Big fan with a quick question. Since these are aero-derivative engines, is the gearbox used for power takeoff? What changes, if any, are made to the drivetrain?
@rschulemann The radial drive shaft is ised to supply power to the gearbox to drive the accessories. The difference in industrial engines is that there are less accessories driven.
This engine produces about 10 thousand Hp.. in the form of hot, high velocity gases exiting the engine... to be sent through a separate power turbine, which then turns a shaft.
Thanks AgentJayZ, your videos are amazing... I'm working on a power plant where we have 190MW gas turbines for electric generation, once we got problems with icing in the two first stages of the axial flow compressor, apparently the ice grew up as much as it could touch the rotor blade tip at 3600RPMs deforming it, then the discharge pressure went down and so did the power output... I would like to know if you had have same problem in aircraft engines?
@elcuervo1984 Occasionally we experience icing of the inlet during our testing. I've only seen ice build up on the leading edges of the struts in the front frame. This happens at just above freezing when the humidity is high.
On days like that when we are having a test, we place one person where they can watch for ice in the inlet, and if they see it, we stop the test. The reason is the engines we work on are not equipped with anti-icing capability.
I'm sure there's a world of engineering into fuel nozzles, shaping of the combustors and even more onto fuel mappings. But it is funny that it kind of works like a tap: if you want more, just open the tap more :) Any clues on a typical mapping of power vs fuel pressure? is it even close to proportional or much more esoteric?
@pjvenda I've just been doing some reading on combustor design, and as always, it's a bit more complicated than I present in this quick, easy video.
Although there is no control for fuel-air ratio in a jet engine, the ratio in the combustion zone does change on its own. Because of the interaction between fuel spray patterns at differing fuel pressures, and air density at different compressor discharge pressures, the air-fuel ratio changes from lean at start to rich at full power.
@AgentJayZ which gives jet engine more efficiency, lean fuel or rich fuel mix if ur at optimum power or cruise power or wat ever u guys call it....? ?
and generally the air/fuel ratio depends on the bypass ratio or something?
Another great video.I wish you had been around 10 years ago when i was buying an engine to build a jet dragster for 1/4 mile and exhibition work.I really wanted a J-85 but they were beyond our budget as the cheapest one i could find was $22,000 US so i had to choose between RR Viper 500 or 600 series or P&W J-60.I decided on the JT12 as it looks a lot nicer and was lighter than the Viper.I managed to find 1 for $10,000 i will tell you more next time. Cheers
@AgentJayZ I get positively giddy whenever you post a new video!, absolutely fantastic informative and interesting. Really makes me want to work with this.
Hello Jay, I can't get enough of these videos, there always so interesting to watch. I should have been a jet engine mechanic (maybe in my next life). Quick question, is the purpose of the VSV's to control the air/fuel mixture for optimal engine eficentcy or does it serve some other function?
@joelvh1 The only thing controlling the air fuel mixture is how much fuel is sprayed in. The mixture is always the same, because there is always more than enough air. That's the whole point of this video.
There is no such thing as mixture control with turbine engines.
The VSV's manage the direction of incoming air so as to avoid having the compressor blades experience aerodynamic stall.
@AgentJayZ Cool, I just learned something new again. I was under the impression that the VSV's had something to do with the air/fuel mixture. Thank you for explaining that.
Jay thanks for another brilliant video. Another question if you dont mind not really linked to this video. How does the lubrication system work? Is there an oil sump like a car and what sort of oil does something like this require, im guessing an ester synthetic oil? Is there a way of checking the oil level? Sorry if these questions sound dumb!
@xxJohn1977xx We are using Mobil Jet II synthetic turbine engine oil. These engines are dry sump. Each bearing has it's own sump that is emptied by its own scavenge section of the main oil pump. That pump has three sections: one pressure element and two scavenge. There is also a separate scavenge pump for the gearbox.
The oil supply in out tests is that silver box you see under the engine. Most installations have a large remote reservoir holding a hundred gallons or so.
I could have sworn I have seen some whittle era designs that used evaporator systems to counter the cost/complexity of a high pressure fuel system. I do know that is how most of the small RC turbines deliver fuel.
