Kaveri & Aero-Engine: News & Discussion

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habal
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Re: Kaveri & aero-engine discussion

Postby habal » 15 Apr 2018 10:25

So Kaveri was success (partial-almost) post remedial measures after Russian flight test, but was scrapped just when it neared completion to take out the complete indigenous option from emerging to compete for Indian air force requirements which was/is suffering from heavy attrition.

reasons can be many:

1. Little opportunity for kickbacks with Indian option.
2. Concession to USA as to we can be good US poodle.
3. CBM with pakistan as complete aircraft+engine systems transforms us into different league uninterested in any talks for territory.
4. Continue in western camp and bribe them with contracts for a/c tech and airframes.
5. Indian population tied to western corporate interests as slavish subservience terms for foreign investment and India continues to spend capital on western tech endlessly Y-o-Y

2 seems unlikely only because China has already taken a huge leap by putting all their und development engines on flight test or on airframes and thus taking huge technological leap in experience. India lagging so far behind will only hurt Indians and not benefit USA wrt India-China future strategic gap. Indian leadership should be wary of not becoming a technically deficient pakistan clone only barking at neighbours in future.

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Re: Kaveri & aero-engine discussion

Postby suryag » 15 Apr 2018 13:51

Not that am batting for dr.t.mohana Rao under whom the Kaveri was almost a success with flight test done in 2009 and fixes made thereafter but he got netted in the massage parkour raid in 2011

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Re: Kaveri & aero-engine discussion

Postby vina » 15 Apr 2018 14:42

Dang . I am making heavy weather on typing out the "solution" /"fix" for the Kaveri. I am crunched on time, racing to tie things up before I head out to Europe on vacation this friday with family etc. However, good thing is that the full engineering analysis and number crunching is all done, and actually it came out very well. I would have been very proud to put up this stuff for a final theses either in an undergrad or a master's program and would have loved defending it in front of a committee. But anyways, I will post the "Executive Summary" from the write up that is a WIP. I haven't finished tying out everything , which I hope to do in a day or two and mail it out to a set of people who I hope will do something about it.

https://forums.bharat-rakshak.com/posting.php?mode=quote&f=3&p=2240840
chetak wrote:Have you heard of water injection during take off?? There is actually lots to wonder about

I wrote what I wrote in my earlier post to you VERY carefully. It is as if I took it out of your mouth , literally . This fix just popped into my head just after I read the GTX paper that was posted here, and I said to myself, gosh.. these guys should actually look BACKWARDS in time and not FORWARDS for a fix. So thats what I did by working "backwards" . None of this unknown to you or your former colleagues of course! The "fix" is below.

Code: Select all

Folks, PLEASE note that this is pretty serious work, not a stuff that got typed up over a few seconds. It required actual work and it is a tailored analysis for the Kaveri. It is NOT off a book or a brochure. It is backed by serious top notch engineering data , hard theoretical and experiemental stuff and is I repeat serious stuff. I will post the full document once I finish typing it out and send it out to first and share the link here .DO NOT COPY WHAT IS WRITTEN HERE AND POST IT around. 


EXECUTIVE SUMMARY
India has been engaged in developing an engine (Kaveri - GTX 35 VS) for the Light Combat Aircraft (LCA) program since the late 1980s. The Kaveri engine is a “Flat rated engine with particular reference to the Indian operating requirements of good dry combat performance at low level, high speed and high ambient condition”, that employed the “variable cycle ratio, high cycle temperature throttle ratio concept”, as described in the concept paper from GTRE/DRDO [1].
The GTX concept optimises the Kaveri engine for high speed, high altitude and high ambient temperature conditions by throttling the turbine entry temperature (TET) of 1700K to 1400 K the sea level static thrust (SLS) design point in standard conditions. However, the trade off in this optimisation is that the engine develops lesser Net Thrust in the takeoff and initial climbout flight modes than otherwise possible.

