

I'll just suggest gently that if you can't understand things explained at the madarssa level that we mullahs use, there is not much hope. Stick to PR and HR as career streams and stick to repeating Buzz Phrases like "flat-rated thrust" and "variable guide vanes" and "digital engine control" and "supersonic cruise". There's tons of $$ and Power there.

vinaji:

I am aware of strange djinn magic occurring at high suberjonic Mach numbers, but v r not in any danger of getting anywhere near those Mach numbers. The counter-argument to what the textbooks drilled in as Aydie Al Ramjetullah Worship is that Al Ramjet can be visualized as an engine with closer to Infinite Bypass than zero bypass. Consider:
a) It is not true that all the flow gets burned - far from it. Only the inner flow is really going to get burned unless you waste huge amounts of fuel dumped out the back. So you can look at it as a case where you pay to generate the compression by doing something (think of it this way, the fuel pump needs power), and add most of the heat after compressing.

b) Consider that the conical shock used to compress such flows, originates near the axis, so it is very much like a super-fast shock-in-rotor fan blade, doing work on the flow to compress it. The "Ferri thermal-compression engine" SCRAMJET is an example where this concept is really pushed. A little bit of heat is added near the front, causing density to go down and flow to turn, causing compression waves to go out into the flow, just like fan blades compressing the outer flow.
c) Beyond that, the supersonic ramjet (except the scramjet) ALSO has subsonic flow inside its combustion region, and all the way to the throat of the CD nozzle, and all the other things apply to it.
d) It cannot be anywhere close to "ideal" (exit Mach # = flight Mach number, exit ishtagnashun brejjar = flight ishtagnashun brejjar) unless the compression is very very efficient (through a large number of small shocks rather than 2 big ones) and the heat addition occurs after the Mach number is brought close to zero.

SR-71 was an example where the core was small, and the fuel was exotic (very high temperatures and very fast burning).

So it is still true that todin and kal, turbofans of increasingly higher piebass will be used. I know, that this is not what v were taught in the madarssa, but the reasons have changed with technology.

Now you bring up the other textbook point - about frontal area. True, true, this is why piepass of baarah or pandrah cannot be used for Fauji injins. In old days, the turbine engine had a big heavy wheel (which did absolutely no good and blocked flow) and small blades at the periphery, stuck in with "turbine tree" keyways. RPM had to be kept down, u c. Stages were designed with slide rules and Mean Radius Velocity Diagrams with Small Perturbations sufficient to analyze changes from the root to the tip, and with Ideal Vortex Machines and "r*Utheta = Constant" etc., and the tip losses were just considered to be "Vidhi" and left like that.

Todin, See Eff Dee allows dealing with blades that have wide and long and highly twisted blades, and very much smaller disc radius. The RPM can be accordingly very high, and so the stage pressure ratios should go well into the regime of nonlinear hava dynamics, with shocks interacting with other shocks, and all helping to keep stage pressure ratio high.

Which brings me very close to telling you y desi gas turbine design is so backward. No one is going to give away the tools to design those kinds of things, u c... not at any $$ value, since it would be equivalent to giving away one's chappati roller and tandoor. This is where the habit of rushing out to buy this and that Commercial Code, is doing to desi brains what opium did to the Chinese. I keep getting shocked (no pun intended) 2 c CVs of desi brats claiming 2 b experts on FLUENT, OVERFLOW, GIBBERISH, and all those other buzzword garbage codes, having used them at the fine labs of desi innovation. No wonder nothing works. No one says: " I worked on the huge Jatayu Parallel CFD code for Advanced Gas Turbine Boltzmann Equation Solutions".

Bottom line, take it from me - HIGH BYPASS is the way of the future, and does indeed work with very small engine frontal diameters. Mastering this is also the key to developing cruise missiles and UAVs, BTW.

So the textbooks need revision badly in this area, but there is no way to set good tough homework problems with the velocity diagrams for such machines, since it needs See Eff Dee Moving Grids to explain and see what is happening inside. Hence the prevalence of the ancient textbook descriptions.