Regardless it isn't horribly efficient or clean burning, thus the high pressure systems for today.
Propane is easier to burn than jet fuel, mainly because the gaseous fuel mixes with air easier and has a higher volatility than kero type fuels. In fact, jp5, jp8, and other similar types of jet fuel actually are very hard to light (even with an open flame as compared to other fuels) especially in a fuel spill type of situation, thus why they are a preferred fuel to use. In even older styles of jet engines the fuel was actually put through an evaporator in the combu
@ProjectWolfDragon This is all true, except the last bit. The only engines I know of that use some sort of heat-transfer evaporation feature for vaporizing fuel as it is fed to the combustor are the Tubomeca helicopter engines, and the Orenda Iroquois.
All other large engines spray the fuel directly into the burning zone. Some of the most modern airliner engines incorporate "pre-mixing" zones for air and fuel, but even the manufacturers don't call them evaporators or vaporizers.
@Morkvonork Many of the engines we work on are fuelled with natural gas, and those ones we test with propane. This engine runs on jet fuel, so it will be tested with Jet A.
In the clip discussing start up procedure, you said that the engine is first spooled up, the ignitor is started and only after then is the fuel added, so that the fuel does not collect and cause a bang. How long does it take the fire to transverse through the ears? Does the can opposite the ignitor always get a more painful ignition due to fuel being sprayed into the can before the fire lights it up?
@krbruner The flame travels to all the other combustors essentially instantly. If there was any banging or roughness in starting, these engines would have an ignitor for every fuel nozzle.
Yes! More pressure => more fuel flow => more RPM's => faster turning fuel pump => more pressure ....... on and on, accelerating the engine until it explodes ---- or until a valve "leaks" fuel causing the pressure to stabilize at some level. Simple! Ha, once you "get it". Took me 10 years!
I'm controlling my turbine with a little brass valve $1.75 from ACE hardware.
Hello and thanks again AgentJayZ. I too learn a lot from your videos.
It sounded like you said that only some of the combustors have ignitors and that the hot gasses communicate via the interconnectors so do the ignitors need to run constantly or once the fire is burning in the combustors, they stay lit as long as there is fuel?
A cool view you gave us of that nozzel being fitted into position.
@mwroush Once the fire is lit, it stays lit. For safety, during takeoff, airliners keep the ignition sparking just in the one-in-a-million chance the flame might be lost. Otherwise, when you see a jet flying overhead, the ignitors are turned off.
If you watch my test videos, the ignitors are turned off before the start cart is shut down. They are only used for a few seconds to start combustion in the engine.
Why dirty ignitors? Usually dirt remains on the burner ... Ignitors for this engine working constantly? Or this the engine running on liquid fuel. I guess I know too little English. Very sorry for ...
Big fan with a quick question. Since these are aero-derivative engines, is the gearbox used for power takeoff? What changes, if any, are made to the drivetrain?
rschulemann 1 month ago
@rschulemann The radial drive shaft is ised to supply power to the gearbox to drive the accessories. The difference in industrial engines is that there are less accessories driven.
This engine produces about 10 thousand Hp.. in the form of hot, high velocity gases exiting the engine... to be sent through a separate power turbine, which then turns a shaft.
AgentJayZ 1 month ago
Very interesting thank you!
buffplums 2 months ago
Thanks AgentJayZ, your videos are amazing... I'm working on a power plant where we have 190MW gas turbines for electric generation, once we got problems with icing in the two first stages of the axial flow compressor, apparently the ice grew up as much as it could touch the rotor blade tip at 3600RPMs deforming it, then the discharge pressure went down and so did the power output... I would like to know if you had have same problem in aircraft engines?
elcuervo1984 2 months ago
@elcuervo1984 Occasionally we experience icing of the inlet during our testing. I've only seen ice build up on the leading edges of the struts in the front frame. This happens at just above freezing when the humidity is high.
On days like that when we are having a test, we place one person where they can watch for ice in the inlet, and if they see it, we stop the test. The reason is the engines we work on are not equipped with anti-icing capability.
