Twin Shaft Turbine Engine Bearings
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- เผยแพร่เมื่อ 2 ต.ค. 2024
- Bearing types and locations in a modern twin spool turbofan engine are examined in the shop, test cell, and on the whiteboard. This is a response to a question from a viewer, so send your ideas in...
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I would like to say (Thank You) for all your time and effort to bring this amazing series for all of us to learn from.
Thanks man.
I have watched about 5 of your videos tonight and have learnt a lot of things that I have been curoius about for many years.
Much appreciated.
A turbine disk is extremely heavily built and is turning at a very high rate of revolution. In the extremely unlikely event that it should fail, nothing can stop the released energy and nothing can protect against the flying pieces of metal debris.
The good news is that, if this one-in-ten-million chance event happens, the pieces fly out in the plane of rotation of the turbine. The lines indicate this plane, and you are advised to stand out of it.
as you said that those videos are all nice and cool but no complex details like this one. Thank you
Always wondered about the bearing arrangement on twin shaft machines! Thanks for this
I could not be more pleased with this video. Thanks
For all you curious cats out there, I'll save you some math, (technically, arithmetic).
There are 614 HP compressor blades * 15 minutes = 9210 minutes, or 153.5 hours, or 6 days and 9.5 hours.
Just to inspect the HP compressor blades.
What's that, you want breaks, we don't get no stinking breaks.
Another excelent vid Jay. Since ive been watching your vids, i see engine parts as props in sci-fi movies all the time now. e.g. STAR WARS a new hope: Centrifugal engine type intake screen in background of Luke's Tatooine house, ? a combuster can on shelf, stator section on the ground outside Mos Eisley cantina, double sided centrifugal compressor disk and and compressor manifold atttached to one of the manned cannons on the death star during the end battle scene. Keep up the good work.
Although not really the kind of engine you encounter, I'm curious if you have any comments to make about 3 spool turbofans and especially in the light of the competition from the increasingly popular geared fanjet.
@MonoBawuino Dude... have some respect for the old school...
The JT8-D is the most-produced large turbine engine in history. The CFM56 is a fantastic, beautiful, efficient and wonderful machine, but it dreams in its wet dreams of ever being as successful as P&W's transitional masterpiece.
So now that all these parts come together, is there a real-world simulation to see how each compressor stage acts on the air? e.g. by using different coloured air pass through the engine or something along those lines?
@mwiz100 Hey, I'm a Canadian, and proud of what my fellow Canadians have done...
@daniel2001 You could think of the HP system as the essential engine, or the "core" engine... and that's what it is sometimes called. The LP system is mainly a way of harnessing the power of the HP system and using it more efficiently to propel the aircraft, and it also acts like a supercharger for the HP "core".
All of the accessories and power take-off devices take there power from the HP system.
The only thing running off the LP system is the LP speed sensor.
hey Mr.A.JayZ....that was a fantastic video.....I would like to knw whether CFM56-7B is having the same sets of ball n roller bearing in it??
There seems to be significant variations on the placement location and configuration of the bearings in multi shaft turbofan engines depending upon which engine. Thank you for motivating me to go down that rabbit hole.
great shows sir,i love to watch your great presentations, Thank you very much for sharing the knowledge with us
Beautiful video of exactly the details I wanted to know about. Thanks for making it.
Yes... it seems hard to believe at first, but the LP system is never in any way mechanically driven by anything. The exhaust of the core has a lot of energy left in it, and could be accelerated out of a jet nozzle as it would be in a turbojet, or it could drive an LP turbine, which turns a huge fan and a compressor which feeds the core. The second option is more efficient, and quieter, which is why all big airliner engines are turbofans like the CFM56.
Spey has two shafts or systems. HP system and LP system. The Trent is based on the earlier RB211, which was The first three-shaft engine successfully introduced by Rolls Royce. HP, IP, and LP systems.
The Orenda 14 will be tested soon, I hope. We have many projects on the go...
A couple years ago I posted a video of an Orenda 14 with elctric starting. "It's called vintage fighter jet engine".
I've also got videos of electric start RR Avons...
...and propane burning Orendas...
The F-18 and the F-16 have different engines, but both are low bypass turbofans, which makes them twin spool.
The type of turbojet which makes the most thrust is the one that flows the most air, and that usually means the biggest one, all things being equal, and they aren't equal.
Afterburners add thrust to a turbojet, and not all of them have them.