While the Kaveri engine seems to be able to deliver it’s designed dry and augmented reheat ratings, the weight growth in the operational LCA fighter- Tejas, by the order of 1.2 tons has meant that the Kaveri engine is no longer useable its current form in the Tejas fighter as there will be a serious shortfall in SLS thrust for take-off and climb-out performance.
There is therefore an immediate need to enhance the thrust of the Kaveri engine to make it useable in the Tejas fighter (Mk2 version) and derive growth options of the engine suitable for follow on programs (AMCA and others). To address the thrust shortfall, GTRE/DRDO seem to be looking at new high temperature materials and collaboration with foreign engine houses. This however, is a longer term plan that is subject to uncertainties around material development and qualification and dependency on the collaborator and likely to lead into a cul-de-sac.
A proven fix for the Kaveri engine that is not dependent on materials development and foreign collaboration is available and easily implementable in a very short time frame.
Water/Methanol-Water injection is an old scheme of thrust augmentation that goes back to WW II and was extensively used since then during the early jet age until the late 1970s both in the civil and military sides, when Turbojets were in use. This augmentation was almost always solely for take-off and climb-out. These flight regimes are precisely where the Kaveri and its turbojet cycle falls short of what is required. Hence water injection (simultaneously with the reheat thrust) can remedy the thrust shortfall in the takeoff and climb out flight regimes, while the strengths of the GTX cycle in the other flight regimes for which it is optimised may allow the engine to remain competitive and be used in an operational fighter.
This study analyses the options for Water Injection in the Kaveri engines, performance gains in each option, ease of implementation, growth potential and weight implications of using the Tejas for take-off and climb-out flight regimes.
The study used the seminal papers in the area of water injection in Turbojet engines, the methodologies and basic data from NACA [2] [3] [4] , engineering comparisons and approximations based on the Harrier , an in service plane that uses water injection to arrive at performance, systems and weight estimates. In addition water / methanol-water injection systems that have served in IAF colours namely Mig-25, Mig 23 and Mig 27 were also studied.
The study found that with water injection in the current Kaveri engine, a thrust increase between 12% to 20% i.e. an engine with a water injected thrust between 57 KN to 64 KN without reheat and 86 KN to 91.4KN with reheat can be achieved as a baseline. This will require between 144 kg to 175 kg of water for a total of 90 second use) and can be carried in the void space that currently exists in the fin of the Tejas .The fin can be made a wet-fin with tanks for water and fuel, like was done for the SU30 versions for China and Malaysia. The possibility exists of incorporating a “high power combat mode” where the system could deliver very high peak power for limited duration via water injection, like the system available in the Mig-21.

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Re: Kaveri & aero-engine discussion

Postby JayS » 16 Apr 2018 11:30

ArjunPandit wrote:
JayS wrote:
But their engines are firmly in and are in for a long haul. Thats still a significant leverage. Unless we break the jinx with Kaveri we will be tied one way or the other.


JayS sir,
how much can the engine sanction affect us?An engine has even if russian has 1000 hour life (rough figures from Su30mki). That would mean a lot of time before an engine will be replaced. Also, didnt Iranians maintain their F14 fleet for long.


No Sir please.

We can keep ourselves immune from sanctions provided we stack up all spares for good long years (say 30yrs) (or acquire MFG capability of some components and stack up others which GE wouldn't give ToT for), when times are good and learn how to do all the MRO without OEM support (I think we can already do this vis-à-vis F404, as complete integration and qualification of F404 was done without help from GE post 1998 sanctions). But we are not particularly knows for looking into future and long term planning are we..? Its not un-doable or particularly difficult to do IMO. But I think there are high chances our guys will fail to do it.

Re the Iranian F14, I have heard this many times, but I would like to know what was the real combat efficacy these jets had, with and without OEM support. How they performed during war, if they did so. I do not know much of this particular subject. Anyhow its OT here.

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Re: Kaveri & aero-engine discussion

Postby Pratyush » 16 Apr 2018 12:09

The best way to be sanctions proof is to complete Kaveri and put it in production. Everyone else can place sanctions oo us. Or demand and arm and a leg to provide support during times of crises.

