Can a jet engine "run away", Starting airliner engines, Pri & Sec fuel systems, Why the little holes, Cooling air, Centrifugal compressors, How we fix engines.
AgentJayZ - your videos are pure gold. I love the idea of not using diagrams but getting people to use their imagination. Without doubt one of the best channels on TH-cam. 😊
JZ, If ya want a show, then it's a great idea to introduce fuel before it's suppose to be. I was manning the RSU at Holloman when a pair of transient 105's took the runway for takeoff. As you know, when lead lit the burner the water injection kicked in. Well....some dumb ars filled the water tanks with JP4. Fire came out EVERY hole in that airplane. Every inspection panel blew off, the guys went over the side of a 12 foot high airplane that was still rollin'. It was a real Chinese Firedrill. But after the fire went out the engine was still runnin' and the airplane was on it's own. The airplane came to a halt about 7000' just off the runway still in idle. No more fire, just sittin' there idling. The guys wouldn't get near it and nobody else knew how to shut it down. They let it idle until it flamed out. Don't add fuel to the compressor section! It's a real fireworks show! Much, much better than shockcones. Keep up the good work.
I've told this story before. Years ago, a BAC 1-11 went down on a German autobahn/highway soon after take-off, because the water injection tanks for its Spey engines had been filled with kerosene, instead of a water/methanol mixture. The additional fuel burned the turbines out in minutes.
hello Jay! thank you for your reply! That part about the combustor liner i knew about(thank god) White hot is not Good!! unfortunately some of those engines being built that way,we have this forum in internet called JATO,where discussions about the different builds come up and when such extreme builds show Up,it gets discussed and advised how to build correctly! thanks Jay for your input,really truly appreciated!! best regards Stephan Höglund
Hello, Jay. I believe that the 707 was the first transport that could be self-started using stored (on board) compressed air. It would start one engine. The remaining three were bootstrapped by tapping compressed air from the running engine. I also recall that the 727 was the first transport having an APU. It was located in the right-hand wheel well. The tailpipe exhausted upwardly through the wing root area. If there was a "torching start" (i.e. the fuel was introduced too early in the start procedure) some passengers would get quite a show.
Even the simple & modest J44 has its share of 'little holes'! I appreciate the instruction/refresher course, as usual, so thanks again & Merry Christmas! Cheers! DD
Two historical examples of a jet engine "running away": (1) Early prototype if a jet engine by Frank Whittle, which was in a stationary test stand. Whittle did not know it, but unburnt fuel had pooled inside the engine. When the engine speed got too high, Whittle shut off the fuel line, but the pools of fuel continued to vaporize and burn, causing the engine to run away. I think the engine almost exploded but did not, and Whittle was lucky to have no injuries. (Source: Some BBC documentary on Frank Whittle.) (2) I forget which airliner flight, but you can Google for it: One of the airliner's jet engine had a massive oil leak (not a fuel leak, but an oil leak) somewhere around or before the turbines. But like fuel, jet oil can burn, and it caused the rotor to massively over-speed. Engineers doing forensics on the engine found rotor parts that were so "oversized" they were out-of-specification. The parts had stretched from the massive centripetal forces from spinning too fast. (Source: Some episode of Air Crash Investigations.) In any case, both of these examples are extremely unusual. (btw, my lay-person's understanding comes from watching videos, so AgentJayZ, please corrected any mistakes and/or misunderstandings.)
1) ... an experimental device that was eventually to lead to a production turbine engine. Good example, but can not be included in the answer. 2)... yes, but an extremely unlikely event. Good comments..never say never...
Please see my answer to Juha Tuomala in respect of your para. (2). The only component that became oversized and went out of spec was the IP turbine disc. At around 140percent overspeed, it dilated to such an extent that it burst into three 120 degree segments. That's classic for a disc overspeed failure. PS The flight was QANTAS QF32.on 4 Nov 2010.
Frank Wittle's first jet engine test "ran away". There was excess fuel in the combustion chamber that caught and exploded! There is a great video/documentary!
the only Jet engine run away I heard about was with Frank Whittle and his early jet engine. Long story short, Fuel was pooling in the combustion chamber at shut off and the next time they started the engine it would fire up and run away immediately. they then found out that if they ran the engine long enough, the residual fuel was burnt off and then they could control it
Dispatch of airliners is usually allowed for a few days with broken APU, in which case they use an external start cart (aka "huffer") to start the first engine, and use cross-bleed from the running engine(s) to get the rest going. All large and large-ish airliners except the 787 have air-turbine starters because they have substantially higher power-density than electric motors. The 787 can offset for that a bit because it uses a combined variable-frequency starter-generator, removing the need for the heavy constant-speed integrated drive generator on more traditional designs.
Awesome video yet again Jay, and up to 90, wow. MAybe for the century mark, the ton or whatever you want to call it, the 100th video you should tackle the compressor stall video? I have looked on the net and the description of what's going on is convoluted into something that makes no sense and you have a great gift to explain things so even simpletons like me can understand what's going on.
And btw, AgentJayZ, thanks for an interesting response to my question. It's an interesting niche your business occupies somewhere on the continuum between FAA-regulated airliner maintenance shops and.... Merry Merry -
It is interesting to look at the evolution of combustors. First note the size (volume) of the early can combustors compared with the double annular GE90 combustor. The next thing to notice is how the air injection hole sizes shrunk. I believe one of the early design criteria was to minimize the combustor pressure loss. Hence a lot of big holes. The down side of this was that the injection jets (air through the holes) was "lazy" and tended to dance around. Hence a propensity for high turbine pattern factor and hot streaks. Newer designs target around a 3% pressure drop for the combustor with well defined dilution zones and jets, with remarkable turbine pattern factors. A Jay said in previous comments a lot was trial and error. However some of the advancement came from computational fluid dynamics advancements in the late 1980s. The gas turbine is truly a modern marvel!
Never was interested in jet engines, but came up across your channel, and got hooked on it. Great subjects, and explanations. Keep it up 👍 Out of curiosity, how much one of those used machines run for ? 😆
The pressure can rise as air travels toward the outside of a centrifugal compressor. The centripetal acceleration of the air following a curved path creates a pressure gradient similar to linear acceleration as with Bernoulli's principle. Thanks for the video!
Of course it does. The diffuser case is part of the compressor, and the compressor... compresses the air. Huge surprise there, eh? All of the compression happens as the air travels to the outer diameter of the centrifugal compressor. That's how they work. That's why they are called "compressors". Unless of course, you mistakenly referred to the impeller as the compressor, in which case you are not correct. But otherwise you are totally correct!
Haning studied centrifugal compressors a LITTLE bit, in principle AgentJayZ is right, velocity (speed actually) is the only desirable change. However, in practice, due to the work being applied to the fluid, it heats up measurably, not significantly, while it is accelerated. Pressure DOES increase measurably "inside" the impeller. However, the ratio of speed vs heat is veeeery large. Also, depending on the geometry of the impeller-diffuser pair, the leading faces of the blades (the ones that strike the air, that do most of the work) are at an elevated pressure compared to the trailing faces. It all comes down to action-reaction: if all faces had the same pressure, there would be no reaction force opposing the impeller - it would not consume any energy.
I did of course use the wrong term when talking about the impeller. Do you know if that is just to keep the impeller temperature under control, or is it just more effective aerodynamically to have the pressure rise happen in the case?
Great video full of interesting info but I have to wonder, the engine standing up behind you I've notices for some time how beat up it looks at the exhaust nozzle, did it get left out in a bad hail storm?
Hi Jay, just recently discovered you. I am happy to see you. Good to see you are still producing and interacting with your TH-cam account after all these years. Wow. I love jet engines, so a big heart felt thanks for sharing so much of your knowledge. I became interested in jet engines after getting my mind around Bernoulli's Law and the aeroplane propeller, and had started to wonder how much of the forward thrust of the jet engine is generated off the forward facing surface of the turbine rotors, like it does with an aeroplane propeller? Now, from being shown inside the jet engine, by yours truly,I am thinking, it seems very little. Where, apart from the mass/velocity equation of the air being pulled into the intake manifold, most of the forward thrust is generated purely by the push out the back of the turbine engine by Newton's Laws. Is this correct, or is there a situation where the front most rotor has been designed to utilize Bernoulli's Law to pull the aircraft forward?
Frank Whittle had the first gas turbine runaway. Fuel had accumulated in the combustors during a runup while in development. It just kept accelerating even when the fuel was cut off. Gas turbines and diesels are similar in that they almost always have an excess of air for combustion. Just add an uncontrolled fuel source like an oil or fuel leak and away it goes.
Whittle's incident happened with a research engine with a very simple fuel system. It was also of such low power output that a few litres of fuel presented a significant source. Modern airliner engines have hundreds of times the power output, and therefore have higher fuel consumption. Jet engines simply do not have runaways, a fact that refutes your claim.