For futuristic space launchers, a turbojet core is still considered, but think what would happen if, say, one could wave a djinn light wand around the duct at the speed of light, instantly causing compression waves, instead of spinning heavy mechanical blades. Fuel would still be mixed only with the inner 5% of the flow, and work may be extracted from that to create the djinn light wand. IOW, SCRAMJET is also going to be a high-bypass turbofan in the Next Gen SUPARCO Flying Swine.
********
Anyway, this is all digression.

However in supersonic flow, no fan will be able to add work on the air flow especially when you first have to decelerate it and the resulting flow will end up being faster than the stream flow, because of the losses and shocks you will suffer.

Not halal either. This is another aspect where the old textbooks and lecture notes got it wrong.

The "transonic core" (Kaveri claims to have that, or FutureKaveri will have that) implies that the rotor blades experience local supersonic flow, and always carry a shock. "Shock -in-Rotor" is the buzz-phrase there. The argument is that you can get a pressure jump of a factor of 2, easy, using a shock wave and supersonic airfoils. There will be a loss of ishtagnashun brejjar across the shocks, but the advantage of having a rotor stage reliably multiplying the pressure by 2 rather than by 1.3 (as in the case of Kaveri) makes it worth it. This is probably how the number of compressor stages has been brought down, with large gains in T/W.

Old injins, remember, used to have "5-ishtage low prejjar combrejjar and 10-ishtage high brejjar combrejjar" implying a massive number of blades, all waiting to fail at the most inconvenient moment. In contrast, today they just have some 6 stages of compressor, to reach pressure ratio of 30 or 35!

On a related note, there WAS something called a "supersonic throughflow compressor" in the glory dins of the Star War 1980s, where the axial flow itself never goes below Mach 1. This is of course intended for SCRAMJET type injins for space launchers, and wherever this research was done, I was not allowed to go anywhere near it. I have no idea if it panned out or not, and have never looked for papers on it.

***********************************
As for piston injin vs. jet engine, true, I suppose the piston injin does better because all the heat is added at constant volume (i.e., extremely fast while the piston is still essentially at the top of the cylinder), so entropy rise due to heat addition is minimal (I nearly flunked Thermodynamics in the Eye Eye Tea and got through merely because I memorized some buzz phrases) and then all the work of expansion is extracted directly as mechanical work, instead of just a percentage as in a turbine. However, pistons weigh a lot. I suppose the Kaveri-57 PR-machine will use Pulsed Detonations instead of pistons and thus claim to approach the efficiency of a piston engine? The Ell See Ay will sound really cool if the frequency is adjusted to that of a Harley-Davidson, hain?

Raman · Post by **Raman** » 24 Aug 2009 03:36

Since the ayatollahs of Chet Endjin Al Turbiny are issuing hadiths, I humbly offer my pooch. (I apologize, I am DOO onlee and not hawa yendjinneer

, but I do understand some madrassa math).

In page 381 of "Aircraft Design: A Conceptual Approach", grand mullah Dan Raymer gave this hadith:

The inlet system uses a system of shocks to slow the air to a subsonic speed. This creates substantial drag. However, the subsonic expansion inside the inlet duct contributes a positive force that more than makes up for the external inlet system drag. In fact, the subsonic expansion inside the inlet duct is the largest single contributor of thrust!...

This kaffir understands only the unbolded part. Could one of the grand mullahs please explain why/how the phenomenon referred to in the bolded section occurs?

Thanks.

enqyoob · Post by **enqyoob** » 24 Aug 2009 04:26

Diyar Rahmanullah:

The bolded part is both halal and haraam, just as Mian Musharraf has been suspected to be both jarnail and bangle-wearing.

If inlets could generate thrust, the Ell Cee Ya only needs a couple of lampshades turned endwise, hung on each wing, to take off and supercruise. Unfortunately, ATM has decreed that Thrust can be brodujed ONLY pie bayment oph Brobar baksheesh, viz., heat addition and conversion to work, addishun of kinetic energy etc.