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Re: Kaveri & aero-engine discussion

Postby habal » 16 Apr 2018 12:36

It is never possible to stock up on spares, because even GE knows which are mission critical spares and can restrict or trickle supply such spares to client. They can sense your motives in stocking up large amount of spares and can restrict supply that just meets a few months attrition on some excuse or another. Only guarantee against such mischief is that we have plenty of other platforms to fall back on, and in light of that GE doesn't want to unnecesarily sully their reputation.

It is important we do NOT field hundreds of Tejas with only GE engines because then US pressure WILL come into play. Not more than 50-100 Tejas should have GE engine.

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Re: Kaveri & aero-engine discussion

Postby JayS » 16 Apr 2018 12:47

habal wrote:It is never possible to stock up on spares, because even GE knows which are mission critical spares and can restrict or trickle supply such spares to client. They can sense your motives in stocking up large amount of spares and can restrict supply that just meets a few months attrition on some excuse or another. Only guarantee against such mischief is that we have plenty of other platforms to fall back on, and in light of that GE doesn't want to unnecesarily sully their reputation.

It is important we do NOT field hundreds of Tejas with only GE engines because then US pressure WILL come into play. Not more than 50-100 Tejas should have GE engine.


That GE will throttle critical SS is a remote possibility as of now, in current scenario. I am talking about buying SS in next 5yr of so time frame, which would last for next 30yr or so. We can always link the initial contract with assured buy of so many number of SS and buy the spares along with the engines themselves. Or we can buy additional engines and cannibalize them in dire times. It will be a costly proposition of coarse. If we formulate the contract right and pay the mullah for it, there is no particular reason GE will throttle SS supply or refuse to sell us more engines when US-India relations are not strained. GE is looking for much more than LCA related contract. If they screw up now they will never get contract for AMCA, especially with already skeptical IAF. We can use this to our advantage.

But I am pretty sure we will not do all this.

Kaveri is the way forward and that's a no brainer. But as of now, we should be worried of keeping our Tejas fleet operations under any circumstances, which is going to be powered by GE engines. Kaveri, when comes, it can supplant F404. But until then plan B is needed. We need to work on multiple fronts. Doing only this or only that is not an option.

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Re: Kaveri & aero-engine discussion

Postby habal » 16 Apr 2018 13:01

best strategy would be to compartmentalize Kaveri incremental development into various mettalurgy giants from pvt sector such as L&T and Kalyani, Tata Steel etc and give each one a specific component to improvise based around the Kabini core. So say let Kalyani take up LP, L&T take up single crystal blade and afterburner and Tata Steel another critical component within a 1-2 yr timeframe and integrate it to make finished product. The main idea being not to let critical areas like mettalurgy to just gtre or drdo but use more dynamic and quick reaction times of pvt giants to tide over bureaucratic stasis in material development.

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Re: Kaveri & aero-engine discussion

Postby JayS » 16 Apr 2018 21:30

Madhu,

here is a summary of the Kaveri parameters from my set of calculations. I am yet to do the stage matching and thus the W numbers are out of sync. But I realised that the specified PR values cannot be taken as constants and would need to be varied to converge the calculations.

This is for uninstalled thrust. The SFC values are on higher sides. I need to fine tune the model further.

Image

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Re: Kaveri & aero-engine discussion

Postby vina » 17 Apr 2018 09:56

JayS wrote:Madhu,

here is a summary of the Kaveri parameters from my set of calculations. I am yet to do the stage matching and thus the W numbers are out of sync. But I realised that the specified PR values cannot be taken as constants and would need to be varied to converge the calculations.

This is for uninstalled thrust. The SFC values are on higher sides. I need to fine tune the model further.

Just posting this from the figures that I have from my spreadsheet & calculations.
The fan exit temp I have is 426.79K, with an eta (assumed) of 0.85
HPC exit temp is 776.43K (eta of 0.85)
The TSFC of the current Kaveri is 23.63 g/KNs per my calculation. This is very close and in the ball park of EJ200 dry thrust figure of 23 g/KNs. I think my calculated numbers are good. The number you have for TSFC (dry) is around 26.3 g/KNs , which seems off by around 10% . The TET should be limited to 1400K in ISA conditions as per the GTX cycle.

