Power Turbine Locked

For an air seal test of an LM2500, we lock the output shaft of the intergral power turbine so it can't move.
First run we did not even get to idle before the unloaded and unlocked PT started to approach its full running speed.
We shut the engine down, and Byron built a locking fixture for the output shaft of the PT. Then we ran the engine to idle, and just above that to check VSV activation threshold.
Everything goes great.
The VSV tuning is bang on, and the air seal flow is in the range of what we want to see.
I didn't get much footage because I was on fuel purge and hookup duty, and I only had one camera.

[@AgentJayZ]

That is exactly our difficulty here: no load for the PT. So we fixed it in place. Where I used to work, in order to test a 50MW LM6000, there was an agreement with a local power station where it would temporarily be installed on one of their generators, and feed the power generated into the grid, which has a limitless, insatiable demand for electricity.

[@AgentJayZ]

The 1500 part indicates power. Originally the LM1500 was nominally rated to provide 15,000 Hp, and the LM2500 was originally rated at 25,000. Nowadays, the LM2500 puts out a reliable 35,000 Hp, so you have to let the clutch out real smooth.

[@DanBowkley]

Wouldn't need or want a clutch...just a reeeeeeeeeeally beefy reduction gear and the mother of all rear ends. Any chance you've had a good look at the redux boxes on a navy ship? Man they're beastly. We had two LM2500s driving a single screw, I think it'd run like 250 RPM at 2.1M lb*ft. Stupid torque outta that thing.

[@Sadik15B]

Doest it makes sense to fix the stators at max power setting since it wil always run at full power??

[@jaik195701]

S Bayko just speculating but maybe a risk of compressor stall during start and run-up or excessive turbine inlet temp at low RPM?

[@clayz1]

S Bayko My question too. I think using variable stators is what AJZ means by letting the clutch out smoothly?

[@lewiemcneely9143]

UNreal, and yes, I can EASILY see an unloaded power turbine going through the roof, and sides and parts bouncing off the floor from overspeed. Thanks Jay! A-PLUS!

[@Iflyagrasshopper]

I wonder what George Bailey Brayton would think if he saw this...? It's amazing that this engine cycle is over 200 years old. first proposed by Barber in 1792. Brayton produced his piston "Ready Motor" in the early 1870's. A Brayton cycle engine also powered the first submarine "Finian Ram" in 1872... and the first internal combustion car Selden in 1877.... There are very few running examples of the piston version of the Brayton cycle and most folks don't realize it started as a piston engine. Thanks for making these videos.

[@juang8549]

Seeing and hearing an LM 2500 engine run again brings me back to my GSM days on my first Navy ship USS Nicholson. About 60 secs to self-sustaining speed at least for marine applications. Thanks for the vid.

[@mauriceupton1474]

G'day from New Zealand, the peaking load Power station next to us uses these LMs as its power source, refurbed at Air- NZ work shops.

[@htx4941]

Been learning the assembly and disassembly of a GE-10 1 and 2. Looking forward to learning how to assemble and dissemble these guys !

[@snaproll94e]

What I appreciate most about your work is these powerful machines were hand built and it takes skilled technicians to get them right, the first time!

[@dhampex]

Professional fixture for that stationary turbine,, he did a good job making that fixture.

[@AgentJayZ]

This is an industrial engine used to make electricity. Large tanks of deionized water are on site. Aircraft that once used water injection would typically only carry enough in onboard tanks for a max power takeoff. The F-105s in Viet Nam had the J75-P19-W engine, and would carry 75 gallons of distilled water. After a fully loaded takeoff using afterburner and water injection, the water would be gone, and they were looking for a tanker ASAP. Min fuel, max ordinance load.

[@AgentJayZ]

It's deionized to prevent deposit buildup, and all of the parts in the gas path are either titanium, stainless steel, or high-nickel refractory alloy. Corrosion does happen, but extremely slowly.

[@AgentJayZ]

Only smaller engines, usually for helicopters have bladed disks. Your are right about bleed air. Air can be taken from any stage on the compressor, and could be called bleed air, anywhere from 200 to 800 degreesF. But what is most commonly referred to as customer bleed air is usually tapped off from the forward half of the compressor, where pressures and temps are moderate. Customer bleed air is used by the aircraft. Other stage bleeds are used by the engine for various purposes.

