LOW vs. HIGH PRESSURE COMPRESSOR and SINGLE SPOOL vs MULTI-SPOOL ENGINES
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- Опубликовано: 9 май 2024
- An explanation of the terms "LOW PRESSURE COMPRESSOR", "HIGH PRESSURE COMPRESSOR" and SINGLE SPOOL vs. DUAL or TRIPLE SPOOL engines.
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Finally understood all these engine variants and I can honestly say I won't be confused ever again. Thanks you for making it plain and simple!
Hello MIK Cold, I'm glad you found it helpful and "Plane Simple"...👍 Thank you for taking the time to let me know.
@planesimple8514 that was a very well taught description on basic function of each unit from section to section. Very helpful.
Thank you very much Kevin. I appreciate it.
Thanks for taking the time to write in and give me some positive feedback.
I love your in-depth understanding and crystal-clear explanations! Perfect for ATPL and airline interview prep. You've earned my subscription! :)
Thank you very much for your kind words. Good luck at the airlines and welcome to Plane Simple.
Thank you so much sir, really. You're incredibly good at giving explanations
Thank you so much! The continuous explanation helped me a ton thank you, great teacher
Great job, I've had some interest in building a jet engine from scratch using my own design but was really clueless of how they actually worked. Thank you for sharing. Blessings to you
Thank you for your kind words terrillblair. I appreciate it. I'd love to see what you come up with for your jet engine design.
Been very interested in gas turbines for forever but I never knew what all the stages were.... thank you sir....
Most easy and simple explanaition.. i know them for awhile but now its so clear for me
Great explanation. Could you tell me which is that book ? or if it is a manual?
This answered my question phenomenally! Apparently the 8083-32A completely blows past passed this information. Do you have the resource you are teaching from in PDF form or a link to where I can buy it? Thank you!
Great video Thank you very much!
Pink Salmon, thank you!
What book is that you're using!? Those color illustrations (air flow?) on that next page look intersesting! I'm thinking it might seal the deal for us slow learners!
would it be more good if you could also explain the reasons for high compressor and low compressor alongwith the video. Excellent video anyway Helped me a lot. 6 hrs in class= 20 min video here.
Great Video Sir. Thank you
Thank you. I appreciate it.
Thank you that was a super b explanation
Thank you.
Amazing video. Thank you
Thank you for the positive feedback.
Brilliant thank you
Thank you, I'm glad you liked it.
Thanks for the nice comment.
Great video explaining very clearly something that it is not always easy to understand. I´d like to point out a couple of inaccuracies. In the single spool engine what you call the first stage stator is probably the front bearing housing frame, or the VIGV (variable inlet guide vanes). It is difficult to tell because the drawing is very schematic, not a detailed blueprint. The first stage stator is located after the first stage rotor, not before. In a compressor stage the rotor always comes before the stator, as opposed to a turbine stage in which the stator comes first. But as I said the drawing does not make easy showing this.
On the other hand, in the three spool engine, what you call the low pressure compressor is actually the intermediate pressure compressor. There are three elements in the front end: the fan, the intermediate pressure compressor and the low pressure compressor. On the rear end in turn we have the high pressure turbine, the intermediate pressure turbine and the low pressure turbine.
Hello Laertes, you are absolutely correct on both accounts. On the single Spool, I'd say those are more inlet guide vanes than a bearing housing since the struts don't actually reach the center hub, but then again, in a 2D drawing, if those guide vanes touched the center hub then they would cut off the air path! LOL... This is too simplified of a schematic to show those details, but yes, I did get the order of the vanes and rotors backwards. Thank you for the correction.
On the triple spool, I'll admit that I kind of lost my train of thought a time or two and couldn't find the right terms as I was recording. I don't script the videos(as it's painfully obvious), so mistakes and omissions won't be a rare thing, but hopefully won't be too many. Although at one point in the video I did call the fan "compressor spool #1", low, intermediate and high pressure compressors are the correct terms.
Again, thank you for the corrections and for adding to the knowledge base of this channel.
@@planesimple8514 no worries, your videos are great. Perhaps a good addition to this video would be a comparison between 3 spools turbofans (Rolls-Royce engines) and 2 spool ones (General Electric and Pratt & Whitney)
@@laertesl4324 thank you for little clearification and specially about Intermediate pressure compressor, i was looking for the this term . Video is excellent and helped me for my B1 licence.