@AKiss620 cosistency is a big factor. Many small changes are added to newer editions of the manuals and documentation. A change in naming of parts that would contradict versions of the books would be awkward, expensive, and is generally avoided at all costs.
@tvirus457 ... If I said it that way, it's wrong. The radial drive shaft would be driven by the HPC, and the most sensible place to do that would be from one end of it, and the cold end would be better than the hot end.
Your location is the right one.
But how many Bacon Strips does a CFM56 have?? LOL
@343jonny It's not really vacuum packed, but it's packed in oil to prevent corrosion. The packaging is sealed to prevent leakage, and looks vacuum packed to use as little oil as possible.
This nearly incoherent question is I think asking if there could be enough axial movement of the shaft due to heat expansion for the blades to come in contact with the vanes.
Remember the engine cases are heated and expand also.
But no, the engine is designed with clearances greater than the axial movement would be.
@matube73 Also in Star Trek 2009, at about 1:25:00 there, in the engine room of the Enterprise, is a J79 afterburner fuel manifold ring, an LM2500 compressor case, and a stack of J47 combustor cans.
Cool that we work on all of those engines !
And in the pilot episode of Battlestar Galactica (2003 ?) in the maintenance bay there are several RR/Allison 250 turboshafts on rolling stands... That was shot in the old BCIT building where I trained on those exact engines.
12:00 Sorry but the Airbus A330 doesn't use the CFM-56 (that would be hilarious to see 😂).
They use either the GE CF-6, RR Trent 700 or the P&W 4000.
Yeah...I must have had the 340 stuck in my mind. Apologies!
Common error: The KC-135 series is a close derivative of the Boeing 369-80 technology demo aircraft. I beleive the wing is closer to the B-47 wing though I am not sure The 707 has a wider and longer fusealage and has a different wing though the two aircraft do share many parts and of course look similar. The 707 is 25% heavier.
Thank you! I can't beleive I got all the way through propulsion 1 without ever considering, mechanically, how X amount of thrust got transferred from the front fan to the airframe. Also seeing the way the shafts were braced was really enlightening, I need to take machine design and get a look a that stuff analytically
Some engines use variable stators and others use compressor bleed valves to limit the airflow through the compressor at low rpms to avoid a stall.
Aerodynamic refinements and advances in materials, as well as inlet design has helped a bit over the years, but turbofans are much quieter than turbojets because the exhaust is expelled at a much lower velocity. What makes them more efficient also makes them quieter.
Both turn the same way in this engine. The axial force on each shaft is the sum of the compressor pulling it forward minus the turbine pulling it backward.
These values vary with aircraft speed, engine rpm, and fuel flow to the combustor.
Often these engines have a "balance chamber" which is a cavity behind the compressor last stage disk fed with compressor discharge air to push the whole rotor assembly forward, balancing against the rearward pull of the turbine.
I'm not the expert on that subject but I hope he chimes in. I know the aerodynamic shape of the compressor blades, turbine and turbine nozzles were changed.
The TF41 was tougher, simpler, and more powerful. Still, a very intricate engine with superior fuel economy for the power it produced.
@crazyrum Ball bearings by their basic shape can handle axial loads in either direction. Thrust bearings are slightly modified, as shown in the video, to optimize their load carrying in one axial direction, but they still can handle both.
The load on the thrust bearing in a gas turbine engine changes in magnitude with power output, but it is always in the same direction.
@crazyrum The turbines are connected to the compressors. Typically for each shaft there needs to be three bearings: supporting radial loads at the front and rear, and one supporting the axial loads somewhere else.
The thrust bearing can be anywhere along the length of the shaft, as shown here by both of them being at the front of their shaft.
The blade count differs in the CFM-56s. The -2B, as used in the 135 fleet, have 44 fan blades. The more modern versions of the 56s usually have the nifty wide-chord blades that lead to a larger dia. fan with less blades that turn slower to meet the required standards for noise regs to allow carriers to fly into more airports.
I was curious if you could at some point do a video about airflow regulation in engines? VSVs/VBVs vs RCVVs, CIVVs and a bleed strap, etc. Thanks! Love the videos!
I don't know what enough of those last words mean, and thats good enough reason for me to want a video on all of that
The actual specifics of bearing locations are different for each engine, and are in the manual.
Also, you have made the mistake of thinking the thrust bearings are called that because they transmit engine thrust to the airframe. This is not so.
They are called thrust bearings because they handle axial loads, or thrust, place on the shaft. They could be called "axial positioning bearings".
There is one on each rotating shaft, and can be anywhere along its length.