AgentJayZ 2 months ago
I'm sure there's a world of engineering into fuel nozzles, shaping of the combustors and even more onto fuel mappings. But it is funny that it kind of works like a tap: if you want more, just open the tap more :) Any clues on a typical mapping of power vs fuel pressure? is it even close to proportional or much more esoteric?
pjvenda 3 months ago
@pjvenda I've just been doing some reading on combustor design, and as always, it's a bit more complicated than I present in this quick, easy video.
Although there is no control for fuel-air ratio in a jet engine, the ratio in the combustion zone does change on its own. Because of the interaction between fuel spray patterns at differing fuel pressures, and air density at different compressor discharge pressures, the air-fuel ratio changes from lean at start to rich at full power.
AgentJayZ 2 months ago
@AgentJayZ which gives jet engine more efficiency, lean fuel or rich fuel mix if ur at optimum power or cruise power or wat ever u guys call it....? ?
and generally the air/fuel ratio depends on the bypass ratio or something?
911mastermind 2 months ago
Thanks for the explanation. it answered most of my questions.
117nathanmyers 3 months ago
u r an inspiration to me and others!
prandtl002 3 months ago
Another great video.I wish you had been around 10 years ago when i was buying an engine to build a jet dragster for 1/4 mile and exhibition work.I really wanted a J-85 but they were beyond our budget as the cheapest one i could find was $22,000 US so i had to choose between RR Viper 500 or 600 series or P&W J-60.I decided on the JT12 as it looks a lot nicer and was lighter than the Viper.I managed to find 1 for $10,000 i will tell you more next time. Cheers
topdoorslammer666 3 months ago
These are the best videos on the internet.
alanhigh 3 months ago 12
@alanhigh Thanks! ... I don't think they're anywhere near the best, but I hope to keep making them better than I did before.
AgentJayZ 3 months ago
@AgentJayZ I get positively giddy whenever you post a new video!, absolutely fantastic informative and interesting. Really makes me want to work with this.
Tomasu321 3 months ago
@alanhigh For the subject they cover, I have to agree about them being the best videos on the internet. Can't compare to cute kitten videos though.
oisiaa 3 months ago
@alanhigh yeh excellent channel.
cheers
plasticspastic201 3 months ago
Hello Jay, I can't get enough of these videos, there always so interesting to watch. I should have been a jet engine mechanic (maybe in my next life). Quick question, is the purpose of the VSV's to control the air/fuel mixture for optimal engine eficentcy or does it serve some other function?
joelvh1 3 months ago
@joelvh1 The only thing controlling the air fuel mixture is how much fuel is sprayed in. The mixture is always the same, because there is always more than enough air. That's the whole point of this video.
There is no such thing as mixture control with turbine engines.
The VSV's manage the direction of incoming air so as to avoid having the compressor blades experience aerodynamic stall.
AgentJayZ 3 months ago
@AgentJayZ Cool, I just learned something new again. I was under the impression that the VSV's had something to do with the air/fuel mixture. Thank you for explaining that.
joelvh1 3 months ago
Jay thanks for another brilliant video. Another question if you dont mind not really linked to this video. How does the lubrication system work? Is there an oil sump like a car and what sort of oil does something like this require, im guessing an ester synthetic oil? Is there a way of checking the oil level? Sorry if these questions sound dumb!
Thanks John.
xxJohn1977xx 3 months ago
@xxJohn1977xx We are using Mobil Jet II synthetic turbine engine oil. These engines are dry sump. Each bearing has it's own sump that is emptied by its own scavenge section of the main oil pump. That pump has three sections: one pressure element and two scavenge. There is also a separate scavenge pump for the gearbox.
The oil supply in out tests is that silver box you see under the engine. Most installations have a large remote reservoir holding a hundred gallons or so.
AgentJayZ 3 months ago
@AgentJayZ Thanks Jay, would there be any chance you could maybe do a video showing the lube system?
Regards, John
xxJohn1977xx 3 months ago
@AgentJayZ
I could have sworn I have seen some whittle era designs that used evaporator systems to counter the cost/complexity of a high pressure fuel system. I do know that is how most of the small RC turbines deliver fuel.
Regardless it isn't horribly efficient or clean burning, thus the high pressure systems for today.