Very nicely and easily explained.....
Thank you very much Jabulani mthembu, I appreciate it.
By the way, I like your name. It's very pretty.
hey could you tell me what book / manual this is , I'm trying to learn the parts of a jet engine to make one myself
wowww it was very very cool 😎 i can ununderstand it right now thank you .
I'm happy to hear that.
Thank you.
Thank you!
Well, now I know what a high pressure compressor is, but what about a Power Turbine? Is a power turbine just the turbofan part of the spool at the end of the GTE? In my school, they broke them up into HP turbine and Power Turbine. Are those two separate spools of the same turbine?
Why do some engines have two compressors and others just one? Are two better and the single compressor engines outdated or are there unique beneficial characteristics of each engine that make one appropriate in one setting and the other better for other uses?
Thank you legend
Thank you Bolt valley.
Thanks you explained very clearly
Thank you pimrawansaikao. I appreciate it.
Thx so much
Thanks for explanation
My pleasure.
How can they NOT be mechanically connected? Aren't they geared? Are there hydraulic couplers (like a torque converter)?
That's exactly it, fluid coupling. Remember that air is a fluid.
A torque converter is a liquid fluid coupling, a turbine engine uses a gaseous fluid(air).
Imagine if you had two fans facing each other, one powered ON and the other one OFF. The one that is ON blowing on the blades of the one that is OFF. Wouldn't the one that is ON cause the one that is OFF to start spinning too? Yet they are not mechanically connected. You just made a fluid coupling. That's the same thing that happens in a turbine engine, only at much higher pressures, temperatures, and is contained within a duct, not open like the example of the fans.
I hope this makes sense.
At time 10:23 there is a slight error concerning the nomenclature of the different spools of this three-spool high-bypass turbofan. The best example of such an engine and the only three-spool engine that was up to now produced in large numbers is the Rolls-Royce Trent family of engines. There the N2 spool is not called LP or low-pressure, it is called Intermediate Pressure or IP. On the N1 shaft there is a compressor with one or two stages just behind the fan. Those are called booster stages or it can be called the low-pressure compressor.
Hello Ernst Schütz, you are absolutely correct. I just went back to that time stamp and verified it.
Thank you for the correction.
As it is plainly obvious, I don't pre-script my videos and as such errors like that do slip through occasionally.
I appreciate you taking the time to write in and for adding to the topic.
@@planesimple8514 Thank you for your positive reactin. I wish you all the best.
thanks you very mach.
Hi sir can i get the name of book that you have used in this video
Hello, thanks for the video just to know, what is the name of the book you are using?.
Thank you. That book is the JEPPESSEN POWERPLANT TECHNICIAN book.
Thanks
After watching this video, I gain more deep knowledge of jet engine.
very nice explanation ..what arrangements do modern passanger air liners have ...single or multiple?
multiple
Wow thank you, this is most helpful.
Thank you Ian Strydom, I appreciate it.
can you please make a video about variable bleed valve ,variable stator vane and inlet guide vane if that possible .and by the way this video is amazing .you explained n1,n2 and n3 so simple. better than that ,i do not think so .go ahead
Thank you very much for your kind words. I appreciate it.
That is a great suggestion for a video but one that may take a while to make since we now I don't have access to engine cutaways that I could use to show those things, but I'll keep it in mind for the future, in case the opportunity comes along.
Again, thanks for the suggestion.
@@planesimple8514 two ways to get a variable rotor ... by design ... thus the multicurve profile of the vane .. think of it as stacking many slightly different wings on top of each other each one best at the air flow and speed of their location (slower closer to middle faster on the ends) you can also make them one shape and slightly rotate the vanes to get more compression or in a turbine more energy into the compressor .. this allows you to get more optimal engine and fuel performance form the same vanes ... each stator stage redirects air into the next rotor at the best angle for use ... so traditionally they are static BUT can be variable as well as the rotors would need a different angle of pass through than the static stator would allow .. the guide vanes are the First set of stators on the engine and all they do is stop the air intake flow swirling (to a degree) ... although they are technically stators they are not there to compress they are there to smooth out the airflow so it is more usable ... the normal start of jet turbine engine is guide vane rotor stator rotor stator and so on ... the stators JOB is to direct the air at the best angle for the rotor to work with it and its angle of exit is always equal to the optimum angle of the rotors leading edge airfoil while the rotors job is to compress the air which heats it and speeds it up ... while the tunnel they are rotating in compresses the airflow some and heats up the air ... the combined work of each rotor and stator section with the tunnel are what make the engine able to do work ...
