Turbine Engine: full power ... LOUD!
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- เผยแพร่เมื่อ 22 ส.ค. 2024
- This is more film of the GE LM1500 gas turbine engine running at the S&S Turbines open-air test cell.
All the noise in the beginning is made by the start cart, which is a 90Hp turbine engine. Even when you hear the LM1500 start to wind up, it's not even running until you see the heat waves coming out the back of it.
This happens when the operator opens the fuel valve at around 2,000 rpm.
In the middle of the video, when the noise in an unbearable shriek, the engine is turning just over 7000 rpm, and is blowing hot air out the jetpipe to the tune of a little more than 15 thousand horsepower.
The air flow through the engine at full power is about 150 pounds per second.
In the view of the control room screen, the numbers are as follows from left to right along the top of the screen:
EGT or exhaust gas temperature in degrees Celsius, measured just after the last stage of the turbine, which is just behind the second green steel frame holding the engine.
Next is RPM. This engine has basically one rotating shaft, and you can just barely see the 1st stage compressor blades moving on shutdown. Engine RPM is of this common shaft, upon which all compressor and turbine stages are mounted.
5,000 rpm is idle speed for this engine.
Last, on the right, is lube oil pressure, in pounds per square inch. These engines have roller bearings, not journal bearings like a car engine, so oil pressure is mainly an indication of oil flow. A lot of flow is needed, because the oil is used as a coolant for the main bearings. The engine will run with no oil pressure, except the bearings will overheat, so monitoring of oil flow is very important.
This is the same engine you see in "Starting a large turbine engine"
Note: All references to podracers will be deleted.
If you have to ask why, it can't be explained to you. - ยานยนต์และพาหนะ
The video is 13 years old and this guy is still replying to people's comments. Absolute legend.
That sounds like my ps4
Sounds like me. A lot like me. Thei
I blasted that into a ps4 mic
Ps4 is a bit louder.
If your ps4 sounds like that then you need to run because that thing is gonna blow up
Came here simply to comment about the other video. Gotta love recommendations that are 10 years old
Yes
I love the smell of jet fuel in the morning.
I like it any time.
@@AgentJayZ How does jet fuel smell anyhow? Is it different from regular gasoline?
It smells like ... freedom :-)
So much raw info in your videos, never a filler even in a video 10 years old. great channel to learn from
my pc for no reason at 2 am
I know on impeller pumps we always had to design them with prime numbers on the impeller to eliminate harmonics. One prototype spun at 310,000 rpm. It was tiny, but at that rpm it pumped a lot of fuel. I have no idea why I really like things that spin fast. I love your videos, thanks for posting! Smiles!
That sounds like an air cooled gaming pc when running at 4k
@@nuttowel8202 true
I love that wherrring sound near the beginning of this video. It reminds me of the sound the DC8 used to make as those engines really started firing up. It would build up, and let loose with this wwwwhhhooooing sound, and right after that, the jet engines would really start cranking up. Of course, you'd hear that times 4. What a wonderful sound that was. I miss those planes.
How much is the swap kit for my Honda Civic EK9.
Your car will need modifications... as this engine weighs more than a Honda civic...and uses four times that much fuel per hour.
So... how about 2.2 mil..USD.
We will require a 30% deposit, and your car for 11 months.
@@AgentJayZ what's the hardest subject you learned in AMT school. Asking cause I'm going to college to become a aircraft mechanic. :) thanks.
Hardest thing to get used to was the manuals.
If you've ever worked on your car with a Clymer manual... with pictures, descriptions of how to use the tools, and hints to make the job easier... ... ... yeah, it's nothing like that.
You will be see a lot of swearing and probly do some yourself!
@@AgentJayZ Sometimes I regret my bio major when I look at the laundry list of reagents I need. Then I read stuff like this and feel relieved that I don't have to deal with that at least.
Opening your grandparents computer from the 1980's:
Fun fact, cockatoos at their max volume are just a few decibels quieter than this.
+Lishadra at the same distance from the microphone? I doubt it.
@@AgentJayZ well according to google a moluccan cockatoo is able to make noises that reach 135 decibels! seems like lishandra wasn't kidding, what a loud bird!
A howler monkey is an impressive 140 decibels 😳
Although only 5 more than a bird, that sure is loud
@@Formula1st you have to remember that decibel is a logarithmic scale, which means that doubling the amount of noise will not double the decibels. 2 howler monkeys at 140 dB each screaming together would only reach a bit over 140 dB, so "only 5 dB more" means several times louder. I can't do the math to tell how many times more because it's midnight and I am tired.
