The microscopes sit on air-tables, which have inflatable components so that the support between them and the ground is not rigid. It damps vibration.
The cow is optional and we plan to evaluate the system cowless before we make any acquisition commitment. After all, we don't yet know how powerful a cow we'll need.
My compressor is bigger than your compressor. I just bought the 40HP one to drive my industrial noise machine. My industrial noise machine is a siren in the compressor airflow with a combustor amplifier on the back end. It'll do about 140dB.
I can't see where the flames come into (or out of) that one, and it's the burning bit that makes it: a) loud, no really, very very loud indeed, and b)interesting. :)
It works by modulating the air flow but not the fuel, so that the heat release of the mixture can be made to vary. Slow the air down a touch and the Fuel Air Ratio (FAR) goes up, the heat release increases and then the the resulting pressure wave from the thermal expansion blasts out the exhaust. Tune the siren in the air flow to get different frequencies. In feedback mode, the pressure wave will feed back up the inlet and slow the air further, giving a bigger increase in FAR and hence bigger pressure waves. The system then collapses and repeats. This gets so noisy that it used to make all the hard drives in the lab vibrate so much that they wouldn't write to disk......
It's really for studying combustion oscillation and vortex shedding processes, but it does sound good. :)
That sounds much like something Daedalus suggested . . . many many years ago. how long have people been building and using these things? And do Einstürzende Neubauten know about them?
Only in the last 10 years or so as lean burn gas turbines starting having oscillation problems. At least, that's as far as I know. We used to have one that ran on kerosene, but I stripped it and modified for methane. Soon to be upgraded to run on methane-hydrogen mix.
I don't know if Einstürzende know about them, but I'm sure they should.
Ten years? It might actually be another Daedalus invention, then, because I'm sure I read about it in his column a while longer ago than that. Apparently about 17% of his suggestions end up in serious R&D.
As far as I know it was more a solution for diagnostic to control the vortex shedding and oscillations than an invention for combustors as such. Gas turbine combustors will behave like this simply when run lean. The research step was simply to lock in the experimental frequency to enable easy imaging of the oscillation process.
Noise is one of the major nuisances of modern life. Yet the usual sound-absorbing materials are purely passive, and can never damp it out completely. Daedalus now proposes an active absorber, inspired by the observation in a chemical textbook that the carbon monoxide flame "gives a curious impression of silence". Carbon monoxide, he notes, burns with a reduction in the number of gas molecules. If, like most gas reactions, the burning speeds up with pressure, then a sonic pressure-peak will deplete the gas of molecules at an enhanced rate, and damp itself out. Conversely, when the pressure is low, the depletion slows down. So the flame absorbs the sound. Furthermore, certain flames are extremely sensitive to sound. They were used as acoustic detectors in pre-microphone days. Even a weak sound changed their combustion regime very visibly.
So Daedalus is inventing quiet flame technology. He is devising nozzles and flame-surrounds that optimize this sound-damping effect. He hopes to perfect a gas burner whose nonlinear reaction regime overreacts to sound, and thus absorbs it perfectly. A street lamp that absorbed traffic noise would be welcome on busy roads; victims of aircraft noise or pop-crazed neighbours would love a gas fire that gave out quiet as well as heat.
Even so, nobody would want to keep a fire burning on a hot day, merely to keep the noise down. So Daedalus is taking the argument further. When iron rusts, for example, gas molecules are completely absorbed into a solid. DREADCO's chemists are now studying the oxidation of iron alloys, as well as yellow phosphorus, aluminium amalgam and even lithium (which absorbs nitrogen as well). They are seeking pressure-sensitive reaction regimes with strong nonlinearity, or even a pressure threshold. Their goal is a surface that rusts or tarnishes with total absorption of sound. Ideally it should change colour during the reaction. When fully reacted, it could be regenerated, perhaps by reduction with hydrogen.
This novel decor will be very expensive at first, and will be aimed at acoustics laboratories and recording studios. Gradually it should spread to the more opulent homes, offices and public buildings. A personal version in earmuff form would be widely welcomed; not only for the quiet in which it wrapped the wearer, but for the pleasing warmth released by its slow sonic oxidation.