@viperdriver82 You're right! I couldn't reshoot the video, and I forgot to fix that mistake with annotations. I was wondering when I would be caught.
The reason I messed up : because the 330 is one of my favorite airliners.
It looks like it giant bird that sticks its neck out far forward because it is so happy to fly.
The CFM56 needs to have the fuel burning "core" brought up to starting speed. That's the HP compressor and turbine.
So, like our Olympus twin-shaft turbojet, the starter is connected to the HP shaft.
The Olympus uses a hydraulic motor for starter power, the LM1500 an air turbine, and some other engines use electric motors attached to the starter drive.
I'm not sure what is the power source for the CFM56.
... Thanks... but why does your username contain "xenocide"... the killing of those not like you...? That's not very Canadian, sir...
I am glad you like my videos, and I feel lucky to be able to bring this stuff to everybody else. I'll keep doing it as long as I keep hearing from people like you who like to watch it !
Cheers!
Real world simulation... Using different coloured air....
Oh, yeah ! We got that... but it's an extra 10 bucks an eighth... :)
@MonoBawuino The CFM56 is getting on 35 years old or so, and still a fully modern engine. It will be very interesting to see what the next step will be.
I am 50 and I love engines. I was interested in how the bearings worked because of the high RPM's a engine runs at. they must use a lot of oil pressure? I work at a airport ( not on planes ). Great speaker . Thanks Gary
Thank u sir for your time and effort
the CFM56 is not on the A330........its on the A320 series and the early A340s
Hi. I built the first test rig for testing the intershaft bearing they drilled a little hole in the cage for a radioactive pellet sothey could measure the speed of the cage. that was back in the 1960's it was for the Phantom fighter.
For the Spey...
RR likes to do things in the most complicated way.
It's more elegant, the boffins would say!
More straightforward, they are... The engines designed in the USA!
Greetings from Canada, eh!
In the afternoon of the eve of what will soon be New Years Day!
@@AgentJayZ Hi again I spent many-many hours testing on the engine parts although I spent a lot of them on the bearings & the turbine oil rotted my fingers .
Great video explaining the two spool engine. I do have a question though. On 757 and the old L-1011 aircraft equipped with Rolls Royce RB-211 engines the engine instruments have an N3 indication. Does that mean the RB-211 is a 3 spool engine? If so what is the purpose of the third spool?
Short answer: yes.
Long answer to be in video form. Stay tuned.
I love these videos, but I cannot truly believe that that Lm 1500 bearing cost $20,000 with four zeros. I can buy a used Allison 250 for that.
@TheEPITROCHOID
... They didn't have an epitrochoid bacon strips one...
Bacon weave = win !
Cool. Who makes the bearings? SKF? what rating terms do they use for jet engines, is that always custom or do they call it abec 11 or something.
Your stuff is fantastic! Thanks so much, I am impressed with your detail and well edited videos. All I can say is thank you.
Hi Sir... It's Muthu frm India... Can you tell the difference between rotor disk n rotor hub. Also pls explain difference between disk and drum...
Thanks a lot... Keep sharing good work.
I read it. And I think it's the only place I've seen the word used.
Couple of questions about the thermal expansion.... The travel that bearing seem to have is quite massive, do you know how much of it is actually used ? If not what alloy is the shaft made out of and/or its thermal expansion coefficient ?
What type of engines does a. Dc10 and a MD11 use how much rpm do they spin at. Warm up and take off
Google Fu
I would love to see a CFM-56 Engine here
Me too!
great video Jay.
what are the exact metal types used in a turbine what are the properties and why, what types of sensor do dou find on a turbine and how is the running regulated
+Peter WRight That's three questions, each requiring a chapter in a book to answer adequately. Each of the books I have recommended in this playlist is an excellent example of just such a book you might find enjoyable to read.
+AgentJayZ once again thanks a million for what you do
20k for a bearing hu? Thats starting to sound like my job, everything overpriced. I discovered one of our foot long liquid oxygen hoses costs $500, and it was not even insulated! BTW, like the shirt, marines love epic meal time, insane amounts of food....and JACK DANIEL'S, im a sigle barrel select drinker myself. Gotta go for the EXTRA good stuff. :)
Uh, very few "ball bearings" are "thrust bearings" much less are any bearings "thrust bearings" by default because they are "ball bearings".
As for the "thrust here" marking on your example, they indicate which side of the bearing assembly must be "supported" and is capable of transferring thrust TO rather than which side can be subjected TO "thrust". And thrust "capacity" is ALWAYS subject to rotation speed, lubrication, cooling and "duty cycle".
