JayS wrote:You actually limit TET from going to max on ground and lower altitudes to keep thrust artificially lower than what is possible. (that means lower fuel consumption to some extent but then you are forced to use lower BPR so some disadvantage there. Its complicated enough that we cannot make generic statement. One would need parametric analysis of the engine to see overall impact). What flat rating means is that you design the engine to give 54kN thrust at say 10000ft rather than designing it for 54kN on ground. (getting same thrust on ground is easier than at altitude, so in that sense its harder to design or overdesigned). So you are overdesigning the engine so it can still give same thrust at altitude that it gives at ground. Had Kaveri been designed without flat rating it would give 54kN thrust on ground and may be say 45kN at 10000ft altitude. Now it is designed to give 54kN at 10000ft and suppressed to keep it at 54kN on ground by limiting TET, when it could perhaps give 65kN on ground by removing limiter on the TET.
There are quite a bit of benefits of flat rating which make it a very attractive preposition - your fighter has much better thrust available at altitude. You can perhaps even supercruise. You have somewhat better life for HPT components since they run at lower than max temp on ground. You could perhaps even trade off some of the saving in life to hike max TET at altitude to extract slightly higher thrust. You can definitely do stuff and it gives a significant edge to your fighter. But then it also makes you work hard.
Do read the paper linked by Jaysimha above - it explains Flat rating concept used in Kaveri.
Yes. Yes. That paper posted really helped clear some of the misconceptions I had as well, the way GTRE has gone about it is different from how flat rating is usually done.
But that said, all this is Chai Biskoot . Bottomline. Do you have a solution ?
Believe me, there is a solution that will "liberate" the full performance of the Kaveri at SLS (Sea level Static) conditions (the Kaveri is a LARGE engine 78kg/s mass flow rate vs the others like GE 404 and M88 etc) where it has been throttled.
I actually emailed the DefExpo 2018 folks the following early last week.
Is there some way to include a topic in addition to the ones listed in the “Open Challenge Competition - Solution to Problem” DefExpo 2018 ?
The Kaveri Turbojet engine program for the Tejas fighter aircraft has not resulted in a useable product despite the best efforts over nearly 30 years and nearly Rs 2200 crores being spent on it. Though the Kaveri engine (from the DRDO published information) has been successfully flight tested in Russia, it is still not generate sufficient thrust to meet the requirements of the Tejas Fighter with the result being that Tejas flies with an imported
GE-F404-IN-20 series engine. The later versions of the Tejas ie (Mark 1A and Mark 2) too seem destined to have foreign engines.
You will agree that having our own domestic engine that can successfully meet all the current and growth requirements of the Tejas Fighter and future follow on programs that are proposed like the AMCA , will have a huge bearing on national security, and is strategically vital to insulating our national capabilities from any possible coercive sanction and denial regimes that they have been historically subject to.
I have a very easily implementable and well proven solution that will allow the existing Kaveri engine to fully satisfy the current and future growth requirements of the Tejas program and can with modifications and enhancement address the powering requirements of follow on programs such as the AMCA as well.
I would be much obliged if you could include an additional topic namely “ Enhancing The Thrust of an existing Flat Rated Turbojet Engine” in the “Open Challenge Competition” in the DefExpo 2018. Doing so would allow me to submit a possible solution to be considered for a strategically and economically vital national program which while nearly there in terms of a functioning engine, has not been able to cross the finish line in terms of thrust required.
Obviously, knowing how things work, I
DONT expect to hear back from the DefExpo folks. But thats okay. I will send it across to a couple of folks who will possibly able to pass it on the right folks to look into it.