[@AgentJayZ]

Gas path not restricted. Starting hiccups are not unusual, and this one was very small. PT makes 66,000lbs-ft of torque at full engine power. At idle, probably not very much at all. Power curve on the GG is very low until rapidly increasing during the last few hundred RPM. We were at 4800 rpm. Max GG rpm is 9200.

[@AgentJayZ]

The turbine engine is limited by temperature, so no matter what fuel is used, the same temperature is reached. The CF6 has higher compression than the old jets, but lower than the more modern ones. Some airliner engines run at over 40 bar compression.

[@meowpyao5552]

Subscribed, i'm a young tm2500+ gas turbine operator still learning and this videos would be good reference. Two thumbs up

[@42Goatee]

...there was a time when I was worried about how many evenings I spen, alone, watching your videos...I thought maybe I was wierd or socialy degenerate in some way but I have realised that I am not, I am not alone...there is you, you make these videos and I am far from the only person who watches them so that must mean that far from being weird, I belong to an exclusive, minority elite...this thought is an enormous comfort to an old man...

[@AgentJayZ]

Welcome to Jet City!

[@EADO_HTX]

Nice video I work for GE Water and Power in Houston and we overhaul these lm2500, lm600, and lms100

[@AgentJayZ]

The fan on a CF6 turbofan engine is using all the power produced by the LP turbine. If we remove the fan, and use the power produced by the LP turbine to drive a different load.... then we have the LM2500, and we call the LP turbine a Power Turbine.

[@AgentJayZ]

The books call it compressor ratio, I think mainly because piston engines have a static compression ratio, and static compression of an axial compressor is zero. The LM2500 does use more fuel than the LM1500, but not double, because it is a bit more efficient, due to it's better sealing and higher compression.

[@AgentJayZ]

That's just a minor detail of this video, and I probably should not have even included it in the final edit. Everything I know about water injection is presented here. So it's unlikely I'll talk about it again.

[@AgentJayZ]

Fuel controls are very responsive. Fuel is delivered based on PT load. If the load is lost, and fuel is cut, the PT can not overspeed.

[@AgentJayZ]

That's quite a leading, almost trolling question... It's a major feature of the design, and a breakthrough in the history of gas turbine engine development. For the best answer to this question, I always recommend either "Aircraft Gas Turbine Powerplants" by Jeppesen, or "the Jet Engine" by Rolls Royce...

[@AgentJayZ]

Usually the engine (technically gas generator) provides a supply of hot, moderately pressurised (30psi) exhaust gases, via a straight duct, to a power turbine which turns that energy into torque. We can replace the PT with a restrictive cone which is actually smaller than what would be on the same core to make it an aircraft jet engine. We have tested LM2500s with such a cone, and I have posted videos.

[@OneRoundDown]

Wow great video. Brought back memories of fabricating and welding all those tubes for the HPT/LPT cooling air. Worked for GE Aviation Unison. I enjoy your videos and the engine tests. Thanks!

[@AgentJayZ]

It seems, from all the different ways I've seen it done, that water just needs to be sprayed in. I've seen nozzles spraying water directly in with the fuel, or spraying water into compressor discharge, or into the inlet of the entire engine, or even into the mixing air, downstream of the combustor flame zone. The advantages and disadvantages of all these different schemes I do not know about.

[@AgentJayZ]

The owners of this LM2500 have developed their own 2-stage water injection system, intended mainly to reduce NOx emissions due to the lower firing temperature. Contrary to all the explanations put forth below.

[@AgentJayZ]

No, as I explained before, rain is not a significant source of water for these engines. This engine consumes several gallons per minute of water during augmented running.

[@AgentJayZ]

We don't deal with commercial airliner engines, but they have very strict requirements for maintenance and inspection. What you are describing is "on condition" maintenance, where everything is inspected at specified intervals, evaluated then,and repaired or replaced as necessary. That's how it's done with industrial engines, and cost is always a factor in these decisions. Airliner engines have many parts that must be replaced regardless of conditon a specific intervals.