Wonderful video (as normal) So on the holes in the engine, what if one gets plugged? (Just kidding) On the engine run-away question, the only one I am aware of is the prototype that Whittle was working on in his lab. The fuel controller was not set up properly and it just kept increasing RPMs until the fuel was cut off. Now being 193? I can only imagine that the fuel pump was from a piston engine (but that is a guess only). What I find amazing is that the F-22 Raptor uses a cartridge starting system. Not as bad as the B-52 of the B-57 -- man those things smoke. Keep up the great work, I love your videos. Always wanted to be a Jet Dude, but instead ended up being a desk jockey.
A bad front oil seal failure could cause a jet engine to run away as oil would be drawn into the combustor and burn in addition to the metered fuel from the injectors, Another starter system is AVPIN, a small rocket motor burning isopropyl nitrate, the exhaust gases spin a turbine through a reduction gear that then turns the jet engine
The first V-22 Osprey crash that occurred in Washington DC, into the Potomac River was caused by pooled hydraulic fluid in the nacelle pouring into the engine when it rotated the nacelles to helicopter mode. 7 people died
I gotta say love your channel I ALWAYS learn something new! The cylinders in Han Solo's pocket are supposed to be code cylinders. Word on the street is that the prop makers on some of the older movies used RA Stephens' dosimeters (usually used to measure radiation dosages on atomic workers) I found a thread on the replica prop builders forum that goes into it a bit www.therpf.com/showthread.php?t=85709 neat stuff!
Hello at first a happy 2017 i have a Question if an compressor of a turboshhaft engine is bigger And the Blades are longer does is suck more air And is the output of the sound level than bigger??? Than a small compressor?
I have been recording in 1080p 60 fps for years. And not realizing that the software I've been using to edit the vids defaults to 30 fps. I only recently set the production of my final edits to 60fps. I wish I woulda been smarter.
We had one accident in Airforce where one PW F100-200 was running away. The reason was that the feedback rod between the fuelcontroller and fuelpump was failing. So from idle to max power it was accelerating to quick with to much fuel and accelerated to about 200% rpm and then the turbine blades was also flying away and engine and airplane went into fire.
A diesel running away normally means you cannot shut it down because the fuel keeps getting injected into the cylinders. When you shift it to neutral it will rev up furiously even at low throttle positions because there's no load attached. When you cannot stop the fuel getting pumped into a jet engine's combustion chamber, it will just kinda run, but not run away,, because you cannot put a jet engine to neutral gear. If the jet engine has a variable propelling nozzle that will not close, you will get some sort of a low-load situation. But normally you will never get a jet engine to full throttle when the nozzle does not close, because the nozzle is connected to the power control systems (well, I'm sure you knew...). There where many incidents with early Starfighters having trouble with nozzles that did not close. They just lost all of the thrust and all the pilots could do about it was to eject immediately. Wow... sorry for the length-ish text, and I hope I managed to write some readable English as well.
i had diesel runaway the turbo got an oil leek and had to still the engine to stop it lucky for me my truck was a manual even then it took 1 km to stop it on the breaks
I would think the amount of fuel a jet engine uses a full power a runaway would be unlikely. They also seem to not have all that much oil and much less oil pump than fuel pump so it'd be unlikely to go into runaway and cause overspeed damage before running out of oil. A diesel used much less fuel, with much less power, and has lots of oil. So in a runaway situation it's more likely to happen as well as overspeed and come apart well before running out of oil.
Hi, In the evolution of jet engines,has there been a marked change in the quantity of compressor air used for cooling purposes especially in the cooling of the combuster? I guess that whilst engines are running hotter than before, changes in materials have to some extent countered this.
Well in the combustor the cooling air makes no difference to the performance as it is ejected out the back as thrust, most of the wasted air is in cooling the turbine nozzles and blades
Ok, I'll have to see that movie again now :-) On the runaway engine. Is there a valve in the fuel system that gives the operator overriding authority or does the engine run itself with only requests for certain power from the operator? I saw a video from an emergency landing with a large passenger plane with a damaged engine where they could not shut down the engine. It wasn't running away or anything, I think it was just idling or maybe a little more than that but it kept going and going so the control system must have been damaged and nothing could stop the engine getting fuel. They tried to stop the engine by spraying water into it with fire hoses, I don't remember exactly how they managed to finally stop it but I think they sprayed foam into it.
The manual has all the procedures and all the allowances for things like burning, cracking, and distortion. In some places, cracks are bad. In some they are OK. Some cracks can be repaired by welding. Some combinations of cracking, burning and distortion will be reason to replace the liner with a new one.
way back late 1970's or early 1980's a MIG-25 was tracked by NATO radar to a speed in excess of MACH 3 and was later reported that the engine was damaged beyond repair. MIG-25 is not supposed to exceed MACH 2.9 is this a case of engine runaway? I have also noticed that some airplane specification includes never exceed speed limitations as a warning to pilots. does this mean that in excess of this speed limit a possible engine runaway situation may occur?
When you said "If the air going into the intake is of a flammable mixture", and that made me wonder... what if someone sprayed Nitrous/NOS/N2O into the intake? I realize N2O is an oxidizer, not a fuel, so on its own it just increases the oxygen, which I believe is known as "dry spray". But then you can spray in some fuel along with it, known as "wet spray" I think... P.S. Sorry if you answered this, I've only started watching your videos recently, haven't watched them all, YET!
No. It would have no effect. With fuel, you would be introducing fuel in the wrong spot, and you could get fire in the compressor. Also, engine power is limited by heat, and the engine runs at max temp. If you rigged up something that allowed you to spray more fuel in manually, the fuel control would back off its contribution in order to keep the temp within limits. Remember:"the human is not in control of the engine, but he/she does get a vote" - the Fuel Control.
Hi Jay, great videos about turbojet engines. But i have a question..... on 17:47 in this video when you say that the pressure at the intake and the pressure at the outlet of impeller (for centrifugal compressor) is the same. Is that right or not? Because I remember from school that inlet pressure is smaller than outlet and also all the diagrams of centrifugal compressors are showing that outlet pressure is greater than inlet. Thx
You are getting lost in the confusion resulting from imprecise terminology, and also a bit of other things. A centrifugal compressor consists of a rotor, a housing, and diffusion passages. The rotor increases the speed of the air and discharges it into the diffusion passages, where the kinetic energy of the air is transformed into pressure. So, there is a difference between saying "the exit of the compressor" and "the exit of the rotor". Does that help?
To withstand the tremendous reaction force during the testing of a Jet-Engine how the frame on which the JetEngine is mounted anchored? Can this frame be portable...i mean can it be relocated without much installation work ?
Old video I know, but as a point of interest the UH-60 has an APU which provides bleed air to start the engines as discussed, but the APU starts using a hydraulic start motor driven by an accumulator using pressurized nitrogen. Are there any big jets you are aware of, perhaps in industrial settings that use hydraulic start motors or are they limited to smaller applications?
Hydraulic start on industrial engines is one of the ways it's done. My series of vids on the Rolls Royse Olympus features the engines being started with their hydraulic starter. Hydraulic power is supplied from an external source, not an accumulator on these bigger engines.
Hey J:I believe the Whittle Eng. Prototype had the Problem of Runn'in Away.Shutting it Down B-4 Destruction was the Secret 2 its Success there-by making it a viable alternative 2 Recipicat'in Types.B-4 my Tyme, but that's what We were taught.Rule Britannia!!! lol Planker.
Diesel and Jets have self sustaining ignition. I suppose if you can't control the fuel it will runaway (over RPM or not able to shut down). Both of these could be failure of fuel control to shut down or provide excess fuel. Jet or turbojet engines have a fire handle and just, pulling the handle will shut down fuel, hydraulics, pneumatic, electrical). This is in addition to the normal fuel cutoff, which if it fails would not allow engine to shut down, thus fire handle. Turning the handle discharges fire retardant.
From what I can guess you mean, those are the bosses into which the locator pins fit. Nothing is bolted or welded into place, to allow for expansion and contraction due to the fact that these parts work in nearly red hot condition. The pins are arranged radially, to hold the liner in position axially, but to allow for thermal expansion.
@@AgentJayZ thank you very much for replying, as you can guess I know nothing of jet engines lol, but your channel has been paramount in expanding an interest I had but had no idea where to start, thanks again, I wish you the best and keep the excellent content coming.
I'd like to ask a question. Is the maximum speed of an gas turbine limited to the speed at which the compressor blade tip reaches the speed of sound, and does this same knowledge apply to the turbine-power turbine?
At take-off rating, the tips of the fan blades of the big high by-pass turbofans are supersonic, causing that very characteristic buzz-saw sound. Otherwise, compressor blade tips speeds are typically limited to below the speed of sound, because the shock patterns that would be formed would result in aerodynamic losses. However, the speed of sound increases in direct proportion to the square root of the absolute temperature. Consequently, the higher the temperature, the higher the speed of sound and the tip speeds in turbines are typically well below the local speed of sound.