ProjectWolfDragon 3 months ago
aah man jay thank you so much buddy, learned a lot! :)
"aah lets try this again"
ehehehe
M3G4G0TH 3 months ago
@Morkvonork
@TheElectricnoob
Propane is easier to burn than jet fuel, mainly because the gaseous fuel mixes with air easier and has a higher volatility than kero type fuels. In fact, jp5, jp8, and other similar types of jet fuel actually are very hard to light (even with an open flame as compared to other fuels) especially in a fuel spill type of situation, thus why they are a preferred fuel to use. In even older styles of jet engines the fuel was actually put through an evaporator in the combu
ProjectWolfDragon 3 months ago
@ProjectWolfDragon This is all true, except the last bit. The only engines I know of that use some sort of heat-transfer evaporation feature for vaporizing fuel as it is fed to the combustor are the Tubomeca helicopter engines, and the Orenda Iroquois.
All other large engines spray the fuel directly into the burning zone. Some of the most modern airliner engines incorporate "pre-mixing" zones for air and fuel, but even the manufacturers don't call them evaporators or vaporizers.
AgentJayZ 3 months ago
You guys in the shop should have a little competition to see who can make the most powerful engine out of a car turbocharger :) I reckon you'd win.
FrontSideBus 3 months ago
Thanks for videos, great job =)
degl1234 3 months ago
why do you test the engines with propane when they usually use kerosene?
Morkvonork 3 months ago
@Morkvonork LPG is cheaper than kerosene i reckon.
TheElectricnoob 3 months ago
@Morkvonork Many of the engines we work on are fuelled with natural gas, and those ones we test with propane. This engine runs on jet fuel, so it will be tested with Jet A.
AgentJayZ 3 months ago
Thanks. We have for our engines turn off the ignitors at n1 = 3000 rpm. But... why did ignitors dirty? A burners is all right...
MrChibass1 3 months ago
In the clip discussing start up procedure, you said that the engine is first spooled up, the ignitor is started and only after then is the fuel added, so that the fuel does not collect and cause a bang. How long does it take the fire to transverse through the ears? Does the can opposite the ignitor always get a more painful ignition due to fuel being sprayed into the can before the fire lights it up?
krbruner 3 months ago
@krbruner The flame travels to all the other combustors essentially instantly. If there was any banging or roughness in starting, these engines would have an ignitor for every fuel nozzle.
AgentJayZ 3 months ago
Another great vid Jay. Your editing keeps getting better. Cheers.
matube73 3 months ago
Yes! More pressure => more fuel flow => more RPM's => faster turning fuel pump => more pressure ....... on and on, accelerating the engine until it explodes ---- or until a valve "leaks" fuel causing the pressure to stabilize at some level. Simple! Ha, once you "get it". Took me 10 years!
I'm controlling my turbine with a little brass valve $1.75 from ACE hardware.
LarryCanFly 3 months ago
Hello and thanks again AgentJayZ. I too learn a lot from your videos.
It sounded like you said that only some of the combustors have ignitors and that the hot gasses communicate via the interconnectors so do the ignitors need to run constantly or once the fire is burning in the combustors, they stay lit as long as there is fuel?
A cool view you gave us of that nozzel being fitted into position.
mwroush 3 months ago
@mwroush Once the fire is lit, it stays lit. For safety, during takeoff, airliners keep the ignition sparking just in the one-in-a-million chance the flame might be lost. Otherwise, when you see a jet flying overhead, the ignitors are turned off.
If you watch my test videos, the ignitors are turned off before the start cart is shut down. They are only used for a few seconds to start combustion in the engine.
AgentJayZ 3 months ago
AgentJayZ is the greatest turbine teacher.
LarryCanFly 3 months ago 11
Why dirty ignitors? Usually dirt remains on the burner ... Ignitors for this engine working constantly? Or this the engine running on liquid fuel. I guess I know too little English. Very sorry for ...
MrChibass1 3 months ago
Thanks Jay! Awesome Video! Thanks For A Great Education!
poppopscarvinshop 3 months ago
Loved the video - only complaint is I now have to wait a week for the next one:). Thanks for the great videos.
hqa467 3 months ago 4
I always learn something new from your videos :D Keep up the good work.
ScottieNiven 3 months ago
1st comment o_O
TehVag 3 months ago