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Re: Kaveri & aero-engine discussion

Postby JayS » 17 Apr 2018 11:25

vina wrote:
JayS wrote:Madhu,

here is a summary of the Kaveri parameters from my set of calculations. I am yet to do the stage matching and thus the W numbers are out of sync. But I realised that the specified PR values cannot be taken as constants and would need to be varied to converge the calculations.

This is for uninstalled thrust. The SFC values are on higher sides. I need to fine tune the model further.

Just posting this from the figures that I have from my spreadsheet & calculations.
The fan exit temp I have is 426.79K, with an eta (assumed) of 0.85
HPC exit temp is 776.43K (eta of 0.85)
The TSFC of the current Kaveri is 23.63 g/KNs per my calculation. This is very close and in the ball park of EJ200 dry thrust figure of 23 g/KNs. I think my calculated numbers are good. The number you have for TSFC (dry) is around 26.3 g/KNs , which seems off by around 10% . The TET should be limited to 1400K in ISA conditions as per the GTX cycle.


Thanks. Yes as I said I need to fine tune the model. Both SFC values are off by quite a bit. And there is no stage matching. I have modified some of the constraints in new model yesterday. Still need to add more. And need to include blade cooling model too. As of now its just primitive model with assumption that cooling flow reached HPT exit conditions without losses. No account of accessories work off take which is like 10% of HPT output. And some more details.

Some of the difference in your values and mine would be due to differences in Cp and Gamma values. I need to encode them as polynomial function of T. As of now I just took aprox numbers from a table.

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Re: Kaveri & aero-engine discussion

Postby madhu » 17 Apr 2018 13:52

JayS wrote: And there is no stage matching.

Yes I agree as now Pt2/Pt6 is around 1.2 which is way too high. It has to be too around 1.05
vina wrote: The TET should be limited to 1400K in ISA conditions as per the GTX cycle.

I am still not able to get my head around with this TET. I feel it is too low TET to be realistic. At latitude if we do the same calculation the TET will fall way below which to me is odd. I still believe that our TET has to be 1700K. any reference is there for this low number?

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Re: Kaveri & aero-engine discussion

Postby JayS » 17 Apr 2018 15:56

madhu wrote:
JayS wrote: And there is no stage matching.

Yes I agree as now Pt2/Pt6 is around 1.2 which is way too high. It has to be too around 1.05
vina wrote: The TET should be limited to 1400K in ISA conditions as per the GTX cycle.

I am still not able to get my head around with this TET. I feel it is too low TET to be realistic. At latitude if we do the same calculation the TET will fall way below which to me is odd. I still believe that our TET has to be 1700K. any reference is there for this low number?


I am feeling lazy today. So please see a few pages ago, I think it was jaysimha who posted a paper on Kaveri Flat rating. You can easily find on google too.

For Kaveri, TET varies between 1400K-1700K. Thrust decreases as you go higher up from SL. They limited TET to keep thrust on lower altitudes limited to max design thrust. TET is hiked as altitude is increased. At some altitude say 10000ft, the TET hits 1700K and produce same thrust as it was on ground. After than point TET is kept at 1700K and thrust is allowed to drop.

I have not given a careful thought so far as to what exactly the TET should be at ISA conditions for uninstalled thrust. But it will be definitely lower than 1700K and possibly 1400K or at least closure to 1400K.

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Re: Kaveri & aero-engine discussion

Postby ashishvikas » 17 Apr 2018 19:53

Ok, the GTRE folks I spoke to say that the six main design issues with the Kaveri engine have mostly been solved now, either in-house or with foreign inputs. Apparently, screech is not an issue anymore.

https://twitter.com/SJha1618/status/986 ... 51808?s=19

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Re: Kaveri & aero-engine discussion

Postby JayS » 17 Apr 2018 21:52

^^ I have been saying the exact same thing since last Aero India.