Plenty of them are still flying. Many of them are also doing great work on the ground. The J79/LM1500 is a very successful engine line.
We fix the flyers and we keep the ground runners running.
*flash-backs to the ps2 start-up screen*
THX logo
In previous summers at the race track, we've had two jet cars from Canada compete. In 2006, they were so thunderously loud that the digital readouts that measure time and speed malfunctioned!! Even the tower vibrated, which was 60 feet away from the cars. Very impressive, those spinning turbines.
that was very informative.
i liked how your annotations came onto the screen just as i was wondering what was happening.
2007....wow
THATS OLDER THAN MY FIRST PC HOLY CRAP I JUST REALIZED
Rocky is on the ball.
The start cart (the yellow thing) is a 90 Hp turbine engine running on diesel.
It supplies air at 30 psi to the starter of the LM1500.
The LM1500 ( the "engine" ) makes 15,000 Hp at full power, which you see and hear in this video.
Over Fifteen Thousand Shaft Horsepower.
Yes, Over.
Read that part again, please.
I just thought you might like to see this, so I recorded it.
You are my inspiration.
I have explained so many times in the comments section what is going on, that I am going to edit this video.
You can not see the blades because they are moving.
And because they are not the first things in the gas path.
Stand by.
When used with a power turbine ( a separate piece of equipment ), you can generate about 15 thousand horsepower to do whatever needs to get done.
Not quite as fuel efficient as a huge diesel engine, but much smaller, lighter, and needs less maintenance.
Interesting story!
If you ever see me or any of us "cross" ourselves before going near an engine intake, it's not praying for sefety... it's checking our pockets to make sure they are empty.
This is an LM1500, which is derived from the J79.
The J79 was developed in the early sixties to be the most powerful single spool turbojet yet.
Aircraft designed to use this engine were the F-104 Starfighter, the F-4 Phantom II, and the B-58 Hustler, among others.
All were capable of supersonic flight.
The LM 1500 is an industrial ( non-flying) variant of the J79.
It's an ex-USAF aircraft stert cart. It is a small turbine engine with a large proportion of compressor bleed air.
It supplies about 90 Hp of air at 30 psi throught the blue hose, which is used in this video to power the air turbine starter motor in the nose of the LM1500.
Rest easy, dude!
Our daily experience exposes us to piston engines, electric motors, and devices powered by them.
When they start to scream, it usually means they are stressed to near failure.
Jets are different; they make screaming noises even before they are running.
Just keep in mind: what is termed 100% power in a jet is the most efficient running zone.
When you are taking off, and the engines are raging away... they could make more power...
This engine, as explained in the info section, is an LM1500. It is an industrial variant of the GE J79, which was used in the
F4 Phantom2, the F104 Starfighter, The B58 Hustler, and others.
These engines do not need to be broken in, since when assembled correctly, nothing touches anything else except the main bearings, which are all ball or roller type.
In this video, Big Al is not checking for leaks.
What he is doing is looking at the operator in the control room.
This is an industrial engine derived from a J79, which is indeed a turbojet.
The J79 was used in the F-4 Phantom II, the F-104 Starfighter, and The B-58 Hustler, all planes from the 60's, roughly.
This engine, is used to generate a large amount of exhaust gas which is converted to shaft power by another turbine, called a power turbine.
The turning shaft power is then used to perform work, in this engine's case, to pump natural gas along a large pipeline.
Even if the hearing protection covers your ears, cant the sound travel through anypart of your your head and into your eardrums?
Yes it can, and it does. I would estimate that the afterburner, at any range under 50 yards, is dangerously loud, even with earplugs in, and cup-type ear defenders worn on top of them.
any idea of what dB SPL it would land at? this is a surprisingly resonant sound, how much energy is being lost to resonance?
The A-10 uses two GE TF-34 engines, a medium-sized turbofans. The Civilian equivalent is called the CF-34, and is used by the Canadair Challenger-type small twinjets that are popular with regional airlines.
The CF/TF- 34 is one of my favorite engines for the sound it makes. You can really hear the screaming of the turbine, and to me, it just sounds like a hot-rod in the sky.
This beats the loudest video on youtube!!
It's a real strain to listen to this with the volume on full - ahh that's better...
The green frame surrounding the engine is made of structural steel and is bolted to pilings driven 8 feet or so into the ground. The concrete floor has been poured around these pilings.