The old Detroits had what was called solid racks. If one injector would stick at full fuel, then all of the injectors would be held in full fuel, and the governor can't control rpms. The blowers had emergency flapper shut downs on them. You hoped that the engine would shut down. This is one way of a Detroit Diesel run away. I think the question might have been related to no fuel control run away. Just wondering on lost of fuel control.
On Quantas flight 32 an oil pipe broke in the engine, fed oil to into the combustion area and made it run so hot that one of the turbine discs disintegrated and punched holes trough the wings and fuselage, I guess that can be counted as runaway ?
i don’t really know anything. but say you have a turboprop engine and you take the propeller off so the engine has almost no load and the fuel controls was stuck open would it run away then.
Not likely. It's called a fuel control because it controls the fuel. It's not just a valve, and the human does not directly control the fuel flow. The pilot gets a vote, but the final say is in the hands of the fuel control.
AgentJayZ but for sake of augment if the fuel was getting in there some how. with out load would the engine just spin faster and faster? i understand that they probably make it almost impossible for the fuel controller to allow that to happen. thx for replying to a old video very cool of you.
Unlikely The fuel control controls the fuel. If a PT speed sensor failed and sent a zero speed signal to the fuel control, it might want to add fuel to increase that speed, but it's not that simple. There are multiple control pathways, and they all have an influence on the fuel control. For example there would be a separate overspeed mechanism on the PT, which does not use the speed sensor, but would trip at a set value and either limit or shut off the fuel to the gas generator. Engine stops.
The fire suppression system is part of the aircraft, not the engine. There's a video I made called Bleed Air which may help answer your second question.
theres a u tube of an F-14 [ i believe] air refueling and the basket separates from the hose. as the hose undulates some fuel goes in the intake and u can see a compressor stall/backfire occur.
Is the spark on going as long as the engine is running .or is the spark just to start the flame then stops the spark and the engine continues running after
Once the candle is lit, it no longer needs a spark. Often ignition is left on until after takeoff, because even though it's a very unlikely event that the flame should go out, the consequences are extreme, and so a little wear on the ignition system is an acceptable cost.
I found 2 videos that you all might like. #1 The J-57: th-cam.com/video/C1-7xaUTLEY/w-d-xo.html #2 The J-58: th-cam.com/video/F3ao5SCedIk/w-d-xo.html Both of these videos answer a number of FAQs Enjoy :)
Excellent video as usual. I would like to ask two questions. 1) Is it possible to convert every aviation engine in to an Industrial engine? 2) Whether any Turbo Prop engine has been converted into an Industrial engine ever? Any example. If not, why? Thanks for sparing your valuable time.
1) There are many different configurations of aviation propulsion gas turbine engines. All of them can be converted into industrial use, but not all of them easily. Only a few configurations have been converted, and not by shops on an individual basis. "Converting to industrial use" is done to the design by the manufacturer. It's a process carried out on an engine design, not usually on an individual engine. 2) The P&W PT-6 is an aircraft turboprop engine, and is also available in industrial form, as the ST-6 from P&W. The RR 250 is a turboshaft engine for helicopters, which is also available as the 250-B-17 turboprop version for light aircraft. A company called MTT sells a firefighting pump skid which uses an RR250 to power the water pumps. That would be an example of an aftermarket conversion from aviation turboshaft to industrial turboshaft.
The Bristol Proteus turboprop engine, which originally powered the Bristol Britannia airliner, was probably one of the first aircraft to industrial (and marine) gas turbine conversions. It produced 2.7MW when used for electrical generation and 4,250SHP when used in fast patrol boat and hovercraft applications. It was already in service when I joined Bristol Siddeley Engines as an undergraduate apprentice in 1962.
The Rolls-Royce Tyne turboprop engine, which originally powered the Vickers Vanguard and Canadair CL-44 (and other aircraft), was converted in the late 1960s into the Marine Tyne. The Proteus needed virtually no design changes, as it was a free power turbine engine and the 1500rpm output from its aero engine reduction gearbox could be connected directly to a 4-pole generator for 50Hz AC power. However, the Tyne aero engine LP spool also drove the prop, so a major redesign was required. The aero engine's reduction gearbox was removed, the 3-stage LP turbine was divided to give a single-stage turbine driving the LP compressor and a 2-stage free power turbine, with a 'hot end' drive to a separate gearbox. As a young designer at R-R's Industrial and Marine Division, I designed some of the external accessory mountings.
For the runaway question, what about an industrial engine that is designed to have a load on the same shaft, but the linkage breaks or an inattentive operator starts it without checking if the load is connected. Would the engine runaway in those circumstances?
No. The power turbine is independent of the gas generator. The fuel control senses the load (PT) shaft speed, and also the GG shaft speed. It will reduce fuel to the GG if the load shaft increases past the set point. It will also try to keep the PT speed at the setpoint if the load is too great and the speed begins to fall. But it will not allow the GG to overtemp or overspeed. On engines where the mechanical load is driven on the same shaft, the fuel control keeps the speed of that shaft, so if the load breaks off, the control would reduce fuel, and the load is to great, it will add fuel up to the temp limit, but will not burn up the engine in an attempt to drive an excessive load.
Industrial and Marine Olympus power turbine rotors had a mechanical overspeed trip arrangement mounted near the output coupling flange. If all other control system features failed and the power turbine did overspeed, a collar on the shaft would go eccentric and trip a lever, which pulled a cable to close a valve, which shut off the fuel to the gas generator.
A "Runaway" Diesel is when the diesel air intake is obstructed (super dirty air filter) and the engine starts sucking up and burning the crankcase oil. I had it happen to me, and it was impossible to shut down accept by downshifting until stalled out.
In my case, the throttle was closed (foot off the gas pedal) and the car was accelerating as it was spewing black smoke running off crankcase oil. I had to stop the car and dump the clutch with the brakes on to shut it off. If it had been an automatic transmission, it would have had to run crankcase dry and seize up the engine to shut off.
Do jet engines typically rotate in the same direction? in the case of a multi-engine aircraft, do any of the engines ever rotate in opposite directions to counter balance engine torque? Love Jet Questions!
This is an old question! Typically, R-R engines rotate in an anti-clockwise (counter-clockwise in N American speak) direction, viewed from the rear. However, other UK engines have rotated in the opposite direction. For example, the Armstrong Siddeley Sapphire rotated in a clockwise direction, as did DeHavilland engines. US engines typically rotate in a clockwise direction, viewed from the rear. However, there are numerous two- and three-spool engines that have counter-rotating spools. I'm not aware of any jet engines that have opposite rotation for left- and right-hand installations on multi-engine aircraft. However, the Airbus A400M military transport turboprop does have opposite hand rotation props on either side. Try finding a clip on TH-cam.
PS I've had to explain this before, but in a jet engine, there is minimal toque to be reacted by the engine mountings. The torque generated by the fan and compressor stators is approximately equal and opposite to that generated by turbine stators.
Thank you for taking the time to respond! I apologize for the repeat question, but that one has been nagging me for a while. They are amazing machines...
PPS I've also mentioned this before, but whilst the main engine mountings may not be taking a significant amount of torque during normal operation, they are typically designed to take a massive amount of torque. After all these years, I'm rusty on the design rule we actually applied at R-R, but, from memory, we designed the mountings to take the torque generated by the engine rotor seizing in either three or five revolutions. That was probably a massive 'overkill', but the objective was to ensure that the engine didn't wrench itself out of the airframe, if it did seize.
When a new aircraft is being developed do they also develop an engine for that aircraft or do they find an engine that fits the specs for the new aircraft? or are engine manufacturers always designing and creating new engines that the aircraft manufacturer can choose from? Don't know if you know the answer but never hurts to ask.
Rusty Films alot of aircraft are made with an engine in mined. Some are made with a specification. And they ask engine manufacturers to fulfill the requirements. But aircraft and engine design are closely linked assuming it the first aircraft to use that engine. The next "generation" aircraft may be made to fit a previous generation engine.
Hey. I've got a big question. I am building (0 budget prototyping) a plastic pyrolysis machine with supplemented ethanol I make and want to know how you could, cost effectively, produce around 25-75 kw with a turbine. Anny thaughts?
Zero budget? 100% chance of failure. Small budget would be figure out a way to make gaseous fuel from plastic, then burn it in a small turbine engine. Smallest budget: burn that fuel in a small torch or heater fist.
@@AgentJayZ that's exactly what I was thinking. I have a plan to use the gas from the pyrolyzer at full temp so it does not need to be cooled into a distillate. Would it be advantageous to use the exhaust to heat the pyrolysis chamber (or turbine intake) along with the burner? How low power could a gas turbine be before it is pointlesly efficient compared to a petrol or diesel piston powed generator?
@@AgentJayZ do you have any thoughts on the turbine wrightspeed has designed to be a range extender on electric trucks. Or cheap centrifugal compression turbines for electric powered vehicles in general?
