Kaveri & Aero-Engine: News & Discussion

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JayS
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Re: Kaveri & aero-engine discussion

Post by JayS »

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

Post by madhu »

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?
JayS
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Re: Kaveri & aero-engine discussion

Post by JayS »

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

Post by ashishvikas »

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
JayS
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Re: Kaveri & aero-engine discussion

Post by JayS »

^^ I have been saying the exact same thing since last Aero India.
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Re: Kaveri & aero-engine discussion

Post by hanumadu »

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

Post by Shankk »

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

DMRL developed 2nd Gen single crystal blades some years ago itself.
Haridas
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Re: Kaveri & aero-engine discussion

Post by Haridas »

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

Post by Haridas »

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.
JayS
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Re: Kaveri & aero-engine discussion

Post by JayS »

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

Post by habal »

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

Post by vina »

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

Post by habal »

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

Post by nachiket »

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.
JayS
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Re: Kaveri & aero-engine discussion

Post by JayS »

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

Post by arun »

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

Post by Indranil »

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

Post by JayS »

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.
JayS
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Re: Kaveri & aero-engine discussion

Post by JayS »

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

Post by JayS »

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.
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Re: Kaveri & aero-engine discussion

Post by ramana »

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

Post by vina »

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

Post by Prasad »

vina wrote:Can the paper I wrote be hosted on BR?
We could host it on DDR if you like.
Haridas
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Re: Kaveri & aero-engine discussion

Post by Haridas »

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

Post by Haridas »

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

Post by chetak »

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

Post by pravula »

Cheapest antifreeze is a mix of methanol+water.
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Re: Kaveri & aero-engine discussion

Post by chetak »

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

Post by Pratyush »

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

Post by chetak »

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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Re: Kaveri & aero-engine discussion

Post by JayS »

chetak wrote:
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.
Vina is proposing to use water injection only for TO and climb out. So the water tank wherever it is will be empty soon enough. (Surely during TO, there will need to be a small tweak to be needed in FCS though, but I think this should be fairly easy). Even in case someone wants to make fin a wet fin for fuel, that fuel should be consumed during idling/Taxing/TO itself. It will indeed need FCS modification otherwise. 100kg at ~5m from CG is similar to 500kG at CG. The fin itself will need modifications as its not fit for being a fuel/water tank as of now. Perhaps use of inner rubber fuel tanks can be made so that the composite structure itself would not need to be modified too much. Water is not good for composites. (In fact the very first composite usage in operational use is in Fins. Then, it was observed that they undergo fatigue failure due to water seepage as seeped water repeatedly freezes-liquefies when the aircraft changes altitude/Op conditions, widening cracks. The damage is typically undetectable from outside unless you do detailed NDT and this results in catastrophic failures one fine day.)

Main challenge would be to create the water injection system in the engine and related ducting in the aircraft. Had it been a fairly simple system, it would not have been dispensed with. There are a lot of complications associated with it. I don't think IAF will accept it.

However the proposal works well in theory otherwise.
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Re: Kaveri & aero-engine discussion

Post by chetak »

JayS wrote:
chetak wrote:
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.
Vina is proposing to use water injection only for TO and climb out. So the water tank wherever it is will be empty soon enough. (Surely during TO, there will need to be a small tweak to be needed in FCS though, but I think this should be fairly easy). Even in case someone wants to make fin a wet fin for fuel, that fuel should be consumed during idling/Taxing/TO itself. It will indeed need FCS modification otherwise. 100kg at ~5m from CG is similar to 500kG at CG.

Main challenge would be to create the water injection system in the engine and related ducting in the aircraft. Had it been a fairly simple system, it would not have been dispensed with. There are a lot of complications associated with it. I don't think IAF will accept it.

However the proposal works well in theory.
If that is all, it should be OK. Even the plumbing is fairly short and the pumps are maybe engine mounted. There would be other issues to solve. The RR Dart used water methanol injection in some variants so the IAF may already be familiar with the system in a historic sense.

The wet fin for fuel is used by the IL design bureau for sure but I cannot specifically recall now if the IL76 uses it or not.
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Re: Kaveri & aero-engine discussion

Post by jaysimha »

found these 3 papers. Posting for records.

Designing Turbine Blades for Fatigue and Creep
https://publications.drdo.gov.in/ojs/in ... /5872/3016

Fuzzy Computing for Control of Aero Gas Turbine Engines.
https://publications.drdo.gov.in/ojs/in ... /4184/2442

Software for Fuel Schedule Selection and Transient Behaviour of marine gas turbine
http://publications.drdo.gov.in/ojs/ind ... /4410/2591
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Re: Kaveri & aero-engine discussion

Post by Haridas »

pravula wrote:Cheapest antifreeze is a mix of methanol+water.
Saar, do care to read the paper, it teaches using methanol & water as a known prior art!
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Re: Kaveri & aero-engine discussion

Post by nachiket »

Doesn't water injection lead to thick black smoke due to unburnt fuel trailing from the exhaust? You can see that in old photos of 707 or B-52s where they used water injection during takeoff. I guess it is not a problem if used only during takeoff and climb, unless maybe if the airbase itself is under attack. But the IAF will consider that for sure and may object.
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Re: Kaveri & aero-engine discussion

Post by JayS »

Some interesting History
https://www.icast.org.in/news/2005/oct05/oct04db.html
While Air Vice Marshal Roy Chowdury, the founder director, initiated the project as an engine technology startup, Arun Prasad developed test facilities.

Dr R Krishnan concentrated on materials and metallurgical support, besides setting up test beds and also engine integration with the LCA, and thereafter S C Kaushal focussed on component testing and certification procedures apart from rotodynamics.
From one of the former GTRE Director R. Krishnan. Can't copy text. So click the link to read.
https://books.google.co.in/books?id=Z-M ... ng&f=false
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Re: Kaveri & aero-engine discussion

Post by pravula »

Haridas wrote:
pravula wrote:Cheapest antifreeze is a mix of methanol+water.
Saar, do care to read the paper, it teaches using methanol & water as a known prior art!
Sorry for not being clearer. I was responding to this comment from chetak, implying water+alcohol is also a type of antifreeze.
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.
prasannasimha
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Re: Kaveri & aero-engine discussion

Post by prasannasimha »

Regarding water injection incidentally Kaveri blades were modified to be liquid cooled with a channel in it when I saw it in one of the exhibitions.
ramana
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Re: Kaveri & aero-engine discussion

Post by ramana »

The idea is to inject in the burner to add mass flow.
prasannasimha
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Re: Kaveri & aero-engine discussion

Post by prasannasimha »

Yes but when I asked I think they had toyed with or implemented that idea already as they were telling about some channels for water I asked if it was just to cool and they said it was not the only reason and the subsequent discussion went over my head. When I saw this discussion it suddenly reminded me of that discussion. So they may have toyed with that idea
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