a bleed valves general purpose is to remove supersonic airflow from the compressor stage before the combustor because lighting fuel at greater than mach 1 (340m/s at sea level) is a royal pain in the butt ... so the combustor only uses slowed down air flow (under supersonic) and with the blunt body shroud it makes air spin backwards to the direction of desired travel slowing it down further and giving a nice easy place to keep a stable flame going once ignited and it is that flame that provides heat which provides Potential energy (like sitting at the top of a toboggan hill and not going ... until you push off you are full of potential energy ... once you push off that potential is converted into Kinetic energy .. which is what the turbines do ... the unused potential energy then pushes against the outside air turning the last of it into kinetic energy called thrust ... even the air bled off is added to this for cooling of the sidewalls and added thrust ... a compress or may take 20c air and compress it to about 800c .. and then the combustor burns it raising it to say 1700c which is just under the melting point of titanium ... which when passing turbine blades doesnt melt them and makes them spin like a pinwheel fan toy kids once had ... that spin is taking the heated energy and turning it inot rotational motion which in turn spins the shaft to spin the compressor to compress the air to make the jet go faster ..
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a good thing to read up for more information is about raleigh flow and fanno flow ... these topics give you the calculations and ratio comparisons for many things that are needed inside a jet engine ... of course there is also basic aerodynamics for the airfoil shapes ... and fluid dynamics( raleigh and fanno) and metallurgy ... and chemistry (specific heat of some fluid) and of course material characteristics ... and of course thermodynamics ... and needless to say Geometry ... for the miles of math you will need to use to design an engine ... Just one rotor stator section has a math equation about 4 miles long and that gets recalculated about 14 times for the first pass in the design .. and that is done for each stage of rotor stator ... and about 6 miles long for the combustor ... and again 4 miles for each turbine ... and 2 miles for the exhaust nozzle which can also be variable and of course all the various bypass flows one needs to work in ... etc yup by the end of it you have a line of math about 200 miles long for one pass of the engine design ... and you will recalculate that several times as you make compromises for efficiency and reliability and overall output
@@0623kaboomwhy would a bleed valve be different from a blow-off valve in a car? What has sonic to do with it?
Would a single spool also be considered a ''fixed spool'' ?
Great video , you may tell ass about composted chamber ....ext ,and the material .
Thanks
Again, great suggestions. As soon as I go back to that shop I will try to cover that topic.
Ans sorry I took so long to reply.
Spools @4:40
Correct, those "rotating masses" that I talk about are the spools.
HI sir, Im studying ATC and have to research about compressor and compressor stall/ surge. Can you make a video about compressor stall/surge and how to prevent it. Many thanks from Vietnam
Hello Dung Nguyen, I would love to make a video on the topic of compressor stall. I think that is a simple principle that is very misunderstood.
But lately I haven't had a lot of time to make videos and it may take me a while before I can get to answer your video request.
I don't want to keep you waiting since you may have a limited time for your research for school.
For an instant source of information, I'd recommend some excellent videos on that very same topic by AgentJayZ on RUclips.
Look it up, he is a professional and is very informative.
Eventually I will make that video, but o don't want to keep you waiting in the mean time.
Good luck in school.
snappier puppy
it is guide vanes rotor stator rotor stator .. the first set of stators are actually guide vanes and only there to direct the airflow INTO the first stage compressor ... by taking it from chaotic flow in swirls into more straight flow ...
the high bypass engine you show as well as the other two will spin faster with more fuel ... BUT they differ in the fact that each spool works best in a different flight area ... the high by pass fan is best at low speed and low altitude and for cooling ... the intermediate spool is best for sub sonic speed and moderate altitudes ... while the high speed section is best for supersonic speeds and very high flight zones ... all the high extra spools do is make the engine work environment larger and at optimal conditions for best efficiency
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you could even make a 4 spool engine where the first spool from front is a high bypass fan then a low bypass stage for running pumps and stuff as well as low level high speed flight ... and the intermediate stage becomes a mid level flight optimum and high cruise speed performer with the high speed spool being the high supersonic portion .. add a reheat section (after Burner) and you also get a super high speed boost at the cost of fuel ... BUT each additional spool adds more weight .... and increases fuel consumption ... between the 4 engine types all on the same amount of fuel will have vastly different rates of fuel use and so large differences in time before refueling ... this is why jet liners use high bypass 3 spool engines and jet fighters use 2 spools with some using 3 with the first spool being the low bypass spool for low end flight and cooling ...