P&W makes a very successful range of turboprops called the PW100 series. Two separate centrifugal compressors in series. Each is driven by a separate turbine, so technically it is two single stage compressors, not one two stage assembly. Good description if you put PW 100 in your Google search bar. Make sure it doesn't get auto-corrected into PW1000g, 'cause it'll want to do that...
may I ask you how to calculate the composition chamber like if the hot sections torbine diameter 18 inch will be 200 holse by size 0.6 inch per primary hole make the answer example the composition chamber that in this vedio
Nothing you have written here makes any sense. You need to read a few books to learn a few things, so you will know that your question is meaningless. You will enjoy the learning process, I think.
Quants had an oil supply pipe rupture and feed the engine with most likely an nice atomized spray of hp oil which caused the turbine disk to overspeed and catastrophically fail. I heard of diesel Engines burning their own oil even when fuel is removed.
What, no mention of cartridge starters? Shame. Though I guess they're not used so much these days ("these days" being "in our lifetimes") and may never have been used in airliners, but still cool. Basically a big shotgun shell with no shot that pushes a piston to spin the gear the regular starter spins, rack-and-pinion style, also used on aircraft piston engines. OFC mainly used on fighters and bombers, that normally use ground power for starting in the conventional ways you explained, but might have to spin up eight J57s RIGHT NOW if war were declared.
In an engine with multi spool architecture do the spools turn opposite directions to do away with the need for stators between the different spools? Don't respond if this has been covered already, or is just plane stupid.
Not stupid. Some engines do use counter-rotating shafts. Graham is more of an expert on that subject. He is our resident Rolls Royce design engineer. ... Hold for his contribution...
Thanks, AgentJayZ! It's certainly not a stupid question: in fact; it's a great question. Years ago, at R-R Bristol, we ran a rig model of a two-stage, statorless, contra-rotating turbine, which eliminated the NGV row between the HP and LP blades - and it worked. I could be wrong, but I seem to recall seeing a cutaway GA of one of the latest US (military?) engines that had no NGV row between the HP and LP blades. With R-R's current engine architecture, a statorless turbine isn't possible, because the IP NGVs in the Trent range and the LP NGVs in the EJ200 house structural 'spokes' and services for their turbine bearing housings. However, the EJ200 is contra-rotating and there is a performance advantage, because the low camber LP NGVs have lower aerodynamic losses that the equivalent high camber NGVs in a co-rotating turbine. This is primarily the reason for the latest marks of Trent engine having a contra-rotating HP spool, so as to reduce the secondary flows and consequent aerodynamic losses in the IP NGVs.
If Combustion chamber more number in same size the thrust may change or increase or decrease. Please check it . Sir. My openion is thrust may increase.
Your comment makes no sense. What am I supposed to check? You have a great need for information and knowledge. Have a look at my video about books. Search bar on channel page.
It is suspected that the uncontained engine failure of National Airlines Flight 27 may have been a result of the crew playing around with engine throttle settings and causing the engines to overspeed. en.wikipedia.org/wiki/National_Airlines_Flight_27
Would the Black Swan event of that Qantas flight QF32 years ago where they couldn't shut down an engine for two hours after it landed be classed as a "run away"? They ended up stopping the engine by swamping it with water from a couple of crash tenders. The accepted method of stopping a diesel run away is by the use of a flapper plate or a large enough rag to over/in the air inlet to starve oxygen.
Nor would I. The engine controls were just 'frozen'. That's not much different from having a jammed throttle on a diesel or petrol/gasoline engine - with the difference, of course, that, in a vehicle, they can be disconnected from the load. PS I thought you were in Palm Springs CA, AgentJayZ? Merry Christmas and enjoy the warm weather. I'm off to Singapore (again) for a month at the end of January.
Power = Torque * Rotational velocity. So, roughly speaking (I am just guessing here), they'd use a test stand that places a retarding torque (or 'load') on the engine, max out the throttle, find the torque that has the turbine can maintain its specified RPM at, and then you just calculate Torque * Rotational velocity, i.e., power. Obviously I'd also love to see specific details though.
Hi jay, stupid question from someone with no clue about engines. If radial compressors can do 900 percent compression and axial ones only about 10 and therefore need many stages, why are axial compressors used on big planes, while radial ones are more popular on model engines? Is the advantage of radials somehow lost when scaled up?
Since you have a test cell and maybe a spare engine laying around. If I got a kick starter (pun intended) to supplied the garden hose of gas any you supplied the testicles to operate it, in the interest of science of course, could we find out if that would actually cause a run away?
I would have to ask the owners of the test cell. Any spare engines laying around are hulks, that will need about 50K of work at a minimum to get them to running shape. Test cell fee is large, and does not include fuel or any labour to set the engine up. If you can raise 100k US, and agree to cover any damages caused by catastrophic incidents, I'm sure your curiosity can be satisfied.
Ha! No need I was just pushing the funny. I've seen what happens when an axial flow steam turbine over speeds and its very bad, and they have very thick cases and no big exhaust hole at the back for parts to fly out of! Needless to say if one ever did run away you'd have heard about it!
Robert Szasz You might be thinking of QF32 where an oil leak due to a parts error caused the turbine disk to overspeed. The damage to critical wiring in the wing then led to loss of command of the outboard engine which had to be shut down destructively with foam once they landed. It was running at the last commanded throttle setting.
NoisyPlaces I think I heard of it happening on a test stand/demo turbine (for teaching purposes rather than power) I'm not surprised it has been documented at least once. It's a very very rare failure mode though.
27:20 Here's what I found about those three things in Solos pocket: movies.stackexchange.com/questions/52459/what-are-these-cartridges-that-many-characters-have-in-the-star-wars-movies Apparently, they're detonators..
@@AgentJayZ I think it's weird that everyone in Starwars is apparently just carrying around multiple detonators on a daily basis... lol. I picture before any of the guys leave for the day, the wives are like "Don't forget your detonators, honey! You left 2 out of 3 of them here yesterday - remember, you'd rather have it and not need it than need it and not have it! Smooches."
I really enjoy watching and learning from you Jay. Thank you for doing these videos.
AgentJayZ - your videos are pure gold. I love the idea of not using diagrams but getting people to use their imagination. Without doubt one of the best channels on TH-cam. 😊
It's (almost always) so quiet in your shop during your talks, but it looks like a Whole lot of work to the initiated! Thank you for sharing with us!
I always make vids outside of work hours. Lots of people do not wish to be on camera.
Yes, I love these videos! Perfect way to start the weekend!
JZ, If ya want a show, then it's a great idea to introduce fuel before it's suppose to be. I was manning the RSU at Holloman when a pair of transient 105's took the runway for takeoff. As you know, when lead lit the burner the water injection kicked in. Well....some dumb ars filled the water tanks with JP4. Fire came out EVERY hole in that airplane. Every inspection panel blew off, the guys went over the side of a 12 foot high airplane that was still rollin'. It was a real Chinese Firedrill. But after the fire went out the engine was still runnin' and the airplane was on it's own. The airplane came to a halt about 7000' just off the runway still in idle. No more fire, just sittin' there idling. The guys wouldn't get near it and nobody else knew how to shut it down. They let it idle until it flamed out. Don't add fuel to the compressor section! It's a real fireworks show! Much, much better than shockcones. Keep up the good work.
I've told this story before. Years ago, a BAC 1-11 went down on a German autobahn/highway soon after take-off, because the water injection tanks for its Spey engines had been filled with kerosene, instead of a water/methanol mixture. The additional fuel burned the turbines out in minutes.
We love your program here in the UK, and look forward to each installment. keep up the good work!
Finally found this combuster thing. This is the part thats always left off how a jet engine works. Thank you.
I saw a diesel engine "runaway", it was a roll-over, it was sucking engine oil through the PCV valve, it over revved and blew up.
hello Jay!
thank you for your reply!
That part about the combustor liner i knew about(thank god) White hot is not Good!!
unfortunately some of those engines being built that way,we have this forum in internet called JATO,where discussions about the different builds come up
and when such extreme builds show Up,it gets discussed and advised how to build correctly!
thanks Jay for your input,really truly appreciated!!
best regards Stephan Höglund
Hello, Jay. I believe that the 707 was the first transport that could be self-started using stored (on board) compressed air. It would start one engine. The remaining three were bootstrapped by tapping compressed air from the running engine. I also recall that the 727 was the first transport having an APU. It was located in the right-hand wheel well. The tailpipe exhausted upwardly through the wing root area. If there was a "torching start" (i.e. the fuel was introduced too early in the start procedure) some passengers would get quite a show.
Even the simple & modest J44 has its share of 'little holes'! I appreciate the instruction/refresher course, as usual, so thanks again & Merry Christmas! Cheers!
DD
Thanks for sharing, its very educative for those who are interested in jet engines and stuff like that.