All deep groove ball bearings are designed to handle axial thrust. All thrust bearings in aeroderivative gas turbine engines are ball bearings. We must be using different definitions. No need for the quotation marks.
most important thing to keep in mind: these are not piston engines.
Have you visited the Waikato river yet in New Zealand? (I noticed your jet boating videos but im not too sure about the jet boating community here in the North Island). Biggest river in NZ and I can watch the tourist jet boat shooting upstream from where I work.
We were in the southern part of the South Island. Spent a couple hours in Auckland ,though. Nice place, your country is.
The weather, the scenery, and the people are all fantastic. I'm waiting for a chance to return.
Holy crap!!! A $20,000 bearing????? Are you serious?
So do the pitches of the blades in the compressor of a single shaft engine differ greatly to those in a twin shaft engine?
20000$!! Ok.. I expected them to be expensive but gees.
Didn't thought bearings was still made for these old engines and might be some part of the reason for the sick price perhaps. Sure Mil spec and all as well but still..
Dude... the two engines on a 777 are over 20 million dollars each.
Their parts are not cheap either, and they are all in full production.
True, just surprised by the price.
Im curious how the number 4 bearing works. It looks like the rear support fir the HP shaft but is mounted on the LP shaft. Wouldnt the entire bearing assembly just spin?
Yes. Both shafts are turning at different speeds, but in the same direction, so the bearing inner race turns at LP speed, and the outer race turns at HP speed, which is higher.
Hi Jay Z, thanks for your excelent educational videos. I have a question about bearing clearence at jet engines. If you rebuild an engine and replace bearings, is necesarry to check axial and radial clearence? If yes how do you do it and what are limits of clearances? Thanks for explanation.
In terms of multi spool engines and the RR Trent engines. How does this compare to a RR Trent? Is the Spey system the same kind of system used in the 2 shaft GE 90s? From what I understand the RR Trent is a 3 spool engine, or have I misunderstood something? BTW, when do we get to see the Grenda 14 in action? I'm really curious to hear how the electric starter sounds compared to the huffer start-ups. Thanks for the super cool vids:)
And since you pointed out that this is the place for nice and interesting details ;-) here is a minor correction:The CFM56 has never been installed on the A330, however it is a very common powerplant on the A320 series.
Furthermore these are missing numbers for blades/vanes installed on LPC/Booster
Stage1--> 24 blades/108 vanes (on older versions i.e. CFM56-3 also 38 up to 44 blades)
Stage2--> 74 blades / 136 vanes
Stage3--> 78 blades / ""
Stage4--> 74 blades / ""
Greetings from Germany
your videos really help me a lot. I am an apprentice of a MRO.
I wanted to ask, For the impingement cooling of Turbine blade, is the air taken from defuser.
Cooling air is taken of the compressor, at a stage where the pressure is right to cause the desired flow rate. It can be tapped off the outer case, or it can be transferred throught the center of the shaft.
@@AgentJayZ Thank you.
Just throwing a guess out there, the reason they might call those front 2 bearings collectively 3 is to keep it consistent with the station numbering for the engine overall. While it's actual location looks like it would be station 25 (between the LPC and HPC), since it is for the HPC it would make sense to call it 3.
As interesting as ever....
One thing I was wondering (please forgive my lack of engineering knowledge), in a turbofan engine (like CFM56), does the gearbox take power from the high pressure or low pressure system?
Watching your video's has made me wish I did aeronautical engineering at university...... I ended up doing Business instead.
nicely done! I had wondered about how the bearings were arranged on multi-spool engines myself.
Fine! I've dug deep enough into the archives and watched videos until I'm slightly sick of turbines to know I'm going to keep enjoying this in small but steady doses in the future.
*subscribes* Keep up the good work.
@AgentJayZ Ah, I see, the ball bearing can provide force that prevent the shaft from moving either forward or backward. Since at first it has the word "thrust" on only one side of the race, I thought it is only designed to withstand force from one direction along the axle
As always Jay,thank you so much for sharing! Great video! Can't wait to see more ;-)
Jay, why does the thrust bearing for the LM1500 come vacuum packed? Isn't it just another piece of metal like the rest of the engine which is always exposed to air? I was thinking maybe corrosion prevention?
@carlosmax50 Soon...
