Off Topic. As hydralic systems start to take a load and pressure builds up what is causing the high pitch whine? is it tiny leaks in the pump like a whistle, pump cavitation or what? All makes seem to have a similar high pitched whine when loaded. I am talking about presses, compactors etc.
Bil lD.
Not my personal bag. An expert should be along to discuss the effects of pumps, turbulence, friction, directional changes (an elbow introduces noise), efficiency and speed of sound in a pressurized fluid, etc.
But I CAN share that it is not just an annoying trait.
Sounds generated by, or carried by, fluids can be seriously USEFUL as well.
Old Day Job (Esterline Medical) got curious as to why we had orders for multiple THOUSANDS of our patented "bone vibrator" AKA inertial transducers meant for hearing aids that were not going to folks with hearing problems.
Lots of air miles, rental cars, autographed photos from Jacques Costeau (Air Liquide owned U.S. Divers), Bev Morgan (Kirby-Morgan "Band Mask"), Jim Helle (Hellephone), and a slew of major oil companies as preferred not to be identified...
And... a unit we had built to be "deaf kid abuse proof" had been put to use
miles down monitoring flow in seabed oil production rigs by the sound, telemetered up-cable to spectrum-analyzer display screens.
Did that valve open, as commanded? If so, how wide? Does that flow sound the same as what is on-record?. etc.
The other players were using them for diver-to-diver, and diver to surface audio communications over a carrier. 40 Khz or so, with Barium Titanate or Lead Zirconate Titanate piezo transducers ..IF.. I recall correctly. 1972-73, so no certainty of that.
Irony? The transducer product line was later hived-off and basically outlived the original hearing aid side of the firm. At least with any claim to "continuity" about it.
Next time that noise bugs you?
Just think how much less safe, and how much more expensive, our petro products might be if there was no sound to use for monitoring.