supersonic flow
supersonic flow
(OP)
Hello everyone. I am attempting to build a small vortex tube for spot cooling of milling operations. I relize that vortex tubes are avalible comercialy for under $150 but want to try to build one myself just out of curiosity. A vortex tube employes a high volocity gas jet that creates a vortex which in turn causes denser cold air to separate from less dense hot air.
http://en.wikipedia.org/wiki/Vortex_tube
I want to use a converging diverging nozzle to create this high volocity gas jet. It would be conveniant to use shop air compressor with max psi of 120psi. I know that for a converging diverging nozzle to work the gas volocity must be Mach 1 at the throat to be further accelerated by the diverging section. So is it possible to create a sonic flow with a converging section and 120 psi compresed air? Does a decrease in orfice diameter cause a increase in velocity if presure is held constant? Does anyone know of any equations that would apply here? Any info will be gladly appreciated.
Thanks everyone for your time.
Jslade
http://en.wikipedia.org/wiki/Vortex_tube
I want to use a converging diverging nozzle to create this high volocity gas jet. It would be conveniant to use shop air compressor with max psi of 120psi. I know that for a converging diverging nozzle to work the gas volocity must be Mach 1 at the throat to be further accelerated by the diverging section. So is it possible to create a sonic flow with a converging section and 120 psi compresed air? Does a decrease in orfice diameter cause a increase in velocity if presure is held constant? Does anyone know of any equations that would apply here? Any info will be gladly appreciated.
Thanks everyone for your time.
Jslade





RE: supersonic flow
http://www.engineering-4e.com/calc4.htm
http://www.engineering-4e.com/calc5.htm
I do hope that the above URLs can help you with some of your design issues and provide you with requested technical background information and engineering equations.
Good luck!
http://www.engineering-4e.com
RE: supersonic flow
I'm just not sure what you're gaining by going that fast. The device heats/cools the air due to heat transfer facilitated by the conservation of angular momentum between the inner (cooling) stream and the outer (heating) stream. By speeding up the outer stream aren't you decreasing the amount of time that this heat transfer can act? I've seen Ranke Hilsche Vortex Tubes with back pressure regulators on the outlet of the cold side to increase the heat transfer time, seems like you are going in the opposite direction.
Good luck with this. I've always been interested in a device that appears to violate the laws of thermodynamics (but doesn't really) and have designed a couple of odd applications to use them that haven't taken off yet (and probably never will).
David
RE: supersonic flow
There is no generally accepted theory on how vortex tobes work but air density is not one of the factor. My personal conclusion that the votex tube separates molecules where the randon thermal motion is in line with the airflow (high-velocity, hot molecules) from molecules where the random thermal motion is opposite to the air flow (slower-velocity, cool molecules). The spinning can generate tens of thousands of G's as I recall.
RE: supersonic flow
the valve in the main discharge adjust the temperature
doesn't violate the laws of thermowell nor does it centrifuge the hot cold fractions, but they are neat
RE: supersonic flow
The following site shows ideas to build the contraption:
RE: supersonic flow
Thanks everyone
Jslade
RE: supersonic flow
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There are some very knowledgeable people who are willing to go an extra mile when providing requested input ...
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