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Re: Kaveri & aero-engine discussion

Postby hanumadu » 18 Apr 2018 11:35

ashishvikas wrote:Ok, the GTRE folks I spoke to say that the six main design issues with the Kaveri engine have mostly been solved now, either in-house or with foreign inputs. Apparently, screech is not an issue anymore.

https://twitter.com/SJha1618/status/986 ... 51808?s=19


Now what are the figures for the thrust?

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Re: Kaveri & aero-engine discussion

Postby Shankk » 18 Apr 2018 17:56

https://twitter.com/SJha1618/status/986457503369170945

DMRL developed 2nd Gen single crystal blades some years ago itself.

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Re: Kaveri & aero-engine discussion

Postby Haridas » 18 Apr 2018 19:51

Shankk wrote:https://twitter.com/SJha1618/status/986457503369170945

DMRL developed 2nd Gen single crystal blades some years ago itself.


11 yrs ago at Aero India they showed indigenous SCB.

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Re: Kaveri & aero-engine discussion

Postby Haridas » 18 Apr 2018 20:44

Wet power augmentation should help Kaveri to power in to weight gained TEJAS MK2.

For AMCA whose airframe is being designed (unlike the evolved heavier TEJAS MK2) what prevents GTRE/DRDO from developing a scaled up version of Kaveri where the dry thrust is factored up to say 80kN? T/W ratio will only improve going forward, and nothing is to say AMCA (like all new a/c designs) will also gain weight due to scope creep and design/technology shortfalls?
Last edited by Haridas on 19 Apr 2018 11:07, edited 1 time in total.

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Re: Kaveri & aero-engine discussion

Postby JayS » 18 Apr 2018 20:51

Funding is pending clearance for last 3-4 yrs. I had posted quite a bit of details from various Parliamentary committee reports.

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Re: Kaveri & aero-engine discussion

Postby habal » 19 Apr 2018 10:47

We have no way of knowing if the Kaveri is already doing duty with a MiG-29 unless the concerned agencies are allowed to disclose such info to the public. Makes no sense otherwise that the Kaveri has completed all tests and all issues have been resolved atleast 3 years ago and the engine is lying idle in some gtre warehouse. Can't really believe all that. Anyways the rate at which MiG-29/k engines get overhauled I think kaveri could well have got into one of them even before full testing was over.

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Re: Kaveri & aero-engine discussion

Postby vina » 19 Apr 2018 12:40

Okay finished typing it up. The full write up is Water Injection For Enhanced Thrust and Future Growth of GTX type Gas Turbines .

Have sent it out to "big folks" who I think are involved in this that I could find email ids for. Not sure if those emails are even active and if anyone even reads those emails. Thats fine though, it is been sent out and I am putting it here as well so that anyone interested can look it up, if nothing else from an engineering/learning/academic perspective. Check out the references and the stuff they did back in those days though. Absolutely foundational but simply back breaking and painstaking work . The kind of work upon which the entire superstructure of these kind of things were built on in the west.

Keep in mind the following while reading the write up.

1. Turbojets are sized for take off thrust. The Kaveri too is sized for that , as per the "original weight estimates" of the LCA. Since it is a turbojet, it is a large sized engine (compared to the turbofans that get put in today, 78 kg/s vs 65 kg/s). Not surprising , given that Turbojets will have lower Net Thrust (SLS , M0, H0) than Turbofans. With the growth in the LCA weight by close to 1.5 tons, the Kaveri means in current form is not useable as it will have less than required take off and climb out thrust
2. The Turbine Entry Temperature hit the limits during take off and initial climb phases. These are the "most demanding" on engines phase of flight . TET rarely is a big limiter in normal conditions of cruise , dash etc..

Kicked this stuff out of the door just in time. Off on vacation. Ta Da. ..