The engine is held at its normal attachment points by the green frame.
S&S Turbines does supply engine support to the North American Eagle.
They use a GE J79 built by us to power their car.
The Discovery Channel did a show on the S&S facilities a few years ago...
This footage is similar, but was shot by me, and the engine here is a GE LM1500, which is the industrial variant of the J79 flight engine.
The hot exhaust gases produced by the LM1500 are used to turn a separate piece of equipment called a power turbine. The output of this arrangement is roughly 15,000 horsepower.
Technically these are not engines, but gas generators.
One major component that the LM1500 would neet to become a "jet engine" is the nozzle, which is the part of the exhaust duct which tapers down to accelerate the exhaust as it leaves the engine. Gases are spit out back; the engine is thrust forward.
This engine is used to power a natural gas compression facility.
Both American teams which are currently striving to break the world land speed record are running cars which use the J79.
The J79 is the aircraft engine from which the LM1500 was developed.
This is a nice machine, nothing like the sound of a turbine at full noise. Great video, Thanks for sharing!
eight I-beams driven about 15 feet down into the ground as pilings, concreted into the pad on which the whole test cell is built.
The engine holding frame is bolted to that with 16 3/4 inch structural steel bolts.
@springfield770 The LM1500 is the industrial variant of the J79. it is used to produce a large quantity of hot gas. The J79 is equipped with a nozzle, which uses the pressure and heat in the exhaust gas to accelerate it to a high velocity, resulting in over 12,000 lbs thrust without afterburner.
The LM1500 shown here, does not have a nozzle and transmits its exhaust gases to a separate power turbine, which uses that energy to turn a shaft with 15,000 Hp.
This being an industrial gas generator, it does not have a jet nozzle.
We use a tailcone that provides a restriction to the exhaust, and measure the pressure the engine builds inside it.
These engines make about 18 to19 psi tailcone pressure at full power.
The LM1500, derived from the J79 turbojet, was built by GE, and has been out of production for decades. It is "obsolete", but they will sell you an modern LM2500 for several million dollars.
If you want one of these, you need to look in the aftermarket.
That's us.
We have some,and we have parts to build more. They don't cost anywhere NEAR that much.
I believe GE's website still has information on the LM1500 in the "Industrial and Marine" section.
The oil reservoir for this test sits on the ground. In order to prime the oil pumps on the engine, we lift the oil to their level.
We do this by capping the reservoir, and pressurizing it with air to about 3 or 4 psi.
Once the engine monitoring computer shows the operator that there is oil pressure, we release the pressure on the res, and remove the cap.
You see Big Al leaning down, to look under the engine for the signal from Brian that we have oil press.
I hope this clears things up.
The flames are from the start cart. It has a 90 hp turbine engine in it, and the fuel nozzle is dirty. This causes a rough light off, which is not unsafe, but also not normal.
The nozzle was cleaned the next day, and it has been starting flame-free ever since.
There are two ways to manage airflow in a compressor that is running below its design point, i.e. at less than its best rpm.
One is to use bleed valves, which is what Rolls Royce does, and the other is to use variable stators, which is what GE does.
Back in the 50's, when project engineer Gerhard Neumann and his team were designing what was to become the J79, it was called the VSXE or Variable Stator Experimental Engine.
Legend has it that his wife called it the "very sexy" engine...
The LM1500 is used in natural gas compressor stations.
There are quite a few still running, because the engine that was intended to replace it, the LM1600, is not a reliable powerplant.
The LM1600 is based on the F404 jet engine.
im suprised u stood so close to that engine at full power.. i've seen the GE1000 motor used in F-16s tested in a hush-house and they are freakin scary with that suction.. u got guts gettin that close...
Yes, the VIGV's are used to control airflow into the engine at less than maximum power.
In an industrial situation, they are mainly employed to ensure reliable airflow from start up to full power.
Usually industrial gas turbine engines run at their rated output ( ie: WFO )
All true.
The core of a turbofan is essentially a turbojet.
Another turbine is added to drive the fan.
In an industrial setting, this extra turbine is called the power turbine, and is actually separate from the core. It is used to drive a load, like an electrical generator, instead of the fan of a turbofan.
Most industrial engines (technically: gas generators) that I know of are slightly modified turbojets for this reason.
The engine is shown at varying power levels throughout the clip. It is at about 5500 rpm when the control screen is shown, so that would be at just above idle power. At full power, or about 7200 rpm, the EGT readings are around 900.
@AgentJayZ so much power, it's really amazing. Thanks for the comment back.