[@AgentJayZ]

To someone used to servicing industrial engines, the maintenance of airliner engines is focussing solely on reliablity of the engine, regardless of cost. Operation and maintenance of an industrial version of the same engine that also powers an airliner would cost about one tenth of what it cost for the aviation engine. Good to know, though, when you look out over that wing, and realize the blades are red hot in that fifty thousand Hp beast lifting it into the sky.

[@dwizzleusa4202]

Yea the lm2500 is a beautiful turbine engine!!

[@AgentJayZ]

For all practical purposes. No detectable leakage is allowed, but I'm sure the odd stray molecule fights its way through.

[@AgentJayZ]

Whether the PT is moving or not doesn't change the conditions under which the engine operates. A large load is the normal situation for the PT. When the load exceeds the torque available from the PT, I would try not to describe it as a stall, only because of the use of that word in the aerodynamic sense. There was more gas velocity than I expected in the exhaust, but it was not as much as a jet engine, with a proper, gas-accelerating nozzle.

[@AgentJayZ]

The engine oil pump supplies oil to the PT bearings, so they are fine.

[@tafgull53]

Very Good film worked on LM 2500 + & TM 2500 good engine and easy to work with also good power package thanks for sharing

[@64jorthom]

FANTASTIC VIDEO!!! I am missing those beautiful winters day! Don't tell anybody. I love your videos, all of them!

[@AgentJayZ]

No comment on any airliners. This video shows us shutting down the 2500 before even reaching idle power, and then building a PT brake to continue testing. Roof is OK!

[@AgentJayZ]

Yes, and it was added to quite a bit.

[@AgentJayZ]

Thirty Five thousand horsepower is the nominal output. I have roughly convertedthat to 40MW. Give or take. An arrangement like the one you suggest would require a generator, electrical heaters, fans, all the wiring, and the installation process, which could take months. All at a reasonable cost of.. just guessing... half a million dollars. All for a 20 minute test of an engine we deal with about once a year. I think Byron's 2 days for making the brace is a better deal.

[@AgentJayZ]

The fuel nozzles spray fuel directly into the combustor. That's why it's called a combustor. This engine has a single annular combustor.

[@kitingboarding]

The figures always amaze me. A 35,000 Hp reciprocating engine would be the size of you're test cell...... well, almost. Oh, and 25:1 compression. Again, amazing!

[@BlitzvogelMobius]

Expansion of water into steam at high temperature in the combustion process adds quite a bit of mass to the flow, producing more thrust, but helps to reduce the temperature a bit as the mass flows into the turbines. You need quite a bit of water though, and it's volume that otherwise could be taken up by more fuel. The Rolls Royce Pegasus in the Harrier for example has water injection for max thrust during VTOL operations to keep the turbine inlet temperature manageable while adding thrust.

[@deSloleye]

Cool to see the PT. I was wondering about the effect this has on the engine. Does having it stationary change the load on the engine compared to when it's allowed to spin? If a large load is applied to the PT, does the mass airflow (and thus core RPM) reduce? Is there a such a state of PT "stall" where there's too much load and the PT RPM is too low for it to efficiently extract power. I noticed not much snow was blown away. Is there much residual thrust coming out the back of the PT?

[@bagelboi66]

Hint: Jay's shop is currently rebuilding the only privately-owned surviving example of the priceless and historic Orenda Iroquois engine. When he puts up the video of that engine lighting off in their test cell, we'll all have earth shattering eargasms.

[@deathk26]

Since the stator blades don't spin with the rest of the engine they don't experience any centrifugal force. The rotor blades do spin very fast and experience a massive amount of centrifugal force, which is why they are slightly loose in order to avoid those resonances that can cause damage.

[@zdenekstryhal9136]

Thank you for for reply. I knew that at starting rpm the pressure is lower than at full rate, I'm surprised how low it actually is. Thanks for education you do.