However, the mujahid hu designs the components has to figure out precisely where the various forces are felt. IOW, where eej it that theyar eej low brejjar on one side and high brejjar on other side, so that the component wall should be built strong as the darwajas oph Attock brijon.

So he figures out that the forces are felt on the inside wall of the inlet, because the hava downstream eej at higher brejjar than the hava in phront. Hence he knows that eeph he eej not carephool, the inlet will blast off forwards, ending the flight.

Hobe this eej halal eggsblanashun.

Rocket injun designers also say that all the thrust eej felt on the upper wall of the combustion chamber. Their coujins hu design the nozzle claim that all the thrust is felt at the throat where there is a thrust bearing.

Atri · Post by **Atri** » 24 Aug 2009 05:37

Narayanan Swami out of his maya is capable enough of single-handedly converting Pingrezi into Gyaan-Bhaasha just like Sanskrit once was and Angrezi is today. Pingrezi will be the naalej zabaan in coming dins. AoA.

Afreen posts Mullah Enqyoobi. Learnt a lot.. Shokran...

vina · Post by **vina** » 24 Aug 2009 10:20

So it is still true that todin and kal, turbofans of increasingly higher piebass will be used. I know, that this is not what v were taught in the madarssa, but the reasons have changed with technology.

Now you bring up the other textbook point - about frontal area. True, true, this is why piepass of baarah or pandrah cannot be used for Fauji injins. In old days, the turbine engine had a big heavy wheel (which did absolutely no good and blocked flow) and small blades at the periphery, stuck in with "turbine tree" keyways. RPM had to be kept down, u c. Stages were designed with slide rules and Mean Radius Velocity Diagrams with Small Perturbations sufficient to analyze changes from the root to the tip, and with Ideal Vortex Machines and "r*Utheta = Constant" etc., and the tip losses were just considered to be "Vidhi" and left like that.

Todin, See Eff Dee allows dealing with blades that have wide and long and highly twisted blades, and very much smaller disc radius. The RPM can be accordingly very high, and so the stage pressure ratios should go well into the regime of nonlinear hava dynamics, with shocks interacting with other shocks, and all helping to keep stage pressure ratio high.

Oh, I see what you mean. Let me see if I really understood you correctly.

In Ingless, what this means is this :

Now the components have gotten much better.. much much better really from the bell bottom days. So what that means is that while earlier, to get the required performance, in the Mach 1.3 to Mach 2 range, you unfortunately needed to throw more of the haraam (low performance and inefficient mix) from high mach number cyecles, while unfortunately having to do with only minimal amount of halaal (hieg efficiency subsonic part of the mix).

But how things have changed. Because of all the improvements at the component levels (not surprising really, because of the massive research that went into materials and the subsonic and achiveable/practical supersonic regimes, rather than more exotic very high machs) , now the conventional engines have imbrooved to such a point that you can have a massive majority of hallal stuff in the mix and very little of haraam. So effectively you are saying that the point at which you will have to consider going into more "turbojet" cycles and at higher mach "ramjet" cycles has shifted away to much higher speeds than back in the bell bottom days!.

Very interesting and eyeopening. The difference between a salt miner and a 50,000 ft "observer" surely.

But surely this part has to be very easy no ?

No one is going to give away the tools to design those kinds of things, u c... not at any $$ value, since it would be equivalent to giving away one's chappati roller and tandoor. This is where the habit of rushing out to buy this and that Commercial Code, is doing to desi brains what opium did to the Chinese. I keep getting shocked (no pun intended) 2 c CVs of desi brats claiming 2 b experts on FLUENT, OVERFLOW, GIBBERISH, and all those other buzzword garbage codes, having used them at the fine labs of desi innovation. No wonder nothing works. No one says: " I worked on the huge Jatayu Parallel CFD code for Advanced Gas Turbine Boltzmann Equation Solutions".