Yes, and yes. And also yes, the GG4 is based on the J75, which is/was one of the largest turbojets ever made. ( not THE largest, for all you nit-pickers!)
We are about to test anothee RR Olympus, but there is already a vid by me on the last one. It is rated at 42MW, and it is an exciting engine to be around.
If you happen to know where there are any J75 P-19W engines laying around, in any condition, please let me know, OK?
We could use a couple.
It’s going hard full power keep up the good work engine!
@Dookiedolf The engine seen in this video is used to produce a large amount of high velocity gas. Technically, it is not an engine, but a gas generator.
This high velocity stream of gas contains a lot of energy, and is used to turn a power turbine, connected by a short duct to the gas generator.
The power turbine is connected via a shaft to a centrifugal compressor which is inside the pipeline and moves the gas through it.
The power turbine is a separate piece of equipment.
@bestamerica This is an LM1500 industrial powerplant that does not go into an aircraft, but it is the same core as a J79, which was used in the F-104 Starfighter, the F-$ Phantom ll, and the B-58 Hustler.
The aircraft engines have all the fuel controls, fuel pumps, generators, and instruments on board.
With industrial engines, all those systems are off-engine as part of the facility where the engine is installed.
@Dosalt They do, that's why we're in the business of keeping them running.
Newer military turbofans have the same or better performance, and are about twice as efficient... but they also cost about 20 times as much as the flight version of this engine - the J79.
This engine is used to turn a power turbine on the ground, which creates 15 thousand horsepower. The unit being tested here powers a natural gas compression station which moves Gas in a pipeline from Canada to the US.
If you can recognize it from the sound, I'm impressed. Yes this is an LM1500, which is derived from a J-79. All the big parts that are screaming away inside, and the cases that hold all that fury together... are all exactly the same as a J-79.
This is an LM1500, which is a non-flying industrial engine derived from the GE J79.
It may sound like an old DC-8 because there is another derivative of the J79.
It was a non-military version, used to power the Convair 880 and a few DC-8s.
It was called the CJ-805.
As far as I now, there were no 737's powered by the JT3D. Those old loud, smoky engines you used to see on 737-200's are P&W JT8D's.
The JT8D was also used on the 727, DC-9, and also the MD-80.
You don't really have to be close to enjoy the sound of a turbofan. I have A-10's flying over my house all day long and I love that screaming noise.
The LM1500 was used in a couple of destroyer sized ships, but I don't know of any ships using them now.
Usually it's the LM1500s bigger relative, the LM2500 which is used in Navy ships and cruise ships.
The LM1500 was put into a couple of locomotives in the 60's, and the were hugely powerful.
After about a decade of service, they were retired and not replaced.
Unfortunately, the fuel economy of a gas turbine only compares well with piston diesels when it is working at full power.
@JoshG1976AZ This engine is an industrial, ground-running version of the J79 turbojet. The J79 powered the F-104 Starfighter (1 engine), the F-4 Phantom II (2 engines), and the B-58 Hustler (4 engines). All were supersonic aircraft of the 60's and 70's.
Thanks for uploading and the comments in the video.
Sir you best teacher jet engen I like you
Do what you like. The flow of events that make up reality are indepependent of belief and hope. They just happen. In this case happened. About four years ago.
.."carry on, as if normal",,,
This video for some reason gets a lot of views and questions, so I have tried to put as much info in the description as I can. I've got some way better test videos posted, but somehow this one attracts all the attention. Cheers!
I think the LM stands for Land/Marine, and yes the LM1500 has been used to power destroyer-sized ships.
The engines we have worked on have all been land-based industrial versions so far...
This engine generates a high-velocity stream of exhaust gases.
A short duct would connect the back of this engine to a power turbine, which turned by the stream of exhaust. The power turbine is connected by a shaft to an electrical generator or other mechanical load.
My laptop when I play coolmath
Lol
That’s my old pc when I play cyberpunk
Now it’s just like a lil wind bc new pc
This is an industrial engine, derived from the GE J79 turbojet, which was used to power the F-4 Phantom ll, the F-104 Starfighter, the B-58 Hustler, and also powered Craig Breedlove's Spirit of America ll.
We have tested J79s at the S&S test cell, and I have posted videos of those tests...
We work on industrial "aeroderivative" turbine engines, and once in a while we do special projects on aircraft engines for airshow demo teams, land speed cars, and other customers.
Most industrial engines are modified versions of highly successful turbojets, because turbofans are not used in this way.