YOU ARE MY HERO. Just like your personality and you even wicked smat. Haha
For the 100th installment of Jet Questions, can we have a winter party in BC somewhere?
Two historical examples of a jet engine "running away":
(1) Early prototype if a jet engine by Frank Whittle, which was in a stationary test stand. Whittle did not know it, but unburnt fuel had pooled inside the engine. When the engine speed got too high, Whittle shut off the fuel line, but the pools of fuel continued to vaporize and burn, causing the engine to run away. I think the engine almost exploded but did not, and Whittle was lucky to have no injuries.
(Source: Some BBC documentary on Frank Whittle.)
(2) I forget which airliner flight, but you can Google for it: One of the airliner's jet engine had a massive oil leak (not a fuel leak, but an oil leak) somewhere around or before the turbines. But like fuel, jet oil can burn, and it caused the rotor to massively over-speed. Engineers doing forensics on the engine found rotor parts that were so "oversized" they were out-of-specification. The parts had stretched from the massive centripetal forces from spinning too fast.
(Source: Some episode of Air Crash Investigations.)
In any case, both of these examples are extremely unusual.
(btw, my lay-person's understanding comes from watching videos, so AgentJayZ, please corrected any mistakes and/or misunderstandings.)
1) ... an experimental device that was eventually to lead to a production turbine engine. Good example, but can not be included in the answer.
2)... yes, but an extremely unlikely event.
Good comments..never say never...
Please see my answer to Juha Tuomala in respect of your para. (2). The only component that became oversized and went out of spec was the IP turbine disc. At around 140percent overspeed, it dilated to such an extent that it burst into three 120 degree segments. That's classic for a disc overspeed failure. PS The flight was QANTAS QF32.on 4 Nov 2010.
Always informative thank you for your time J
Fantastic as always
This is a great explanation.
Frank Wittle's first jet engine test "ran away". There was excess fuel in the combustion chamber that caught and exploded! There is a great video/documentary!
Yes, we know the story. Thanks for the correction that is not a correction, OK?
the only Jet engine run away I heard about was with Frank Whittle and his early jet engine. Long story short, Fuel was pooling in the combustion chamber at shut off and the next time they started the engine it would fire up and run away immediately. they then found out that if they ran the engine long enough, the residual fuel was burnt off and then they could control it
Thanks I truly understand now how centrifugal compressor work in function from that explanation.
Dispatch of airliners is usually allowed for a few days with broken APU, in which case they use an external start cart (aka "huffer") to start the first engine, and use cross-bleed from the running engine(s) to get the rest going. All large and large-ish airliners except the 787 have air-turbine starters because they have substantially higher power-density than electric motors. The 787 can offset for that a bit because it uses a combined variable-frequency starter-generator, removing the need for the heavy constant-speed integrated drive generator on more traditional designs.
very interesting jay,always a pleasure to watch your videos,especially when your talking jet engines😀
Awesome video yet again Jay, and up to 90, wow. MAybe for the century mark, the ton or whatever you want to call it, the 100th video you should tackle the compressor stall video? I have looked on the net and the description of what's going on is convoluted into something that makes no sense and you have a great gift to explain things so even simpletons like me can understand what's going on.
And btw, AgentJayZ, thanks for an interesting response to my question. It's an interesting niche your business occupies somewhere on the continuum between FAA-regulated airliner maintenance shops and....
Merry Merry -
It is interesting to look at the evolution of combustors. First note the size (volume) of the early can combustors compared with the double annular GE90 combustor. The next thing to notice is how the air injection hole sizes shrunk. I believe one of the early design criteria was to minimize the combustor pressure loss. Hence a lot of big holes. The down side of this was that the injection jets (air through the holes) was "lazy" and tended to dance around. Hence a propensity for high turbine pattern factor and hot streaks. Newer designs target around a 3% pressure drop for the combustor with well defined dilution zones and jets, with remarkable turbine pattern factors. A Jay said in previous comments a lot was trial and error. However some of the advancement came from computational fluid dynamics advancements in the late 1980s. The gas turbine is truly a modern marvel!
Never was interested in jet engines, but came up across your channel, and got hooked on it.
Great subjects, and explanations.
Keep it up 👍
Out of curiosity, how much one of those used machines run for ? 😆
How much (time) one of those used machines run for?
They will run until you cut off the fuel supply.
Thank you Sir!
Nice explanation
on the radial compressor!!! That is really hard to try and explain.
The pressure can rise as air travels toward the outside of a centrifugal compressor. The centripetal acceleration of the air following a curved path creates a pressure gradient similar to linear acceleration as with Bernoulli's principle. Thanks for the video!
Of course it does. The diffuser case is part of the compressor, and the compressor... compresses the air. Huge surprise there, eh?
All of the compression happens as the air travels to the outer diameter of the centrifugal compressor. That's how they work. That's why they are called "compressors".
Unless of course, you mistakenly referred to the impeller as the compressor, in which case you are not correct.
But otherwise you are totally correct!
Haning studied centrifugal compressors a LITTLE bit, in principle AgentJayZ is right, velocity (speed actually) is the only desirable change. However, in practice, due to the work being applied to the fluid, it heats up measurably, not significantly, while it is accelerated. Pressure DOES increase measurably "inside" the impeller. However, the ratio of speed vs heat is veeeery large. Also, depending on the geometry of the impeller-diffuser pair, the leading faces of the blades (the ones that strike the air, that do most of the work) are at an elevated pressure compared to the trailing faces. It all comes down to action-reaction: if all faces had the same pressure, there would be no reaction force opposing the impeller - it would not consume any energy.
I did of course use the wrong term when talking about the impeller. Do you know if that is just to keep the impeller temperature under control, or is it just more effective aerodynamically to have the pressure rise happen in the case?
Great video full of interesting info but I have to wonder, the engine standing up behind you I've notices for some time how beat up it looks at the exhaust nozzle, did it get left out in a bad hail storm?
Thank you for the Macho Man reference !
Nice peace sign in the background!
You are right. There are several, now that i look.
Hi Jay, just recently discovered you. I am happy to see you. Good to see you are still producing and interacting with your TH-cam account after all these years. Wow. I love jet engines, so a big heart felt thanks for sharing so much of your knowledge.
I became interested in jet engines after getting my mind around Bernoulli's Law and the aeroplane propeller, and had started to wonder how much of the forward thrust of the jet engine is generated off the forward facing surface of the turbine rotors, like it does with an aeroplane propeller?
Now, from being shown inside the jet engine, by yours truly,I am thinking, it seems very little. Where, apart from the mass/velocity equation of the air being pulled into the intake manifold, most of the forward thrust is generated purely by the push out the back of the turbine engine by Newton's Laws.
Is this correct, or is there a situation where the front most rotor has been designed to utilize Bernoulli's Law to pull the aircraft forward?
Frank Whittle had the first gas turbine runaway. Fuel had accumulated in the combustors during a runup while in development. It just kept accelerating even when the fuel was cut off.
Gas turbines and diesels are similar in that they almost always have an excess of air for combustion. Just add an uncontrolled fuel source like an oil or fuel leak and away it goes.
Whittle's incident happened with a research engine with a very simple fuel system. It was also of such low power output that a few litres of fuel presented a significant source.
Modern airliner engines have hundreds of times the power output, and therefore have higher fuel consumption.
Jet engines simply do not have runaways, a fact that refutes your claim.
Wonderful video (as normal) So on the holes in the engine, what if one gets plugged? (Just kidding)
On the engine run-away question, the only one I am aware of is the prototype that Whittle was working on in his lab. The fuel controller was not set up properly and it just kept increasing RPMs until the fuel was cut off. Now being 193? I can only imagine that the fuel pump was from a piston engine (but that is a guess only).
What I find amazing is that the F-22 Raptor uses a cartridge starting system. Not as bad as the B-52 of the B-57 -- man those things smoke.
Keep up the great work, I love your videos. Always wanted to be a Jet Dude, but instead ended up being a desk jockey.
Whittle's "lab" was a disused foundry building.
Thank you AgentJayZ!
A bad front oil seal failure could cause a jet engine to run away as oil would be drawn into the combustor and burn in addition to the metered fuel from the injectors, Another starter system is AVPIN, a small rocket motor burning isopropyl nitrate, the exhaust gases spin a turbine through a reduction gear that then turns the jet engine
The first V-22 Osprey crash that occurred in Washington DC, into the Potomac River was caused by pooled hydraulic fluid in the nacelle pouring into the engine when it rotated the nacelles to helicopter mode. 7 people died
That trek is nice :P
Best bike I've ridden.
great man
You did well profesor
I gotta say love your channel I ALWAYS learn something new! The cylinders in Han Solo's pocket are supposed to be code cylinders. Word on the street is that the prop makers on some of the older movies used RA Stephens' dosimeters (usually used to measure radiation dosages on atomic workers) I found a thread on the replica prop builders forum that goes into it a bit www.therpf.com/showthread.php?t=85709 neat stuff!