With all those DOOs and PIGS around, it is very easy to get this done in a span of 3 years or so. Tell the PIGS in the top 5 Madrassa branches that there are "motivational" toffees around (ie No reccos, references to fly to videsh if you dont do good).. You can parcel it out to each madrassa by area (one for compressor, one for combustion etc.. etc).. PIGs will love it and Oink with pleasure. After all, PIGS need to do project in 8th sem and most of 7th sem and are usually on a haze of intoxicated smoke (either from tobacco or from stuff growing in Idukki or both) . So in 3 batches of PIGs , with decent IT/Vity project management , you can have top of the line stuff and can catch up with anything out there today in terms of analysis and design tools!.

You will have all the CFD codes for flow right from modeling the Euler flow with full inviscid stuff and no linear approximations and all the statistical thermodynamic stuff for combustion, high temp gas dynamics etc and also the CFD and FEA for mechanical design .. Very halaal only.

Strange if GTRE and other orgs have such program. I remember 80s PIGS writing combustion /grain burn pattern modeling programs for ISRO for Rs 150 or so a pop!. PIGs love such carrots / sweeteners.

Sanku · Post by **Sanku** » 24 Aug 2009 13:53

Since the Pinglish speakers moved here after the call to order in LCA thread cross posting ---

narayanan wrote: And Sankuji bemoans the non-existence of Engine Test Cells, even as he wails about the sheer mental strain of reading Pingreji - though he has nothing to contribute to the discussion except a grand declaration of the wonderful work ethic of GTRE.

Sometimes just reading is contribution enough right.

I have no personal/vested interest in GTRE (and because they graciously fed me chai biskoot on some occasions as a part of a guided tour to a gawkers group does not mean that I am under the debt of their "namak")

What I said was -- no doubt a lot of what you say is correct -- however the "blame" does not stop at GTRE (or start there) -- it is there in HAL etc etc..

In fact any thing that happens in ADA is nearly a miracle the program has enough structural problems (not the aircraft -- the program) including the issues you have listed here, motivation etc etc...

In fact the question is not why GTRE failed, the question is how others succeed despite the problems -- and my answer is simple -- every program that has succeeded to any extent in India owes its origin to a single dynamic leader who then seeds a core of other leaders in the organization who keep things going despite all the problems and create success when by all possibilities they should have actually failed.

In my understanding GTRE did not have those leaders (or they left early) -- now the role of putting right leaders on top is not of GTRE.

The failure of Kaveri is to put a passionate leader on top by its parent organization and that should have been also demanded by its peers at ADA etc -- however that said -- in my opinion even getting them is a miracle.

------

My solution -- always been the same -- a different cadre for identified high tech research companies with GoI, with a different pay scale etc.. different rules with more risk-reward binding. Allowance for lateral intake etc.

Sort of like Navratna++; owned by GoI operated like Private.

No short cuts to fundamental problems -- there should be a working institution, counting on miracles to happen is not planning. (and getting people motivated to slog their life for peanuts in the name of the country is not a sustainable organizational building approach either)

-------

(I am not in favor of moving out the complete product development to private companies, we will instead of Natasha's then talk about Ayesha's and Gulabo's, just like in US of A, of crony capitalism and media tripartite battles like Ambani brothers -- given what such moves do the the politicization of armed forces procurement as well as the efficiency of procurement -- as well the corrupting impact of a war economy based society -- as well as the ease of making that move by GoI)

geeth · Post by **geeth** » 24 Aug 2009 15:03

Narayanan,

While we can always blame the GTRE guys about their work ethics, there are many other factors which has resulted in such a sorry state of affairs.

We have been repeating the points and counter points over the past many years. It is now too boring to say it all over again.

I am sure your few posts above are also a repeatition of the past. No point in talking more about it.

The fact remains that the facilities available are not good enough for a top rated engine programme. If the money supplied (about 2800 cr or so) is enough for ONE engine programme, where is the question of spending for additional experimental engine programmes?.

If the calibre of the people there is not top notch, then some of the blame should be borne by the engineers passing out from top institutes - they used to have a fascination for working in firangi organisations (don't know now) - I know it is a chicken and egg case. Lack of facilities here, we go there ; you go there and not so good people have to do the doney work back in desh.