Most of these engines were designed in the 50s and 60s.
These new engines are lighter, more fuel efficient, and have far better throttle response.
@JoshG1976AZ The LM1500 is the same engine, minus all the fuel pumps and generators used in an aircraft. All those functions are supplied by the installation "skid".
LM1500s are used to supply power to generate electricity, pump oil or gas in pipelines, and to power ships.
Rated ot 15,000 Hp, give or take , depending on many factors.
A civilian version of the J79, called the CJ-805, was used in the DC-8 and Convair 990 passenger jets of the 60's
The start cart - or huffer - contains a small turbine engine of about 90 Hp output.
It takes a bit of time, as you can hear, to get up to full power.
When it does, I flip a switch, and a valve opens to divert some of the output of its compressor to that big blue hose.
This happens at about 17 seconds in.
The noise at 18 seconds is the hose being pressurized to about 30 psi, and the 1500s air turbine starter beginning to move.
Yes. I didn't explain it here, but this is an expansion of another video: starting a large turbine engine". There you will find detailed info on the LM1500.
The word you left out is "industrial".
The LM1500 is the turbomachinery core of the J79 adapted for industrial power use: generating electricity, powering compressor stations for gas and oil pipelines... even powering ships.
This is in fact a test for future use.
This engine passed its test after an overhaul, and is now used to power a compressor station, pumping natural gas down a large pipeline from Canada into the US.
This engine is derived from a J79, slightly modified, mainly by removing a lot of external, flight-related accessories.
Then it's called an LM1500, and it weighs roughly 3,500 lbs.
@MrBeavisBeavis The green stand is structural steel, held to the skid by a dozen 3/4 inch bolts. The skid is bolted to pilings set 20ft deep in the ground, and covered with a concrete pad. It's all very standard material and methods of any steel-framed building.
I was part of the testing crew for the GE 90 115B, put that sucker out there and see what kind of hole it makes in the landscape. During one of our tests (I think it is here on youtube) it threw a 459 lb chunk of rock 15 ft @ just past idling RPMs.
@asshatnowhere159 This engine was near full power at 7000 rpm. In service it would run up to 7200. This is an industrial version of the J79, which was used in the F4 Phantom II. In military use it would be used up to 7450 rpm.
Awesome! I'm taking A&P classes. Turbine engine overhaul is this summer. I can't wait!
5*!
@poweredparagliding
No journal bearings, all roller or ball. Also turbine engine oil is made to handle extreme heat . It's very low in viscosity and is used more as a coolant for the bearings than anything else.
Plus, the oil pump is usually driven off the gearbox, which is run off the main rotating shaft, so when the engine is turning, oil is pumping.
I put that shot in there, a bit longer than needed, to try to give an indication of how loud it is.
This engine is closely related to the J79, which powered the Phantom II and Starfighter in the US Air Force.
When it's running wide open, it's a mighty impressive thing to hear and see.
It's much louder than the video makes it seem.
@Taimak77 These engines are used to provide the power to natural gas compressors. They are placed at various points along major pipelines to move the gas along.
Another use is to power electrical generators in what are called Natural Gas Power plants. Each engine can produce about 8-10 MW, depanding on the efficiency of the power turbine it is matched to.
This question has been asked before. Here's the answer:
The part known as the fan is the usually the first and often only stage of the low pressure compressor of a two-shaft or two-spool engine. These engines are also called turbofans and they are the modern large airliner engines.
This is a single spool turbojet, and has no fan.
The first thing you can see is the front bearing housing strut, and it does not move.
This question has been asked before, so I'll answer it again.
The part know as the fan is the usually the first and often only stage of the low pressure compressor of a two-shaft or two-spool engine. These engines are also called turbofans and they are the large airliner engines.
This is a single spool turbojet, and has no fan.
The first thing you can see is the front bearing housing strut, and it does not move.
@citydriver The air turbine starter motor turns the gearbox of the engine.
Jet engines have gearboxes that are attached to the main shaft and are used to run oil pumps, tachometers, fual pumps, etc.
Normally all those accessories turn because they are attached to the engine's main shaft via the geabox.
If you turn the gearbox via an outside source of torque, you can turn the main shaft of the engine, and if you get it going fast enough, you can start it...
Yes. This was the very last time it spit flames. That day I removed the fuel nozzle, cleaned it, and ever since it's been much more civilized on startup.
We all miss the flames, though!
... I edited this footage over two years ago. looking at it again, you might be right.