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Re: Kaveri & aero-engine discussion

Postby habal » 19 Apr 2018 13:14

vina saar, when did kaveri turn into a turbojet ?? Water at high altitude reminds me of Junaid Jamshed's plane that had crashed due to icing at high altitude resulting in propeller malfunction. Some heater supposed to keep propeller blades above certain temp had malfunctioned resulting in icing. So won't that be a hassle in this case too. One more thing to take care of and one more potential risk factor

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Re: Kaveri & aero-engine discussion

Postby nachiket » 19 Apr 2018 13:28

habal wrote:vina saar, when did kaveri turn into a turbojet ?? Water at high altitude reminds me of Junaid Jamshed's plane that had crashed due to icing at high altitude resulting in propeller malfunction. Some heater supposed to keep propeller blades above certain temp had malfunctioned resulting in icing. So won't that be a hassle in this case too. One more thing to take care of and one more potential risk factor

Water injection has been used to temporarily increase engine thrust for along time. In jet engines it is usually injected just before the combustion chamber where the fuel air mixture is ignited. It has no relation to engine icing which is caused due to atmospheric conditions which lead to ice deposits developing on engine inlets and fan blades.

Vina guru is recommending water injection during takeoff and climb phases (when high thrust is required) not at high altitude.

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Re: Kaveri & aero-engine discussion

Postby JayS » 19 Apr 2018 15:18

vina wrote:2. The Turbine Entry Temperature hit the limits during take off and initial climb phases. These are the "most demanding" on engines phase of flight . TET rarely is a big limiter in normal conditions of cruise , dash etc..
..


That's not true. Not generally at least. TET is a very real limiter for thrust at altitude.

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Re: Kaveri & aero-engine discussion

Postby arun » 19 Apr 2018 15:56

Haridas wrote:
Shankk wrote:https://twitter.com/SJha1618/status/986457503369170945

DMRL developed 2nd Gen single crystal blades some years ago itself.


11 yrs ago at Aero India they showed indigenous SCB.



Hmmmmm :-? ……….. and yet ………… in the recently put out Request For Information For Procurement Of {110} Fighter Aircraft For The Indian Air Force under the “Key Technology Domain” of Engine the first of the “Technologies Sought’ is:

(a) Single Crystal Blade Manufacturing Process.

The others “Technologies Sought” are:

(b) Blisk (Blade integrated with Disk) machining process.
(c) Directionally Solidified (DS) castings technology.
(d) FADEC and Sensors Technology.
(e) High strength thin walled Aluminium investment castings.
(f) Precision Blade Forgings.
(g) Linear Friction Welding.
(h) Profiled Rolled Rings –Near Net Shape.
(i) Electron Beam Physical Vapour Deposit (EBPVD) and Directs Vapour Deposit (DVD) Processes.
(j) Multi-axis Shot Peening.
(k) Laser Shock Peening process for high stress areas.
(l) Design & Manufacture of Wide Chord Fan.
(m) Variable Exhaust Nozzle actuation for straight and vectored thrusts application.
(n) Variable cycle engine technology

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Re: Kaveri & aero-engine discussion

Postby Indranil » 19 Apr 2018 18:42

Integration of Manik engine with Nirbhay has begun. GTRE has sent out a tender for the manufacturing of the engine bay. This will be completed in 120 days.

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Re: Kaveri & aero-engine discussion

Postby JayS » 19 Apr 2018 19:25

arun wrote:
Haridas wrote:
11 yrs ago at Aero India they showed indigenous SCB.



Hmmmmm :-? ……….. and yet ………… in the recently put out Request For Information For Procurement Of {110} Fighter Aircraft For The Indian Air Force under the “Key Technology Domain” of Engine the first of the “Technologies Sought’ is:

(a) Single Crystal Blade Manufacturing Process.

The others “Technologies Sought” are:

(b) Blisk (Blade integrated with Disk) machining process.
(c) Directionally Solidified (DS) castings technology.
(d) FADEC and Sensors Technology.
(e) High strength thin walled Aluminium investment castings.
(f) Precision Blade Forgings.
(g) Linear Friction Welding.
(h) Profiled Rolled Rings –Near Net Shape.
(i) Electron Beam Physical Vapour Deposit (EBPVD) and Directs Vapour Deposit (DVD) Processes.
(j) Multi-axis Shot Peening.
(k) Laser Shock Peening process for high stress areas.
(l) Design & Manufacture of Wide Chord Fan.
(m) Variable Exhaust Nozzle actuation for straight and vectored thrusts application.
(n) Variable cycle engine technology


That's just about everything under the Sun. Its RFI, so may be OK.