Very nice I’m impressed with your explanation wow
why do jets such as the one in the video I just watched about the CFM56 have red stripes on the engine nacalle advising the location of the high pressure turbine location? just curious.
A larger fanned variant of this engine (the TF41) was used in the A-7 Corsair II. The exposed first stage is one of the reasons it was referred to as a "maneater." Careful out there.
Now you've seen at least two places. Anyways, I appreciate the replies. I'm looking into finding something cool to trade for a VDI possibly, if you're still making those. :)
Thank you a lot for this explanation! I'm an Aerospace Engineering student and thank to you i finally understood how these bearings work!
The CFM56 has an air turbine started. It's similar to one of the videos on this channel except that it has it's own lubrication system inside with an oil pump.
Very informative. Covers everything in general. Translate techy terms well.
(B +). No doubt the best yet on this topic.
Thank you for this video. As you said yourself, most videos, animations and articles leave more questions than answers but you have demystified it.
I am sure that , too late to me attending the watching of your great video but I am lucky now to be one of those attending your video you are great man, go ahead really we need your kindly support we appreciate these knowledge. thanks for every things that you sent to us
Jay: What are some of the differences between the Spey as seen in this video and the Allison TF41 that powered later models of the A-7 Corsair II?
Nicely explained. Bet a triple shaft engine would be far more complex.
@AgentJayZ Ah cool. Thanks for taking the time to respond, and for taking the time to make your video's in the first place.
Do any jet engines/gas turbines use other bearings than ball- or roller bearings? Foil bearings for example?
zapfanzapfan journal bearings in Reduction Gearboxes .....and Accessory Gearboxes. ....and oil pumps. Check out a PT6A. ...and JT15D
The engine controls the HP system with fuel flow. HP system rotates the LP via the the turbine (no mechanical connection).
Two questions. Do both shafts turn the same way? Also, any idea what kind of axial forces the shafts have to withstand?
Awsome! Thanks for referancing this vid. It answered all my questions!
9:34 $20,000!??! HOLY FUCKING CHRIST
Well it's worth it.......
Can you tell me how the disk attached to the high pressure shaft is kept firmly in a stable position? 11:06
Which books do you recommend to study about the assembly of twin shaft gas turbine engines?
Thanks for your videos, they are very useful! :)
Typically the discs are bolted to the shaft. I have a video about some very good books. If you type books into the search bar on my channel page...
@@AgentJayZ Thank you Sir, Ive already watched the book video, they are exactly what I'm looking for !!!! :D
Once upon a time, you were in favor of protecting mesh. Love your videos man, congratz
the KC135 originally had the J57 the same engine as the B52, upgraded to TF33 then cfm56. it is not an 707 it is narrower and shorter.
michael mooney The 707 design was an updated KC135. The two are so closely related, that I call them the same plane. They are probably more similar than a 747-200 is to a 747-400...
+AgentJayZ Like its sibling, the commercial Boeing 707 jet airliner, the KC-135 was derived from the Boeing 367-80
jet transport "proof of concept" demonstrator, which was commonly
called the "Dash-80". The KC-135 is similar in appearance to the 707,
but has a narrower fuselage
and is shorter than the 707. The KC-135 predates the 707, and is
structurally quite different from the civilian airliner. Boeing gave the
future KC-135 tanker the initial designation Model 717.[
I believe the first production two spool engine was Bristol-RR Olympus, but its a turbojet rather than a fan. It is probably also worth mentioning that RR RB211s and Trents are 3 spool engines.I know some two/three spool engiens have different sections turning in different directions. Is this the same with all multi-spool engines or do some have hp and lp sections turning in the same direction?RB199 is a 3 spool design where the low and intermidiate stages turn in one direction and the hp goes in another.
+Kokoro Kimochi The P&W J57 was a two spool turbojet before the Olympus, and so was the Orinda Iroquois
+Kokoro Kimochi This video is about bearings in 2 spool engines. Mention it if you feel the need. The RB211 has even more bearings
I didnt know that. Thanks for the extra knowledge +AgentJayZ
Hi AgentJayZ! I've just found this video - and I readily admit that I've yet to watch most of them. Bristol Aero Engines, as the company was then, claimed that the prototype of what became the Olympus 100 series engine was the first twin-spool engine in the world to run. When I get back home (I'm in Singapore again), I will check my archives.
The bearings are constantly lubricated with oil jets. There are good videos about that on this channel.
@saxonlight
and that's not counting all the stators and EVERYTHING ELSE...
very impressive engineering
Thanks you very much sir 🙏👍👍👍👍