Hmm. Not quite quiet though, as the heat release is still going to dominate the reduction in the number of molecules and give you an expansion process. You also need to take into account that you need some hydrogen somewhere in the system to make CO burn. High humidity air is usually enough. The idea of an endothermic and reducing reaction would work better I think.
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timeasmymeasure
no subject
Date: 2005-02-08 03:50 pm (UTC)no subject
Date: 2005-02-08 03:52 pm (UTC)no subject
Date: 2005-02-08 04:57 pm (UTC)no subject
Date: 2005-02-08 03:51 pm (UTC)no subject
Date: 2005-02-08 03:54 pm (UTC)The cow is optional and we plan to evaluate the system cowless before we make any acquisition commitment. After all, we don't yet know how powerful a cow we'll need.
no subject
Date: 2005-02-08 05:50 pm (UTC)no subject
Date: 2005-02-08 06:46 pm (UTC)no subject
Date: 2005-02-09 11:03 am (UTC)I can't see where the flames come into (or out of) that one, and it's the burning bit that makes it: a) loud, no really, very very loud indeed, and b)interesting. :)
no subject
Date: 2005-02-08 08:25 pm (UTC)no subject
Date: 2005-02-09 10:53 am (UTC)It's really for studying combustion oscillation and vortex shedding processes, but it does sound good. :)
no subject
Date: 2005-02-09 10:57 am (UTC)no subject
Date: 2005-02-09 11:07 am (UTC)I don't know if Einstürzende know about them, but I'm sure they should.
no subject
Date: 2005-02-09 11:11 am (UTC)no subject
Date: 2005-02-09 12:10 pm (UTC)no subject
Date: 2005-02-09 11:35 am (UTC)no subject
Date: 2005-02-09 11:40 am (UTC)Noise is one of the major nuisances of modern life. Yet the usual sound-absorbing materials are purely passive, and can never damp it out completely. Daedalus now proposes an active absorber, inspired by the observation in a chemical textbook that the carbon monoxide flame "gives a curious impression of silence". Carbon monoxide, he notes, burns with a reduction in the number of gas molecules. If, like most gas reactions, the burning speeds up with pressure, then a sonic pressure-peak will deplete the gas of molecules at an enhanced rate, and damp itself out. Conversely, when the pressure is low, the depletion slows down. So the flame absorbs the sound. Furthermore, certain flames are extremely sensitive to sound. They were used as acoustic detectors in pre-microphone days. Even a weak sound changed their combustion regime very visibly.
So Daedalus is inventing quiet flame technology. He is devising nozzles and flame-surrounds that optimize this sound-damping effect. He hopes to perfect a gas burner whose nonlinear reaction regime overreacts to sound, and thus absorbs it perfectly. A street lamp that absorbed traffic noise would be welcome on busy roads; victims of aircraft noise or pop-crazed neighbours would love a gas fire that gave out quiet as well as heat.
Even so, nobody would want to keep a fire burning on a hot day, merely to keep the noise down. So Daedalus is taking the argument further. When iron rusts, for example, gas molecules are completely absorbed into a solid. DREADCO's chemists are now studying the oxidation of iron alloys, as well as yellow phosphorus, aluminium amalgam and even lithium (which absorbs nitrogen as well). They are seeking pressure-sensitive reaction regimes with strong nonlinearity, or even a pressure threshold. Their goal is a surface that rusts or tarnishes with total absorption of sound. Ideally it should change colour during the reaction. When fully reacted, it could be regenerated, perhaps by reduction with hydrogen.
This novel decor will be very expensive at first, and will be aimed at acoustics laboratories and recording studios. Gradually it should spread to the more opulent homes, offices and public buildings. A personal version in earmuff form would be widely welcomed; not only for the quiet in which it wrapped the wearer, but for the pleasing warmth released by its slow sonic oxidation.
no subject
Date: 2005-02-09 12:04 pm (UTC)