Hello at first a happy 2017 i have a Question if an compressor of a turboshhaft engine is bigger And the Blades are longer does is suck more air And is the output of the sound level than bigger??? Than a small compressor?
Did you get a new camera? This video looks so much smoother than usual!
I have been recording in 1080p 60 fps for years. And not realizing that the software I've been using to edit the vids defaults to 30 fps. I only recently set the production of my final edits to 60fps.
I wish I woulda been smarter.
We all have different skills!! Anyway, the video looks great! :D
We had one accident in Airforce where one PW F100-200 was running away. The reason was that the feedback rod between the fuelcontroller and fuelpump was failing. So from idle to max power it was accelerating to quick with to much fuel and accelerated to about 200% rpm and then the turbine blades was also flying away and engine and airplane went into fire.
A diesel running away normally means you cannot shut it down because the fuel keeps getting injected into the cylinders. When you shift it to neutral it will rev up furiously even at low throttle positions because there's no load attached.
When you cannot stop the fuel getting pumped into a jet engine's combustion chamber, it will just kinda run, but not run away,, because you cannot put a jet engine to neutral gear.
If the jet engine has a variable propelling nozzle that will not close, you will get some sort of a low-load situation. But normally you will never get a jet engine to full throttle when the nozzle does not close, because the nozzle is connected to the power control systems (well, I'm sure you knew...).
There where many incidents with early Starfighters having trouble with nozzles that did not close. They just lost all of the thrust and all the pilots could do about it was to eject immediately.
Wow... sorry for the length-ish text, and I hope I managed to write some readable English as well.
i had diesel runaway the turbo got an oil leek and had to still the engine to stop it lucky for me my truck was a manual even then it took 1 km to stop it on the breaks
I would think the amount of fuel a jet engine uses a full power a runaway would be unlikely. They also seem to not have all that much oil and much less oil pump than fuel pump so it'd be unlikely to go into runaway and cause overspeed damage before running out of oil.
A diesel used much less fuel, with much less power, and has lots of oil. So in a runaway situation it's more likely to happen as well as overspeed and come apart well before running out of oil.
Hi, In the evolution of jet engines,has there been a marked change in the quantity of compressor air used for cooling purposes especially in the cooling of the combuster? I guess that whilst engines are running hotter than before, changes in materials have to some extent countered this.
Well in the combustor the cooling air makes no difference to the performance as it is ejected out the back as thrust, most of the wasted air is in cooling the turbine nozzles and blades
Ok, I'll have to see that movie again now :-)
On the runaway engine. Is there a valve in the fuel system that gives the operator overriding authority or does the engine run itself with only requests for certain power from the operator?
I saw a video from an emergency landing with a large passenger plane with a damaged engine where they could not shut down the engine. It wasn't running away or anything, I think it was just idling or maybe a little more than that but it kept going and going so the control system must have been damaged and nothing could stop the engine getting fuel. They tried to stop the engine by spraying water into it with fire hoses, I don't remember exactly how they managed to finally stop it but I think they sprayed foam into it.
hi jay z, my question is how do you inspect the combustion liner or how do you determine his condition?
regards
The manual has all the procedures and all the allowances for things like burning, cracking, and distortion.
In some places, cracks are bad. In some they are OK. Some cracks can be repaired by welding.
Some combinations of cracking, burning and distortion will be reason to replace the liner with a new one.
way back late 1970's or early 1980's a MIG-25 was tracked by NATO radar to a speed in excess of MACH 3 and was later reported that the engine was damaged beyond repair. MIG-25 is not supposed to exceed MACH 2.9 is this a case of engine runaway? I have also noticed that some airplane specification includes never exceed speed limitations as a warning to pilots. does this mean that in excess of this speed limit a possible engine runaway situation may occur?
When you said "If the air going into the intake is of a flammable mixture", and that made me wonder... what if someone sprayed Nitrous/NOS/N2O into the intake? I realize N2O is an oxidizer, not a fuel, so on its own it just increases the oxygen, which I believe is known as "dry spray". But then you can spray in some fuel along with it, known as "wet spray" I think...
P.S. Sorry if you answered this, I've only started watching your videos recently, haven't watched them all, YET!
No. It would have no effect. With fuel, you would be introducing fuel in the wrong spot, and you could get fire in the compressor.
Also, engine power is limited by heat, and the engine runs at max temp.
If you rigged up something that allowed you to spray more fuel in manually, the fuel control would back off its contribution in order to keep the temp within limits.
Remember:"the human is not in control of the engine, but he/she does get a vote" - the Fuel Control.
@@AgentJayZ Haha, nice quote.. And yeah, that's along the lines of what I was expecting would happen. Thanks for the quick reply!
Hi Jay, great videos about turbojet engines. But i have a question..... on 17:47 in this video when you say that the pressure at the intake and the pressure at the outlet of impeller (for centrifugal compressor) is the same. Is that right or not? Because I remember from school that inlet pressure is smaller than outlet and also all the diagrams of centrifugal compressors are showing that outlet pressure is greater than inlet. Thx
You are getting lost in the confusion resulting from imprecise terminology, and also a bit of other things.
A centrifugal compressor consists of a rotor, a housing, and diffusion passages.
The rotor increases the speed of the air and discharges it into the diffusion passages, where the kinetic energy of the air is transformed into pressure.
So, there is a difference between saying "the exit of the compressor" and "the exit of the rotor".
Does that help?
Just watched the trailer to see those chip detectors!
To withstand the tremendous reaction force during the testing of a Jet-Engine how the frame on which the JetEngine is mounted anchored? Can this frame be portable...i mean can it be relocated without much installation work ?
Video is called Our Engine Test Stand...
Old video I know, but as a point of interest the UH-60 has an APU which provides bleed air to start the engines as discussed, but the APU starts using a hydraulic start motor driven by an accumulator using pressurized nitrogen. Are there any big jets you are aware of, perhaps in industrial settings that use hydraulic start motors or are they limited to smaller applications?
Hydraulic start on industrial engines is one of the ways it's done. My series of vids on the Rolls Royse Olympus features the engines being started with their hydraulic starter.
Hydraulic power is supplied from an external source, not an accumulator on these bigger engines.
Hey J:I believe the Whittle Eng. Prototype had the Problem of Runn'in Away.Shutting it Down B-4 Destruction was the Secret 2 its Success there-by making it a viable alternative 2 Recipicat'in Types.B-4 my Tyme, but that's what We were taught.Rule Britannia!!! lol Planker.
Diesel and Jets have self sustaining ignition. I suppose if you can't control the fuel it will runaway (over RPM or not able to shut down). Both of these could be failure of fuel control to shut down or provide excess fuel. Jet or turbojet engines have a fire handle and just, pulling the handle will shut down fuel, hydraulics, pneumatic, electrical). This is in addition to the normal fuel cutoff, which if it fails would not allow engine to shut down, thus fire handle. Turning the handle discharges fire retardant.
It happened to a early A380 when a oil feed line broke in one of the RR engines. that caused a runaway and total turbine failure.
On the annular combuster shown in this video what are the brackets on every other fuel nozel?
From what I can guess you mean, those are the bosses into which the locator pins fit. Nothing is bolted or welded into place, to allow for expansion and contraction due to the fact that these parts work in nearly red hot condition. The pins are arranged radially, to hold the liner in position axially, but to allow for thermal expansion.
@@AgentJayZ thank you very much for replying, as you can guess I know nothing of jet engines lol, but your channel has been paramount in expanding an interest I had but had no idea where to start, thanks again, I wish you the best and keep the excellent content coming.
I'd like to ask a question. Is the maximum speed of an gas turbine limited to the speed at which the compressor blade tip reaches the speed of sound, and does this same knowledge apply to the turbine-power turbine?
At take-off rating, the tips of the fan blades of the big high by-pass turbofans are supersonic, causing that very characteristic buzz-saw sound. Otherwise, compressor blade tips speeds are typically limited to below the speed of sound, because the shock patterns that would be formed would result in aerodynamic losses. However, the speed of sound increases in direct proportion to the square root of the absolute temperature. Consequently, the higher the temperature, the higher the speed of sound and the tip speeds in turbines are typically well below the local speed of sound.
Was it myth that the first Whittle Engine ran away? I remember this from a very old black and white film.
Thanks.
The old Detroits had what was called solid racks. If one injector would stick at full fuel, then all of the injectors would be held in full fuel, and the governor can't control rpms. The blowers had emergency flapper shut downs on them. You hoped that the engine would shut down. This is one way of a Detroit Diesel run away. I think the question might have been related to no fuel control run away. Just wondering on lost of fuel control.
On Quantas flight 32 an oil pipe broke in the engine, fed oil to into the combustion area and made it run so hot that one of the turbine discs disintegrated and punched holes trough the wings and fuselage, I guess that can be counted as runaway ?