[@BlitzvogelMobius]

The Harrier carries 500 lbs (50 Imperial Gallons) of distilled water, of which during max thrust it consumes 35 imperial gallons a minute. That's about 90 seconds worth. Depending on time constraints and water injection, between 14,450 lbf (64.3 kN) (max. continuous at 91% RPM) and 21,550 lbf (95.9 kN) (15 s wet at 107% RPM) of lift is available at sea level (including splay loss at 90°) -Wikipedia

[@343jonny]

Jay. Just wanted to kindly let you know that you are right when you say that the pressure ratio can also be defined by the volume ratio (just inverted). This relation is from Boyle's Law. I always enjoy seeing how sparkly clean and shiny all of the parts on your engines are. Is this because S&S cleans them or because the parts are new? Also curious as to why they doesn't use or at least have a link to your videos on the website. Customers would appreciate your dedication.

[@artestuninngbrasil728]

Videos lancede in 2016 its sou moment encontral o mi God... qant time fara. Mi drins is mecanic e rapar aviacaõ. Tenk you guys Is diz BRASILIAN. LOVE IS BISSNES MECANICO.

[@rk81oman]

Very impressive to see an engine with a power turbine. Another "secret" revealed and many questions answered :) And another appearance of the lasercut-decal :) Very nice on the LM2500! I have one question about the one-way clutch in the starter... Is the clutch "rattling" when the engine is running? Or does the starter turn with the engine?

[@AgentJayZ]

We think it means Land and Marine, but you might want to check with GE just to make sure.

[@oisiaa]

JayZ, you should change your title to include the words "Water Injection". There isn't much information on water injection on KZbin. Actually, now that I think of it.You should just do an entire video on water injection. The old J57 engines on the KC-135 used water injection for takeoff.

[@AgentJayZ]

At Idle? very little. The fixture was built to resist torque. I would bet it could safely hold 10,000 ft-lbs all day long. It's made of half-inch steel plate. The PT produces over 60,000 ft-lbs of torque in normal operation at 100% rpm. But at idle I would bet it's less than 500.

[@343jonny]

I can't say from experience with gas turbines (that is Jay's domain), but we have done lab tests on steam turbines and use thermocouples to read the turbine inlet and outlet temps. There is certainly a drop in temperature across the power turbine and this is also confirmed by The Jet Engine by Rolls pg. 15. So, as far as I know (open to correction) the EGT w/out a PT would be higher, but, like Jay said, it would be pointless to use the LM2500 as a space heater to warm the room in the winter.

[@jscussel]

Sweet video. Can you discuss more about water injection sometime? Things like what happens if too much or too little water is injected and so on are questions that I have. Indeed, looks like a nice day to be working outside.

[@teenflon]

Bit late to the video, but enjoyed watching it. The water injection is interesting, i wonder if it’s to increase the overall mass of the air flow going through the engine to increase thrust, if its jet fuel run there will be a lot of mass added to the air flow whereas running on propane won’t add much mass. Would be interested to learn more!

[@AgentJayZ]

Water injection is used by this engine to reduce NOx production.

[@DiveTunes]

Awesome videos, thanks! Maybe you have covered this, but what is the shut-down procedure? Do you just cut the fuel off, or ramp down throttle on a schedule for cooling?

[@kieranhimself3655]

Run synch idle for 15 mins then good to stop

[@AgentJayZ]

The manufacturer (GE) recommends idling for five minutes before shutting off the fuel. In an emergency, cutting off the fuel at full power is not a big deal, but does put a bit more stress on the hot parts.

[@AgentJayZ]

that is not bleed air. It is seal leakage vent air. it is of much smaller quantity of flow than bleed air.

[@DScottDuncan]

Great to see a P.T. in action. Thanks again! Darren

[@AgentJayZ]

No. The effectiveness of a compressor increases with speed. At starting rpm the compressor discharge pressure would maybe be 5 to 10 psi. At full rated rpm it may be 600 psi. That is one reason it isn't called a compression ratio. It's best not to try and apply piston engine understanding to gas turbine engines.

[@ryannakamura1913]

I like the modifications of the gearbox assembly especially the starter. Looks like the starter has the same bolt pattern and no lock wiring involved. I remembered using the jacking tool to disengage the gears inside the gearbox before you dismantling the starter. It was a b----h taking the thing out laying your back! But Iv'e done a lot of change outs/maintenance according to the PMS. lol....memories.

[@soto74945]

Ryan Nakamura q

[@james_orange]

The best channel in KZbin in my opinion :) I was a aerospace engineering university student , but now I am studying to be an AME :) can I add you in Facebook, Agent ?