One should see what China is doing. While we are going door to door with a begging bowl, they have a coordinated efforts in buying out key base technology companies which are largely unknown in general. The other day I saw an example how 4 seemingly unrelated Chinese companies quietly bought 4 separate European machine tool companies which among them are the very foundation of that particular technology (IIRC AM related) in the world. These companies are rather cheap to acquire, a few hundred million $$ a piece. Well within capabilities of many of desi business giants. But we prefer to beg.

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Re: Kaveri & aero-engine discussion

Postby JayS » 19 Apr 2018 19:26

Indranil wrote:Integration of Manik engine with Nirbhay has begun. GTRE has sent out a tender for the manufacturing of the engine bay. This will be completed in 120 days.


Great news.

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Re: Kaveri & aero-engine discussion

Postby JayS » 19 Apr 2018 19:28

Re SCB Tech, I have posted details about level DMRL is at. They have cracked Casting. Two other key techs which are needed to get to the final blades are being worked on by MIDHANI.

ramana
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Re: Kaveri & aero-engine discussion

Postby ramana » 19 Apr 2018 19:36

Folks we have whine thread for whines.
Please stick to facts.

Indranil, Engine bay what is it? Test stand or engine integration facility?

arun, Its possible what is being sought is factory production technology.
SCB is demonstrated in the lab.


Now that 3D printers are being made in Bangalore, its possible to make (e) in India itself, with the melting pattern coated with ceramic and baked to leave the hollow cavity.

The key will be quality control of the melting, pouring and post casting processing.


JayS, What high strength Al casting alloys are made in India?

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Re: Kaveri & aero-engine discussion

Postby vina » 19 Apr 2018 19:59

Can the paper I wrote be hosted on BR? I will remove it from the drop box after I am back in town after another 2 weeks. I really so think a lot of stuff in that is something no one gave much thought of in India recently. Actually given the constraints they knew they had and the Indian operating conditions, the Kaveri was very prescient in many respects, especially stuff like variable cycle.

I made a prediction a couple of years ago and that came true. It was within the next 5 years the growth rate of india would surpass China's. Let me make another prediction. If we get our act right, we can have a functioning and optimized engine for a 5th generation plane in service before both the Chinese AND the Russians. For that we have to go a different route and delink the engine fro the latest materials. Our strategy should be to get the engine in first and back port the materials and other component level advances as and when they happen. We can do it. The Chinese can't and so the Russians. They need the materials absolutely to get the engines into service. They are locked on that path.

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Re: Kaveri & aero-engine discussion

Postby Prasad » 19 Apr 2018 23:16

vina wrote:Can the paper I wrote be hosted on BR?

We could host it on DDR if you like.

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Re: Kaveri & aero-engine discussion

Postby Haridas » 20 Apr 2018 06:54

vina wrote:Okay finished typing it up. The full write up is Water Injection For Enhanced Thrust and Future Growth of GTX type Gas Turbines .

Have sent it out to "big folks" who I think are involved in this that I could find email ids for. Not sure if those emails are even active and if anyone even reads those emails. Thats fine though, it is been sent out and I am putting it here as well so that anyone interested can look it up, if nothing else from an engineering/learning/academic perspective. Check out the references and the stuff they did back in those days though. Absolutely foundational but simply back breaking and painstaking work . The kind of work upon which the entire superstructure of these kind of things were built on in the west.

Keep in mind the following while reading the write up.