We're really cooking, but the engine isn't really making that shriek, is it?
You're the only one to have ever made that comment, so good on ya.
I couldn't see the control panel from where I was filming, so I had to guess.
cool! keep up the good work and I wish them and you all the best. I got my fingers crossed that the team is sucessful in setting a new land speed record!
@Htown20XX
That's a very common thing to not see the "load" for turbine engines.
This engine at full power is loaded by the 150 lbs per second of air that it is accelerating from a speed of zero to just below sonic velocity.
It takes over 15 thousand horsepower to do that.
This engine made more than that in this test.
@IEKUKATAKA Excellent to hear from you, and yes, you are totally right.
We call them nozzles as well. To be totally stiff about things, I would also call them "turbine inlet stators" or "turbine inlet guide vanes". They are exactly as you describe.
I was meaning the jet nozzle in my oversimplified response.
J79 turbojet derivative. Great engine, wonderfully simple. Thanks so much for the vid, and your explanation. I learned quite a bit!
One man's cacaphony is another's symphony.
@Reggae45s This engine makes a high-velocity jet of exhaust gases. This is passed thru a short duct to a power turbine, which uses this energy to turn a rotating output shaft. The shaft is mechanically connected to a large centrifugal compressor that compresses natural gas in a pipeline station.
A jet engine on propane is a beautiful thing.
I've been lucky enough to see inside the combustor of an Avon burning kerosene, and also an Olympus burning Propane.
I could see the actual fuel nozzles.
Roll Royce calls the "burners"
@DadinWestchester They have, and were the most powerful locomotives ever.
Fuel consumption does not decrease when idling with a turbine as much as it does with a rattlebox ( piston engine), so they weren't economical unless they were really working hard.
Running an electrical generator is one of the most practical and popular uses for gas turbine engines running in industrial situations.
The load is consistently high, and highly consistent.
@ismasamov55 this is an industrial test cell. The vaporizer uses a small amount of fuel, but more importantly, it does it safely.
Propane has an evaporation temp of -39 degrees C. It would be dangerous and unnecessary to run it anywhere near the 750 degree C exhaust of the engine.
Our test cell is not near any residences, but from a few hundred yards away, an engine test sounds like an airliner taking off.
Each run is usually about 15 to 30 minutes.
If you check the RPM on the screen, you'll see those temps are at 55 to 57 hundred rpm. That is idle for this engine.
We have very little footage of high power running. i hope to remedy that soon!
@labranjames All the engine data required to test the engine is listed.
The top three boxes read from left to right:
EGT - which is the temperature of the exhaust gases measured right behind the turbine.
RPM - of the compressor and turbine rotors. They are coupled and turn as one.
Lube oil pressure - measured at the oil pump outlet and given in psi.
@IEKUKATAKA
What I was referring to above is the tapering section of the exhaust pipe that causes the gases to accelerate as they leave the engine, increasing the forward reaction, or thrust on the engine.
This is an industrial gas generator, and it's main functional difference from an aircraft jet engine is that it does not include such a nozzle. Its gases are turned to thrust by the blading of an attached power turbine, to rotate a shaft.
I want to ask a question. In the description you say that the engine is turning just over 7000 rpm, which is about 7000/60=117 revolutions per second. I expected therefore to hear a noise with frequency of 117 Hz, but I hear a high pitch sound of 2300 Hz. I am wondering where this noise is coming from. (I am building a RC-heli which I want to sound like a turbine heli).
There are more than one blade per stage of the compressor. Each stage has a different number, so it makes a lot of different frequencies. All of them are greater than once per rev.
@Htown20XX
Yes, this particular engine has a nominal rpm limit of 7200. The absolute military "do not exceed" limit is 8400 rpm. going there even for a second turns the engine into scrap.
@shreiberrulz Behind the engine here is concrete until about 20 feet back. After that, it's loose dirt. Very little of it gets kicked up because the exhaust stream is in the shape of a very gradual cone. By the time the edge of that cone touches the ground, the stream is moving at what looks like maybe 250 mph or so.
The grass doesn't like it, but not much destruction takes place.
Sure, if we tilted the exhaust down a bit, we could blow a hole in the ground...
@bigtoyota479 Yes, only the other turbine turns a shaft, to which is attached a centrifugal compressor, and that's what moves the gas down the pipeline.
that other turbine is called a power turbine, because it extracts the power from the engine's exhaust, but it is not actually attached to the engine, except for the duct for conducting the exhaust gases.