No. The oil did not feed into the combustion area. Please see my answer to Juha Tuomala.
Thanks
i don’t really know anything. but say you have a turboprop engine and you take the propeller off so the engine has almost no load and the fuel controls was stuck open would it run away then.
Not likely. It's called a fuel control because it controls the fuel. It's not just a valve, and the human does not directly control the fuel flow.
The pilot gets a vote, but the final say is in the hands of the fuel control.
AgentJayZ but for sake of augment if the fuel was getting in there some how. with out load would the engine just spin faster and faster? i understand that they probably make it almost impossible for the fuel controller to allow that to happen. thx for replying to a old video very cool of you.
Unlikely The fuel control controls the fuel. If a PT speed sensor failed and sent a zero speed signal to the fuel control, it might want to add fuel to increase that speed, but it's not that simple. There are multiple control pathways, and they all have an influence on the fuel control.
For example there would be a separate overspeed mechanism on the PT, which does not use the speed sensor, but would trip at a set value and either limit or shut off the fuel to the gas generator. Engine stops.
Were there any fire extinguisher in a Jet Engine? And those Air Bleed things are the ones supplying cabin pressure in a Jetliner?
The fire suppression system is part of the aircraft, not the engine.
There's a video I made called Bleed Air which may help answer your second question.
Thanks for the reply Sir. Honestly I envy you profession. It was my dream since I was a kid :)
theres a u tube of an F-14 [ i believe] air refueling and the basket separates from the hose. as the hose undulates some fuel goes in the intake and u can see a compressor stall/backfire occur.
The early F-14s had engines with very unhappy compressors. It would be interesting to see video of such an event.
Is the spark on going as long as the engine is running .or is the spark just to start the flame then stops the spark and the engine continues running after
Once the candle is lit, it no longer needs a spark. Often ignition is left on until after takeoff, because even though it's a very unlikely event that the flame should go out, the consequences are extreme, and so a little wear on the ignition system is an acceptable cost.
I found 2 videos that you all might like.
#1 The J-57: th-cam.com/video/C1-7xaUTLEY/w-d-xo.html
#2 The J-58: th-cam.com/video/F3ao5SCedIk/w-d-xo.html
Both of these videos answer a number of FAQs
Enjoy :)
Excellent video as usual.
I would like to ask two questions.
1) Is it possible to convert every aviation engine in to an Industrial engine?
2) Whether any Turbo Prop engine has been converted into an Industrial engine ever? Any example. If not, why?
Thanks for sparing your valuable time.
1) There are many different configurations of aviation propulsion gas turbine engines. All of them can be converted into industrial use, but not all of them easily. Only a few configurations have been converted, and not by shops on an individual basis.
"Converting to industrial use" is done to the design by the manufacturer. It's a process carried out on an engine design, not usually on an individual engine.
2) The P&W PT-6 is an aircraft turboprop engine, and is also available in industrial form, as the ST-6 from P&W.
The RR 250 is a turboshaft engine for helicopters, which is also available as the 250-B-17 turboprop version for light aircraft. A company called MTT sells a firefighting pump skid which uses an RR250 to power the water pumps. That would be an example of an aftermarket conversion from aviation turboshaft to industrial turboshaft.
The Bristol Proteus turboprop engine, which originally powered the Bristol Britannia airliner, was probably one of the first aircraft to industrial (and marine) gas turbine conversions. It produced 2.7MW when used for electrical generation and 4,250SHP when used in fast patrol boat and hovercraft applications. It was already in service when I joined Bristol Siddeley Engines as an undergraduate apprentice in 1962.
The Rolls-Royce Tyne turboprop engine, which originally powered the Vickers Vanguard and Canadair CL-44 (and other aircraft), was converted in the late 1960s into the Marine Tyne. The Proteus needed virtually no design changes, as it was a free power turbine engine and the 1500rpm output from its aero engine reduction gearbox could be connected directly to a 4-pole generator for 50Hz AC power.
However, the Tyne aero engine LP spool also drove the prop, so a major redesign was required. The aero engine's reduction gearbox was removed, the 3-stage LP turbine was divided to give a single-stage turbine driving the LP compressor and a 2-stage free power turbine, with a 'hot end' drive to a separate gearbox.
As a young designer at R-R's Industrial and Marine Division, I designed some of the external accessory mountings.
grahamj9101 Thank you so much for sharing your valuable expertise. Please keep on contributing with your worthy knowledge and skills.
AgentJayZ Thank you so much for getting the query cleared. Also thanks for sharing your valuable knowledge and sparing valuable time.
For the runaway question, what about an industrial engine that is designed to have a load on the same shaft, but the linkage breaks or an inattentive operator starts it without checking if the load is connected. Would the engine runaway in those circumstances?
No. The power turbine is independent of the gas generator.
The fuel control senses the load (PT) shaft speed, and also the GG shaft speed. It will reduce fuel to the GG if the load shaft increases past the set point.
It will also try to keep the PT speed at the setpoint if the load is too great and the speed begins to fall. But it will not allow the GG to overtemp or overspeed.
On engines where the mechanical load is driven on the same shaft, the fuel control keeps the speed of that shaft, so if the load breaks off, the control would reduce fuel, and the load is to great, it will add fuel up to the temp limit, but will not burn up the engine in an attempt to drive an excessive load.
Industrial and Marine Olympus power turbine rotors had a mechanical overspeed trip arrangement mounted near the output coupling flange. If all other control system features failed and the power turbine did overspeed, a collar on the shaft would go eccentric and trip a lever, which pulled a cable to close a valve, which shut off the fuel to the gas generator.
4:06 That's It!!!.....A garden hose of accelerant!...
How do some old fighter engines use a cartridge start system to start up?
Also what inspection methods do you guys use on a normal basis ie eddy current, dye penetrant, etc.?
You will find your question answered in a video somewhere in
the playlist I’ve created called Your
Questions Answered. It has a sort of index.
AgentJayZ oh ok sweet. Thank you!
Sweet fat bike!
A "Runaway" Diesel is when the diesel air intake is obstructed (super dirty air filter) and the engine starts sucking up and burning the crankcase oil. I had it happen to me, and it was impossible to shut down accept by downshifting until stalled out.
It can be from a turbo failure at which point the turbo oil feed ends up pumping oil right into the intake.
Even with a failed turbo the engine will still pull in air, like a natured aspirated engine
In my case, the throttle was closed (foot off the gas pedal) and the car was accelerating as it was spewing black smoke running off crankcase oil. I had to stop the car and dump the clutch with the brakes on to shut it off. If it had been an automatic transmission, it would have had to run crankcase dry and seize up the engine to shut off.
Do jet engines typically rotate in the same direction? in the case of a multi-engine aircraft, do any of the engines ever rotate in opposite directions to counter balance engine torque? Love Jet Questions!
This is an old question! Typically, R-R engines rotate in an anti-clockwise (counter-clockwise in N American speak) direction, viewed from the rear. However, other UK engines have rotated in the opposite direction. For example, the Armstrong Siddeley Sapphire rotated in a clockwise direction, as did DeHavilland engines. US engines typically rotate in a clockwise direction, viewed from the rear. However, there are numerous two- and three-spool engines that have counter-rotating spools.
I'm not aware of any jet engines that have opposite rotation for left- and right-hand installations on multi-engine aircraft. However, the Airbus A400M military transport turboprop does have opposite hand rotation props on either side. Try finding a clip on TH-cam.
PS I've had to explain this before, but in a jet engine, there is minimal toque to be reacted by the engine mountings. The torque generated by the fan and compressor stators is approximately equal and opposite to that generated by turbine stators.
Thank you for taking the time to respond! I apologize for the repeat question, but that one has been nagging me for a while. They are amazing machines...
PPS I've also mentioned this before, but whilst the main engine mountings may not be taking a significant amount of torque during normal operation, they are typically designed to take a massive amount of torque. After all these years, I'm rusty on the design rule we actually applied at R-R, but, from memory, we designed the mountings to take the torque generated by the engine rotor seizing in either three or five revolutions. That was probably a massive 'overkill', but the objective was to ensure that the engine didn't wrench itself out of the airframe, if it did seize.
When a new aircraft is being developed do they also develop an engine for that aircraft or do they find an engine that fits the specs for the new aircraft? or are engine manufacturers always designing and creating new engines that the aircraft manufacturer can choose from? Don't know if you know the answer but never hurts to ask.
It used to be more your second choice. nowadays it's more like your first choice.
Rusty Films alot of aircraft are made with an engine in mined. Some are made with a specification. And they ask engine manufacturers to fulfill the requirements. But aircraft and engine design are closely linked assuming it the first aircraft to use that engine. The next "generation" aircraft may be made to fit a previous generation engine.
Hey. I've got a big question. I am building (0 budget prototyping) a plastic pyrolysis machine with supplemented ethanol I make and want to know how you could, cost effectively, produce around 25-75 kw with a turbine. Anny thaughts?