No matter how slow we go, We still will reach there - beg, borrow (but not steal

)

I saw a tender from DRDL about a year back for a Hypersonic wind tunnel, which is AFTER the test flight of AGNI III. I don't know if the babu's got convinced about the need only after the missile was fired and proved. Same is the case with many other organisations.

Back to Kaveri, there is a lot of design improvements required for the Kaveri Compressor blades. NAL had taken up some work and redesigned the blade profile, resulting in slight performance from the first series, but, to my knowledge, the facilities at NAL are woefully inadequate for any serious improvement in the performance of the compressor.

Sanku · Post by **Sanku** » 24 Aug 2009 15:06

Forget Hardware requirement, they dont have the budget and the system to hire the whole bunch of DOOs and PIGs that are needed for the raw writing of code.

I have some idea of what it takes to put together a 200,000 line CFD program.

Raj Malhotra · Post by **Raj Malhotra** » 24 Aug 2009 16:27

GTRE is a mess and misused or non-used even limited funds given by GoI. Having said that trying to develop a contemporary engine for US$ 100 million is a joke. Note the big funds have just come recently, and I wonder whether they have even been disbursed. It is failure of Babu to realise that Kaveri is not only for LCA but will lead to family of engines with addition to economy of almost US$ 2-5 Billion dollar per annum.

enqyoob · Post by **enqyoob** » 24 Aug 2009 17:18

Thanks to all. The point of the discussion (I blame RahulM entirely for disturbing the peace and forcing me to write on the EllCeeYa - and I can't write more than just hinting, about certain other parts of EllCeeYa that also need writing about, so I pick the injin SNAFU (That's Supersonic Nozzle w/ Augmented Fuel Utilisation, for the Pure Oxbridge Angreji buzzword crew - Top Secret Feature of Advanced Kaveri-19 model).

All that one can hope 2 do is:
1. Point out very clearly that, however much we may wish things were otherwise, the PR coming out of the Kaveri program is 400% BS. "Flat-rated", "supercruise", "uniquely designed for Highly Diverse Indian Conditions" - the evidence does not support any of these as being anything other than PR department inventions.
2. India is not advancing in gas turbine technology - we are falling behind by the same rate as the passage of years. Today we are about at 1970, so we are 39 years behind. Next year we will be at 1970, so we will be 40 years behind.
3. The reasons for the present design parameters of the Kaveri can be found in the above two points.
4. However, one reason why the present managers may be persisting with the overall engine dimensions, number of stages etc. may be a forlorn hope that miraculous injections of technology will boost the pressure ratio and turbine inlet temperature, and allow an expansion of the fan stages to enable decent bypass ratio, more thrust and much better fuel efficiency.
5. GTRE is the only organization mandated and established by Constitutional authority to advance Research on gas turbines in India. So that HAS to be where the finger is pointed, and THEY can try explaining why things are in today's shape, and what they are doing about it. IMO the time for such explanations will come again when they are absorbed into some new entity that is actually empowered and charged to move ahead on both short and long-term basis.
**********************************

So far we have seen:
1. Technology Sanctions are NOT the primary reason for the backwardness. Poor organization, planning and execution, and lack of any long-term will, is much more important.
2. GTRE has simply failed to excite much support.
3. It appears that GTRE gambled on the non-induction of the LCA, rather than move ahead to be ready for it.
4. There is credible evidence (from experienced ppl) that GTRE failed to bring in the help of experienced engine production people and instead got amateurs to try producing and assembling jet engine prototypes, and this may be a primary reason for performance not coming anywhere near what the designers may have predicted. This aspect requires much deeper and bloody-minded investigation - it may be a sign of non-cooperation by other entities, or some huge arrogance and inattention on the part of GTRE top leadership.
5. Given the above, the excuse about lack of test facilities is not credible. There are engine production plants, and airline maintenance facilities in India. There are plenty of test cells, even in B'lore.
6. The lack of test equipment (for instance, to detect modes of unsteadiness) is also a false excuse. Vibration monitoring / System Identification equipment is as simple as accelerometers, Fast Fourier Transform chips (or software, perfectly adequate), analysis software and a good user interface. Going abroad to get such tests is HIGHLY questionable.
7. The lack of high-altitude testing facilities is also a bogus argument. A vacuum chamber for testing is not at all a difficult thing to build, in a nation that builds nuclear reactors and ship hulls that can take much worse pressure differences and buffeting. Putting a test engine on the wing of a transport aircraft and flying it at altitude is not such a difficult thing either. The amount of money and delay spent on doing these things abroad, should be questioned. Why was there no planning to get these things prepared with enough lead time in India? So OK, one or two tests are done abroad, now what's the hangup in doing them in India?