[@AgentJayZ]

+Thiago Laranja I don't spend any time in Facebook, but I do have an account.

[@james_orange]

+AgentJayZ haha, I got it , me too :) so, in this case , is there another way to keep contact with you ? (If you want, of course haha)

[@Avilator189]

If I may step in for Jay (hope you don't mind!): Most (AFAIK) modern gas turbines in aviation applications do not run water injection. I have yet to read/hear about a modern aircraft with water injection, be it a fan or shaft engine.

[@TeemarkConvair]

wow,, i didnt notice the date, just thought that J sure cleaned up well,, LOL

[@supersavage123]

hi agent jz awesome vid as always, i noticed the engine backfired a little on start with the locked PT, was that dew to restricted exhaust gas path also must be a strong brace to hold a pt driven by 30,000hp :P not sure if you know but whats the torque curve on an PT like this cheers

[@1stMjolnirMarkV]

10:30-10:40 I about lost my mind when you walked in front of the inlet.

[@AgentJayZ]

I think I mention where I work in almost every video, and on my channel.

[@AgentJayZ]

We aren't... GE did that when they designed the LM2500. We just fix the thing.

[@cck1496]

Excellent work. It's too late to ask this question 1) What is that hose for that you were tightening? 2) What are those orange/red colour pipes? 3) What were you checking with the paper by placing it at a duct? What is that duct for? Thanks for sparing your valuable time.

[@AgentJayZ]

Without a time reference to your question, I have to review the entire video to figure out what you are asking about. Yeah, no.

[@erikelhammer]

Nice vid, Jay! Got a question for you: Do aviation water injection systems have a layout similar to the lm2500 setup, or are there separate injectors for water that bypass the fuel nozzles and run directly into the combustor cans?

[@AgentJayZ]

No, I have not worked on that classic hot-rod of an engine.

[@rk81oman]

Sorry, i just noticed there is the Video "Questions 08"! You are releasing incredibly fast :)

[@karlbuttler]

HI AgentJay, Glad I found your channel, I should learn a lot.. Is that one way clutch called a sprag? So I guess the 100psi was oil pressure?

[@clockman47]

Thanks Jay.

[@bduym69]

know you have mentioned it a couple times. and i have just ran threw couple of random videos and couldnt find it. more interested in which area(geographic location) in which you work. and how you like it and all.

[@raymondnicholson1492]

What an amazing soud

[@rapsod1911]

I have question for next "your questions" segment: if blades of compressor are not fixed in order to avoid breakage due to resonance, why are stator blades fixed? Is bearing in power turbine same as central bearing? Does it use separate oil pump?

[@TheBodvarg]

try using a heating core and watercool them like we do here for diesel generator testing

[@PaulHigginbothamSr]

I got a commanders ride too, at el toro, to fly the f18 flight simulator, big jobbie.

[@robinnoteboom]

Injecting methanol-water will lower the temperature, thereby air can contain more moisture and increase weight. This extra weight causes the thrust to rise. Keep F=M x A in mind!

[@BorosTheGamer5021]

LOL my brain hurts whenever i watch a video of you explaining how a jet engine works.

[@AgentJayZ]

Travis Brown That's completely normal! You are thinker than you smart you are!

[@alanheli2459]

Thanks for all your videos it helps for school

[@erikelhammer]

Thank you for the info. I figured that was the case. I am still quite curious about the old setups you might find on turbojet 707s, B52s, etc. If you or anybody else knows, please do enlighten me.

[@Hercules718]

Thank you for this.

[@douro20]

They could put a water brake on it, but a water brake for 20-30MW would be almost as big as the test cell itself.

[@grahamj9101]

douro20 Not quite, but the water brake used for the Marine Olympus 'shore trials' installation was certainly a big machine. And, if you think of a 20 to 30MW alternator as a dynamometer, then that is a sizeable machine too.

[@cmsracing]

Love the way you explain things! How does injecting water increase HP, will this work on other types of internal combustionion engines?

[@AgentJayZ]

cmsracing Far too large a question to be answered in a comment box.