Thank you 0623kaboom.
Incoming air is as calm as it gets. The intake should not induce swirl at any angle of attack. The guide vanes are used to create swirl. The only make sense if they are variable.
Isn't there an error in figure 3-35 in the beginning of the clip? The drawing shows a stator at the front of the intake. Aren't there always rotors at the front?
Yes! You are correct. A "stage" in a compressor consists of first a rotor and then a stator. That's a good catch.
However, those drawings being only schematics for illustration purposes only are not all that accurate to begin with.
Now, there can be non rotating members in front of the rotor blades. For example, struts, like in a pure turbojet, where there's no fan in the front. In that case, what you have is a series of struts that support the from bearing. In a schematic they are difficult to depict because they would show up as a solid wall in front of the engine.
Variable stator vanes widen the range of operation ( choke- stall ). A single stage fan on its own spool can adapt its speed to the airflow. I guess that variable stators are needed for the compressor on the same spool. I don’t even get why two spool high bypass fan is a thing.
Very nicely explained sir.keep it up. Could you please refer me the name of this book.I am a AME B1.1 student.and preparing to appear for this module.
Thank you. That book is the JEPPESSEN POWERPLANT TECHNICIAN book.
Good luck on your test.
in some models the inner compressor spins in the other direction then the outer compressor...why?
That's a good question Raptor, I don't know.
But if I had to guess I'd say it's to reduce rotational loads on the airframe, to have one spool cancel or balance the loads from the other. Or perhaps to minimize gyroscopic effects. I really don't know. But I would like to find out more.
Hopefully someone well versed on the matter will add to this comment and educate us all.
Do you know any specific engines with counter rotating spools like what you mentioned?
And again, thanks for the question.
@@planesimple8514 i dont have a specific model but look here...at 0:38 ruclips.net/video/JxkJ-FwFeVI/видео.html
You can save on ring of stator vanes on the hot side and maybe get away with less vanes on the cold side?
I just Wana know how comboster chamber works
compressed air flows in ... and is directed around a shroud so the high speed air swirls back into the area where you will light the fuel ... that slower air allows the fire to stay in that place while burning all the fuel within the length of the combustor ... (kerosene burns at a rate of approx. 30 feet/sec so the length of the combustor is just oong enough to allow for full fuel ignition as the fuel air mixture heats up it expands that expansion either compresses inside its location (eventually causing a blow out if it doesnt have a way out) or accelerates out the opening to the turbine ... as the heated air leaves the combustor it has a very high potential energy ... which the turbines convert into Kinetic energy ... as their blades redirect some of the airflow to make it spin .... causing a slight loss of energy by converting it into work to spin the front end compressor stage(s) the angle of attack will determine how fast each spool spins and thus how fast your engine will go ... because what is not used to spin turbines is used to propel you forward a la newtons law of action reaction ... yu are dumping hot fast moving air out the back so you move yourself forward ... all a jet engine is a 4 cylinder engine in an inline configuration ... they suck fuel and air in ... compress it ... ignite it and finally blow it out ... just like your car engine ... UNLIKE your car they dont use the heat to move a shaft to turn pistons they use the compressed heated air to move turbines blades IN the air stream ... which in turn rotates the compressor stages ... which push more fuel and air into the engine and eventually out of it ... which is what makes you go ...
Look up lean premixed. Rocket engines all switched to coaxial injectors for fuel and air. They look like a carburettor.
A Diesel shots droplets through the flame. The result is soot. You don’t want that. At high temperature NOx is created. So burn lean , or convert temperature to work right after the flame front ( don’t do Diesel ) . High RPM piston engine/ short combustor.
EEC .FADEC . ACCESS OF AIR TO AIRPLANE FROM THE COMPRESSOR.....
IF YOU CAN !!!🤲🤲🤲🤲
Hello Khalid, Those are great suggestions, thank you. I'll see if I can create a video covering those topics soon. Thanks again for watching and for taking the time to leave these suggestions.
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Thankyou, excellent explanation,,,