Can i calculate if the stream will be laminar?

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Can i calculate if the stream will be laminar?

Post  matthias on Thu Jul 01, 2010 10:26 am


its a long time ago since i've writen something hear. But maybe, i have some formulas, with which i can calculate, how good the jumper works.
With this formulas, i only calculate, how big the tube have to be and whats the biggest diameter of the nozzle.

To check, that my calculation is right, i need some information from you.

I need the follow fakts:
- The width, at that the stream isn't longer laminar
- The angle of the jumper to the floor (i think the most times something about 45°)
- The diameter of the nozzle
- The diameter of the tube

With these information, i can check, if my programm works.
If the programm works, i will post it to!

Thanks for your helf!


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Re: Can i calculate if the stream will be laminar?

Post  Ike on Thu Jul 01, 2010 7:14 pm

When you calculate the Reynolds number for the flow (Reynolds number is what you use to determine if its laminar or turbulent) you actually have to look closely at what you use for the diameter in your calculations. Is it the outer tube diameter, the outlet ring diameter, or the diameter of the individual straws?

When you do the calculations you'll find the diameter of the straws is the sole reason for the laminar flow. The diameter of the outer pipe and the diameter of the outlet ring is actually working against us! By a lot! So what's happening is that we are fighting to get the laminar output of the straws out into the water arch before the outer pipe and nozzle ring can reduce the flow back to turbulence.

I did an excel spreadsheet a while back to try and figure things out before I started building my own laminar nozzle. Below is a screen shot of it. If anyone wants a copy of the spreadsheet so they can put in their own diameters and pump output send me a personal message here on the forum.

The spreadsheet looks at the reynolds number for the outer pipe, the output ring, and the individual straws and compares them.

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