RR Resonance Very Loud!

[oakmanrob]

What about intake pressure?

[AgentJayZ]

@oakmanrob Intake pressure is ambient air pressure minus screen loss minus bellmouth depression, which are how hard it is to suck air through the screeen and intake flare... very minor but still significant when you're pulling 150 lbs per second of air or more.

[oakmanrob]

Is the low frequency resonance from back pressure built up at low rpm? or is there some other cause?

[AgentJayZ]

@oakmanrob There is a resistance caused by the reduced exhaust orifice, but it causes a pressure rise in the exhaust duct as engine airflow increases. I think the low velocity airstream at startup causes the engine/exhaust duct combination to act as a resonator, and the flame trailing edge may also fluctuate, contibuting to the sound.

We have a pressure sensor in the exhaust duct, and at startup, its reading is no different from ambient.

[oakmanrob]

Is the low frequency resonance from back pressure built up at low rpm? or is there some other cause?

[JetMech72]

Wow. When those ignitors hit, it was like listening to a bee farting in a coke bottle.

Cool vid.

[MusicMan20061210]

I love it that you put this up on YT. I like learning about all kinds of technology and this is about the only chance to experience this in action.

Amazing engines.

Thank you!

[AgentJayZ]

@MusicMan20061210 Thank you. The reasons you like these videos are the smae reasons I put them up.

In late 06, I could not find any close-up information or images of running jet engines with any kind of image quality.

I am trying to supply some for the people who aren't lucky enough to be able to climb all over them and get inside them...

I need suggestions for new subjects !

[exmarine66]

@AgentJayZ Yup. Great videos indeed. I'm about to get certified as an A & P mechanic. Can't see engines any other way, for now.

[cheetawolf]

this is the ultimate bass tester...

[ratty860997]

Is that the same engine thats in the Vulcan?

[AgentJayZ]

@ratty860997 Very closely related.

[fallingwater]

Is it running off that small propane tank at the right of the engine, or is the tank there for some other purpose?

[AgentJayZ]

@fallingwater A 6, 000L tank is out of sight.

The propane tank is actually filled with air at 120 psi to power the fuel cutoff switch.

[killman369547]

how much do these cost

[bazzathemammoth]

that was an epic resonance!!!!!!

[NoWattz]

sounds like about 28Hz. I can't imagine what kind of decibel level. To make a wrench bounce around like that, i'd imagine it's pretty significant level.

[badalice07]

What kind of RPMs are we talking about here?

[AgentJayZ]

It's a two-shaft engine.

The larger, Low Pressure system gets to about 4000 rpm max, and the HP system gets to 8000 max.

Watch my latest Olympus video:

" Olympus Gas Turbine Engine Test... LOUD "

and you will see some views of the control room screen showing the sensors we monitor during testing, including rpm

[GenXCypher]

Thanks for this :D

[GenXCypher]

quick question... at about 0:35 to 0:37 the engine makes a sudden drop in sound... what is this? what causes it?

[AgentJayZ]

I'm not sure what that was, but it could have been me moving a tool or something.

At 0:27 is when the engine actually starts burning fuel.

[PhalkenDrift]

now what if this was a vacuum cleaner

[Wolfie123123]

You'd wreck it if you stuck stuff in that intake.

[MercedesSLK350V6]

Well if it was a vacuum cleaner it would be one heck of a vacuum cleaner!

[teletubbykiller23]

@PhalkenDrift IT MAY LOOK TOUGH ENOUGH TO VACCUM UP STUFF BUT YOU'D DESTROY THE ENGINE IF IT WAS TAKING THE ABUSE OF A VACCUM CLEANER'S IMPELLER A VACCUM CLEANER IS DESIGNED TO CLEAN A TURBOJET IS DESIGNED TO BE A ENGINE

[1metiz]

Thats a cool video man, thanks! could you upload or link to a RAW version of this, without the cuts? I'd realy like to hear one of these engines rev up from the very start.

[AgentJayZ]

As a matter of fact, I do have a video like you describe.

It's called Jet Power: very loud.

It is the unedited throttle up of this engine from just after start to all the fuel we can give it.

Thanks for the interest!

[futuresoldier7]

i have a wierd question but i am very curious to know, how much gallons of fuel does this thing use.. er in whatever term they use, seconds? minutes? hours?

[AgentJayZ]

We don't measure fuel consumption normally, because it is not really a concern for the customer.

The only engine we did measure it for was a kerosene-fuelled J79, which is about 2/3 as powerful as this Olympus.

That engine, which is in my video "fighter jet afterburner test" used 37 gallons per minute at full power, and 87 gpm at full power with afterburner.

[sammo303]

Hey there, couple of questions for you:

- What fuel do you run these engines with, Kerosene?

- Are these operated with a manual throttle lever?

- The Olympus engines are getting a bit long in the tooth now, is excessive vibration often an issue even after overhaul?

- Are the IGVs coated in some sort of copper coating?

- Are these for aero or industrial use?

Thanks for the interesting video!

[AgentJayZ]

We test our engines on gaseous propane or on kerosene, depending on what the engine will use in service.

The fuel is metered using an electromechanical valve which is remote controlled by a manual lever in the booth.

Our engines are balanced to less than half the manufacturers allowed tolerance. When they pass our test run, we have never had one develop vibration problems.

[AgentJayZ]

The IGVs do appear to have a copper coating, perhaps to facilitate heat transfer from the hot air blown through them by the anti-icing system.

This is an industrial Olympus, used to generate electric power from the burning of natural gas for fuel.

In this video the engine is fuelled with propane.

Thanks for the interest!

[jakerzpazio]

I thought you would have to get it through resonance asap ?

[AgentJayZ]

Yes, it is not the healthiest thing for the jetpipe, and here in this test we do increase the revs as quickly as we prudently can.

The Olympus has poor throttle response at or below idle.

It is also a test of a newly rebuilt engine, so every throttle advance is a new adventure.

[seaniam81]

What's the tank of propane for? I've seen it in a bunch of vids

[AgentJayZ]

It's actually filled with 120psi air, and is used as the power source for the emergency fuel shut off valve.

So no matter what kind of power failure we may have... we can always shut down the engine.

It's at every test, and checked before every run.

[aruju01]

Must make your fillings rattle too....

Cool vid, keep 'em coming.

Avon when?