Supersonic Air Flow?

I wouldn't think so as it will only be pushed by 1 bar.
I would think a positive pressure (say a high pressure pump or an explosion) could make it exceed the speed of sound.
Del

There was such a device in university.

It was dismantled, but as I remember, had a 75Hp motor, canisters and a venturi.

MACH speeds were not produced for a long period, only a a pew seconds.

Depends on the velocity of reference, and of course, also depends on the reference temperature. I used to make such calculations many years ago regarding catastrophic impact assessment with rupture of pressure relieve valves.

If the reference velocity is just right then the frictional dissipation of energy that heats up the gases at some point begin to accelerate the gas and thereby causing further heating of the gas, and anyway you get the picture. The final form of the flow depends on the starting conditions and yes you are correct the pipe dimensions also impacts the results but that is factored in through the reference velocity; however, because of the contribution of the frictional dissipative heating, the roughness of the pipe wall is quite critical in these calculations.

I would think that a good reference point to start any computational research would be the specification of the maximum load of the pressure relieve valve before rupture.

In order to induce flow, a pressure difference must exist (you are supplying with vacuum zone). As pressure drops, density drops and "speed of sound" increases. It may be a curious property of air that you cannot suck it fast enough to overcome the increasing speed of sound caused by the pressure and density drop induced by the very sucking you generate in the first place. Just a random thought - I have no data or calculations to support one way or the other.

You can have a "blow-down" supersonic tunnel, but not a "suck-down". I suppose it could work very briefly, but the pressure equalization would occur too quickly for useful data to be taken.

Hi All:

If the vacuum is great enough to cause the flow to go sonic would not the pipe choke the flow of air and limit it to the speed of sound just like a nozzle?

GOD'S BLESSINGS

Bill

There are some great references to super/hyper sonic wind tunnels on wikipedia. You might want to especially look into Ludwieg tube. The citation on Wiki should answer your questions.

Variations of these tunnels have been used at NASA Langley Research Center for many years.

Hooker

Quite intelligible, you got this boy's vote.