Zero budget? 100% chance of failure.
Small budget would be figure out a way to make gaseous fuel from plastic, then burn it in a small turbine engine.
Smallest budget: burn that fuel in a small torch or heater fist.
@@AgentJayZ that's exactly what I was thinking. I have a plan to use the gas from the pyrolyzer at full temp so it does not need to be cooled into a distillate. Would it be advantageous to use the exhaust to heat the pyrolysis chamber (or turbine intake) along with the burner? How low power could a gas turbine be before it is pointlesly efficient compared to a petrol or diesel piston powed generator?
@@AgentJayZ do you have any thoughts on the turbine wrightspeed has designed to be a range extender on electric trucks. Or cheap centrifugal compression turbines for electric powered vehicles in general?
Hi,oil system to work jet engines ?
Is that an attempt to suggest I need to make such a video?
You might want to search my channel for lube system.
Do any engines that use centrifugal compressors have more than one compression stage?
P&W makes a very successful range of turboprops called the PW100 series. Two separate centrifugal compressors in series.
Each is driven by a separate turbine, so technically it is two single stage compressors, not one two stage assembly.
Good description if you put PW 100 in your Google search bar.
Make sure it doesn't get auto-corrected into PW1000g, 'cause it'll want to do that...
AgentJayZ
Thanks, have looked at the diagrams, looks similar to the concept used on axial dual spool engines. (I hope I'm using the correct terms)
The R-R Dart turboprop engine had a two-stage centrifugal compressor.
may I ask you how to calculate the composition chamber
like if the hot sections torbine diameter 18 inch will be 200 holse by size 0.6 inch per primary hole
make the answer example the composition chamber that in this vedio
Nothing you have written here makes any sense.
You need to read a few books to learn a few things, so you will know that your question is meaningless.
You will enjoy the learning process, I think.
Abdulmalik Alrogy - Do you mean combustion chamber? Or are you writing music in a very small room?
Technically that transport cart does have suspension. The side walls of the tires and the air pressure inside the tires are the suspension.
... Nit successfully picked.
AgentJayZ I have been reading "The New Science of Strong Materials" so I'm feeling a little smarter(ass) than normal.
Great video as always.
Quants had an oil supply pipe rupture and feed the engine with most likely an nice atomized spray of hp oil which caused the turbine disk to overspeed and catastrophically fail. I heard of diesel Engines burning their own oil even when fuel is removed.
No. Please see my answer to Juha Tuomala.
Why don't the inner combustion liners/liner burn up in all that heat and air?
...cooling air.
@@AgentJayZ That's impressive given the heat that's generated during combustion! Thanks!
Put cooling air in my channel search bar.
Parabéns cara tu és ucara
What, no mention of cartridge starters? Shame. Though I guess they're not used so much these days ("these days" being "in our lifetimes") and may never have been used in airliners, but still cool. Basically a big shotgun shell with no shot that pushes a piston to spin the gear the regular starter spins, rack-and-pinion style, also used on aircraft piston engines. OFC mainly used on fighters and bombers, that normally use ground power for starting in the conventional ways you explained, but might have to spin up eight J57s RIGHT NOW if war were declared.
Yes, we know all of that. Much discussed in videos... somewhere in the playlist I’ve created called YourQuestions Answered. It has a sort of index.
In an engine with multi spool architecture do the spools turn opposite directions to do away with the need for stators between the different spools? Don't respond if this has been covered already, or is just plane stupid.
Not stupid.
Some engines do use counter-rotating shafts.
Graham is more of an expert on that subject. He is our resident Rolls Royce design engineer.
... Hold for his contribution...
Thanks, AgentJayZ!
It's certainly not a stupid question: in fact; it's a great question. Years ago, at R-R Bristol, we ran a rig model of a two-stage, statorless, contra-rotating turbine, which eliminated the NGV row between the HP and LP blades - and it worked. I could be wrong, but I seem to recall seeing a cutaway GA of one of the latest US (military?) engines that had no NGV row between the HP and LP blades.
With R-R's current engine architecture, a statorless turbine isn't possible, because the IP NGVs in the Trent range and the LP NGVs in the EJ200 house structural 'spokes' and services for their turbine bearing housings. However, the EJ200 is contra-rotating and there is a performance advantage, because the low camber LP NGVs have lower aerodynamic losses that the equivalent high camber NGVs in a co-rotating turbine.
This is primarily the reason for the latest marks of Trent engine having a contra-rotating HP spool, so as to reduce the secondary flows and consequent aerodynamic losses in the IP NGVs.
grahamj9101 Thank you. That was quite informative.
If Combustion chamber more number in same size the thrust may change or increase or decrease. Please check it . Sir. My openion is thrust may increase.
Your comment makes no sense.
What am I supposed to check?
You have a great need for information and knowledge.
Have a look at my video about books. Search bar on channel page.
Little holes everywhere 😀
for implosions ,,, no disel fuel
It is suspected that the uncontained engine failure of National Airlines Flight 27 may have been a result of the crew playing around with engine throttle settings and causing the engines to overspeed.
en.wikipedia.org/wiki/National_Airlines_Flight_27
Would the Black Swan event of that Qantas flight QF32 years ago where they couldn't shut down an engine for two hours after it landed be classed as a "run away"? They ended up stopping the engine by swamping it with water from a couple of crash tenders. The accepted method of stopping a diesel run away is by the use of a flapper plate or a large enough rag to over/in the air inlet to starve oxygen.
+Reece Isaac
I would not call that a runaway.
Nor would I. The engine controls were just 'frozen'. That's not much different from having a jammed throttle on a diesel or petrol/gasoline engine - with the difference, of course, that, in a vehicle, they can be disconnected from the load.
PS I thought you were in Palm Springs CA, AgentJayZ? Merry Christmas and enjoy the warm weather. I'm off to Singapore (again) for a month at the end of January.
grahamj9101 will
How measure the jet engine power
Power = Torque * Rotational velocity. So, roughly speaking (I am just guessing here), they'd use a test stand that places a retarding torque (or 'load') on the engine, max out the throttle, find the torque that has the turbine can maintain its specified RPM at, and then you just calculate Torque * Rotational velocity, i.e., power. Obviously I'd also love to see specific details though.
Hi jay, stupid question from someone with no clue about engines. If radial compressors can do 900 percent compression and axial ones only about 10 and therefore need many stages, why are axial compressors used on big planes, while radial ones are more popular on model engines? Is the advantage of radials somehow lost when scaled up?
Several pages needed for an adequate answer.
All the books I recommend have them.
In my video about books. It's called Books.
Chip Detector?........or Chip Arrestor/Capture? Please do explain further if you will.
Chip detectors have a magnet that traps some of the ferrous metal chips, so that you can look at them.
Since you have a test cell and maybe a spare engine laying around. If I got a kick starter (pun intended) to supplied the garden hose of gas any you supplied the testicles to operate it, in the interest of science of course, could we find out if that would actually cause a run away?
I would have to ask the owners of the test cell. Any spare engines laying around are hulks, that will need about 50K of work at a minimum to get them to running shape.
Test cell fee is large, and does not include fuel or any labour to set the engine up.
If you can raise 100k US, and agree to cover any damages caused by catastrophic incidents, I'm sure your curiosity can be satisfied.
Ha! No need I was just pushing the funny. I've seen what happens when an axial flow steam turbine over speeds and its very bad, and they have very thick cases and no big exhaust hole at the back for parts to fly out of! Needless to say if one ever did run away you'd have heard about it!
That sounds like something for Mythbusters to do out in the middle of nowhere, maybe next to where they blew up the cement truck.
I think I've heard of an over speed when oil seals failed and before everything died from lubrication failure.
Robert Szasz You might be thinking of QF32 where an oil leak due to a parts error caused the turbine disk to overspeed. The damage to critical wiring in the wing then led to loss of command of the outboard engine which had to be shut down destructively with foam once they landed. It was running at the last commanded throttle setting.
www.atsb.gov.au/media/4173625/ao-2010-089_final.pdf
NoisyPlaces I think I heard of it happening on a test stand/demo turbine (for teaching purposes rather than power) I'm not surprised it has been documented at least once. It's a very very rare failure mode though.
27:20 Here's what I found about those three things in Solos pocket: movies.stackexchange.com/questions/52459/what-are-these-cartridges-that-many-characters-have-in-the-star-wars-movies
Apparently, they're detonators..
Amazing. I actually (foolishly) thought I was the only weirdo thinking about such a small detail in the movie...
@@AgentJayZ I think it's weird that everyone in Starwars is apparently just carrying around multiple detonators on a daily basis... lol.
I picture before any of the guys leave for the day, the wives are like "Don't forget your detonators, honey! You left 2 out of 3 of them here yesterday - remember, you'd rather have it and not need it than need it and not have it! Smooches."
Little holes. Hmmm