RR Resonance Very Loud!

Olympus from light-off up to idle making very loud low frequency sound.

This is the only footage (so far) of the famous dancing pipe wrench.
It is made of aluminum, but it is a 24 incher.
It stops rattling when I grab it.
Then you get to hear the engine rev up past the range of resonance, clear out, and start to really scream.

Funny, at the end of this clip, the Olympus is just above idle.

Category:

Autos & Vehicles

Tags:

• Rolls
• Royce
• Olympus
• jet
• S&S
• Maddex
• turbine
• Vulcan
• resonance
• engine
• concorde
• power

[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.

[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 !

[PhalkenDrift]

now what if this was a vacuum cleaner

[oakmanrob]

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

[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.

[JetMech72]

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

Cool vid.

[cheetawolf]

this is the ultimate bass tester...