[@cmsracing]

AgentJayZ I now understand the cooling effects, but what I am wondering about NOW is the oxygen and hydrogen being released have more effect than realized?

[@AgentJayZ]

Water injection causes the water to heat up and become steam. It does not cause disassociation into hydrogen and oxygen. Anyone who tells you that it does is a dreamer and insufficiently educated.

[@cmsracing]

AgentJayZ Thank you!

[@lekoman]

"Yeah, sure, but is it a Hemi?" that Ram out front asks, pouting... ;)

[@robertmencl9169]

wow you get a lot of comments! I have an old Iskra TS-11 and am looking for a J60/J12 to swap in. they were used in Sabreliners etc. Please let me know if you see one for sale. thanks, Robert

[@jimmysparks315]

I understand water injection on ICE engines... Is W.I. done for the same reason ?... Is the water constantly injected 24/7 ?..... I'm guess you can more power because you can run it 'hotter' ?

[@Heathfx5]

it would be interesting to have load cells on your power turbine locking fixture to see what the locked rotor torque is.

[@fuzzy1dk]

at the rated speed of 3600rpm and 25000kW = ~66000Nm, I might be wrong but I believe a power turbines torque goes up with decreasing speed, so it'll be more than that

[@micstonemic696stone]

I so wish this is a reasonable question Is it possible to attempt a gas-turbine start-up, if fuel is introduced at a airflow is to high FADEC aside but purely manual but N1 13 - 15 % but if starter goes beyond 20 + % without fuel until these High levels is positive self sustaining start possible I really hope this isn't a dumb question !, I just wish to clear this up, does the starter stabilise, but then I wonder about jet start-carts 4in pipe and 25psi ? you are welcome to share with class if deserved

[@whamalek]

Great video as usual! love your videos AgentJayZ, one question, how does the engine run while the turbine is locked? aren't they connected?

[@AgentJayZ]

+Waleed ALmalik You need to be more specific. This engine has two turbines. One powers the compressor, and is turning. The other is a power turbine, which is locked in this test. Have a look at a video I have up called turbojet vs turbofan, or something like that.

[@whamalek]

AgentJayZ I'm confused, the engine runs to turn the power turbine right? so the power turbine will turn because the engine is turning it, now the power turbine is locked! I'm mean it doesn't turn right? isn't it connected to the engine output shaft? how it can be locked? or I'm just confused :-) sorry for the bad question.

[@whamalek]

AgentJayZ Watching 'your questions 33' explain it for me. thank you.

[@mhmedbadra1986]

@Waleed A.Malek two turbine means ( Gas generator turbine & power turbine . The power turbine is specifically connected to for example Ac alternator or gearbox to propeller in marine gas turbine.

[@edwardarruda7215]

I was in the air force and worked on J57 with water injection, very noisy.

[@lekoman]

Solely as a space heater, you might as well just burn the fuel without putting any turbines in the way. But if you're generating electricity anyway, there're Combined Heat & Power (CHP) systems that recapture the exhaust heat from power-generating gas turbines to help heat structures in cold climates. Efficiency anywhere they can find it, fuel prices being what they are.

[@olavipasanen4471]

What does a normal maintenance/bigger shut include? Do the airlines change a certain set of worn parts reaching deadlines of operating hours and what are they? What is the major area in jet engines demanding maintenance? Or do the jet engines need much tracking, service, overhaul?

[@AgentJayZ]

Didn't I answer that in Questions 08 ?

[@udayangaunawatuna]

sir can u explain what is the surge in the turbine engine.. and it s sound.. thank u for ur all videos.

[@MrMeganolife]

Did the device on the back of the PT start out as a fixture used to store and ship the engine?

[@JFKgoodfren]

Compressor Pressure Ratio is correct i think. there is also Burner Pressure Ratio

[@conoba]

I wish I had yacht with that thing in it.

[@AgentJayZ]

+MainsOnTheOhmsRange Quite a few cruise ships use them.

[@sc0tte1-416]

I was wondering how these were able to be connected to a generator, thanks! What type of turbine did they use to use in locomotives?

[@AgentJayZ]

sc0tte1 That's what I try to explain with this video...

[@sc0tte1-416]

AgentJayZ I know, I was saying thanks because now I understand lol :P