So these are the purposes of the discussion.
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Vinaji: Yes, now v r on same wavelength onlee.

Because of all the improvements at the component levels (not surprising really, because of the massive research that went into materials and the subsonic and achiveable/practical supersonic regimes, rather than more exotic very high machs) , now the conventional engines have imbrooved to such a point that you can have a massive majority of hallal stuff in the mix and very little of haraam. So effectively you are saying that the point at which you will have to consider going into more "turbojet" cycles and at higher mach "ramjet" cycles has shifted away to much higher speeds than back in the bell bottom days!.

Exactly. So if the Kaveri ppl tell the unsuspecting public that they r doing lo-piebass due to deep planning for the High Mach Number Ell Cee Ya, they r, shall v say, on full afterburner.

But surely this part has to be very easy no ?

Quote:(develop swadeshi codes and validate them for tough new configurations, jump ahead).

With all those DOOs and PIGS around, it is very easy to get this done in a span of 3 years or so. Tell the PIGS in the top 5 Madrassa branches that there are "motivational" toffees around (ie No reccos, references to fly to videsh if you dont do good).. You can parcel it out to each madrassa by area (one for compressor, one for combustion etc.. etc).. PIGs will love it and Oink with pleasure. After all, PIGS need to do project in 8th sem and most of 7th sem and are usually on a haze of intoxicated smoke (either from tobacco or from stuff growing in Idukki or both) . So in 3 batches of PIGs , with decent IT/Vity project management , you can have top of the line stuff and can catch up with anything out there today in terms of analysis and design tools!.

You will have all the CFD codes for flow right from modeling the Euler flow with full inviscid stuff and no linear approximations and all the statistical thermodynamic stuff for combustion, high temp gas dynamics etc and also the CFD and FEA for mechanical design .. Very halaal only.

Strange if GTRE and other orgs have such program. I remember 80s PIGS writing combustion /grain burn pattern modeling programs for ISRO for Rs 150 or so a pop!. PIGs love such carrots / sweeteners.

EXACTLY my point. But it requires some awakening by the PIGS' and PIUS' maulanas in the madarssas. Right now it seems all they 4 doing is Reading the Good Book (Hill & Peterson, or if that is too difficult to solve the problems, then some watered-down text) to said PIGS and PIUS, and they come away happy at all the buzzwords they have learned.

I have the following insult to hurl: Circa 1977, the eye eye tea madarssa had a grand total of 1 EyeBeeEm computer with card punch and CRPF with 0.303 rifles outside. In those days, it was feasible to develop a FORTRAN program to do 1-D analysis of all the things that vinaji mentioned - ramjet-2-turbofan , and with 2-D multi-ramp shock inlet etc. By a PIU with only one course in FORTRAN taken as part of a Numerical Analysis course.

Todin it can be done on Excel.

HOW MANY PIGS AND PIUS CAN AND HAVE DONE THAT IN the madarssas these days?

(Hint: I c quite a few hu come by with CVs full of FLUENT, EFFLUENT etc. and have a good idea of the answer to the above..)

Sanku · Post by **Sanku** » 24 Aug 2009 17:32

narayanan wrote:Exactly. So if the Kaveri ppl tell the unsuspecting public that they r doing lo-piebass due to deep planning for the High Mach Number Ell Cee Ya, they r, shall v say, on full afterburner.