1. Turbojets are sized for take off thrust. The Kaveri too is sized for that , as per the "original weight estimates" of the LCA. Since it is a turbojet, it is a large sized engine (compared to the turbofans that get put in today, 78 kg/s vs 65 kg/s). Not surprising , given that Turbojets will have lower Net Thrust (SLS , M0, H0) than Turbofans. With the growth in the LCA weight by close to 1.5 tons, the Kaveri means in current form is not useable as it will have less than required take off and climb out thrust
2. The Turbine Entry Temperature hit the limits during take off and initial climb phases. These are the "most demanding" on engines phase of flight . TET rarely is a big limiter in normal conditions of cruise , dash etc..

Kicked this stuff out of the door just in time. Off on vacation. Ta Da. ..

Vina ji, Excellent paper. Good service to serve Bharat.
Some of us may have connections that may result in reaching the targeted audience. What is your wish list of people you would ideally like them to read this paper? Both technical/managerial and executives/bean-counters.

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Re: Kaveri & aero-engine discussion

Postby Haridas » 20 Apr 2018 06:59

nachiket wrote:
habal wrote:vina saar, when did kaveri turn into a turbojet ?? Water at high altitude reminds me of Junaid Jamshed's plane that had crashed due to icing at high altitude resulting in propeller malfunction. Some heater supposed to keep propeller blades above certain temp had malfunctioned resulting in icing. So won't that be a hassle in this case too. One more thing to take care of and one more potential risk factor

Water injection has been used to temporarily increase engine thrust for along time. In jet engines it is usually injected just before the combustion chamber where the fuel air mixture is ignited. It has no relation to engine icing which is caused due to atmospheric conditions which lead to ice deposits developing on engine inlets and fan blades.

Vina guru is recommending water injection during takeoff and climb phases (when high thrust is required) not at high altitude.


If one reads the paper more carefully it teaches how to handle water freezing issue (in tank). In fact just like it was handled in earlier aircrafts. Think of Mig-21, Mig23/27, no different. In cold countries there is also a thing called anti-freeze.

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Re: Kaveri & aero-engine discussion

Postby chetak » 20 Apr 2018 09:03

Haridas wrote:
nachiket wrote:Water injection has been used to temporarily increase engine thrust for along time. In jet engines it is usually injected just before the combustion chamber where the fuel air mixture is ignited. It has no relation to engine icing which is caused due to atmospheric conditions which lead to ice deposits developing on engine inlets and fan blades.

Vina guru is recommending water injection during takeoff and climb phases (when high thrust is required) not at high altitude.


If one reads the paper more carefully it teaches how to handle water freezing issue (in tank). In fact just like it was handled in earlier aircrafts. Think of Mig-21, Mig23/27, no different. In cold countries there is also a thing called anti-freeze.


The "water" used is demineralized water. It is used for a very specific reason.

Anitfreeze?? Defeats this very purpose and would cause irreparable damage to the engine.

There is however a non freezing mixture of water and alcohol that could be used.

Low or nil ash content is the critical thing for stuff burning in the engine :)

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Re: Kaveri & aero-engine discussion

Postby pravula » 20 Apr 2018 10:49

Cheapest antifreeze is a mix of methanol+water.

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Re: Kaveri & aero-engine discussion

Postby chetak » 20 Apr 2018 11:06

pravula wrote:Cheapest antifreeze is a mix of methanol+water.


need to test for ash content before use.

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Re: Kaveri & aero-engine discussion

Postby Pratyush » 20 Apr 2018 11:54

Why do we need antifreeze for Indian operations requiemnts. I would imagine that heat generated by gas turbine would be sufficient to turn ice into water for injection into the engine.

Besides do we know for certain that Kaveri will be using water injection for extra thrust?

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Re: Kaveri & aero-engine discussion

Postby chetak » 20 Apr 2018 12:15

Pratyush wrote:Why do we need antifreeze for Indian operations requiemnts. I would imagine that heat generated by gas turbine would be sufficient to turn ice into water for injection into the engine.

Besides do we know for certain that Kaveri will be using water injection for extra thrust?


Its just an idea that is being tossed around.

The proposed plan is to store the water in the tail/vertical fin section of the aircraft.

rapidly consumable weights stored at the extreme ends of the air frame may produce CG problems of its own, depending on the weight, of course and especially during combat maneuvering.


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