This is exactly where thing start unravelling. Who is the unsuspecting public

since when did any GoI run on the guidelines of the unsuspecting public? Are all the Engine designers only within GTRE? And no one else understands engines in the country? (apart from Narayananan of course

)

If not (and clearly not) why has the entire setup not raised a pip about it? What happened to all the check and balances and the MoD and top level planning etc? Why does some one not go up to GTRE and say "you know you dont need to take your engines to Russia, we can do it here, now stop cribbing", where is HAL when GTRE says, hey we need test beds for engines but there are none of the quality we need in India. Where does ADA's role come in when it is supposed to be "NODAL" agency for LCA?

Even you acknowledge that there should be development in materials in parallel. Now while you can blame GTRE for not doing their CFD, cutting open more engines to get their blade and compressor shapes. (Run the whole thing into a laser based profiling system and just reverse engineer the shape hey?) trying to understand the shock formation etc etc.

How can you also not look at the fact that they have no materials to work with largely anyway.

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And finally as I said before, whats the expectation to do better? When we can barely make a Tank with 60% imports with a engine not from India and that is considered pretty cool and IA be damned if they dont take what ever they are given, why not extended the grace to GTRE? Hain jee?

There are fundamental mess ups with the way R&D is done in India, and just because ISRO was lucky to have a Sarabhai in 50s and performed miracles with their limited starting point does not mean that we raise the bar for miracles to every govt institution.

Engines need a full ADA-Engines like setup and similar funding (as much as rest of LCA) -- if you try and make do with GTRE -- be happy with the Kaveri.

rajsunder · Post by **rajsunder** » 24 Aug 2009 21:26

One question to the learned folks

cant we simulate the high altitude tests on the ground in a pressure controlled chamber ????

bala · Post by **bala** » 24 Aug 2009 21:55

The questions on GTRE/HAL/ADA management goes to the root of the problem. The DRDO Chief M. Natarajan is wholly to be blamed. His stewardship lacks vigor and vitality in the organization. A national program like the LCA cannot be left floundering for an engine. There is no lack of talent in the nation but the programs to drive the talent pool to a desired goal is lacking. Maybe the Indian Navy should be incharge of the LCA/Kaveri program, they will make things happen like the Arihant or the gas turbine for the ships. Someone needs to be in charge of kicking the barn doors.

Materials and testing are highly lacking in the current setup. Buzzwords and theory abound, when practical working models are required. For their part, the IITs and NITs can shoulder the theory and practical sub working models. Dealing with high temperatures and pressures requires a different mindset. Every minute component of the aircraft engine is engineered for high performance. The suppliers of parts need a quantum upgrade in technology and material and manufacturing processes. This is not a walk in the park, it requires due diligence and hard work.

Drevin · Post by **Drevin** » 24 Aug 2009 22:11

why so serious about what went wrong. its been a joke for a long time. who will believe a turbofan development project didnot create a design that was supposed to take care of weight increases in the aircraft it was meant for.

Initial project goal setting is the problem. guys involved during that phase are prolly not in gtre anymore.

ncube sir tried to make everyone smile by saying that gtre didnot expect ada-nal to actually deliver a beautiful plane.

i am in chill mode regarding the kaveri for ages now.

enqyoob · Post by **enqyoob** » 24 Aug 2009 22:25

cant we simulate the high altitude tests on the ground in a pressure controlled chamber ????

You need a powerful electric or diesel pump to pull the air out of a big chamber, along with taking out the exhaust from the engine during the testing. But consider that you only need to maintain a 1 atmosphere pressure difference, so I don't see what is so tough about building the chamber itself. Getting the temperature down to the level of upper atmosphere may be harder, but I think it can be done with some dry ice or liquid nitrogen running a heat exchanger with the facility air. Upper atmosphere is only 217K (-56C) - isn't dry ice -80C?

Evacuating a large chamber volume is only for the tests where the inlet is an issue - for other tests, they just connect a pipe to the inlet and maybe an exhaust pipe to the exhaust.

ramana · Post by **ramana** » 25 Aug 2009 02:36

So the short answer to why Kaveri doesn't power the LCA is that it was designed violating thermodamnics. And tomake it work need unobtanium (SCB).

And all this time we were fed stories of it being round the corner.

What part of it can be salvaged?