Recirculating venturi idea

[MarkS]

Would I have any problems with this?

What happens is water is pumped through the venturi where becomes "foam". Then some of the foam is sucked back into the pump's intake and chopped up by the blade, thus increasing the amount of bubbles. This is simular the the venturi on the BakPak skimmer.

I think that this would increase the efficiency of the venturi and as a result, increase the efficiency of the skimmer.

Any thoughts?

Thanks,
Mark

[MarkS]

Anyone?

[Starmstr]

Interesting. The only problem I can think of is you are changing the density of the water by injecting air into the stream, therefore, a second venturi would need at least 2 times the force applied to reek any benefits, but don't let me dissuade you give it a shot and let me know the results.

[dbman]

Here's my take on your idea:

First - great idea!

B - By injecting foam into the intake of your pump impeller you may HUGELY reduce pumping efficiency (pump will cavitate more easily and push less water) so you should probably have a valve on your "recirculation loop" to adjust the amount of re-injection you're doing.

3 - Venturis function because of the drop in static pressure as a result of fluid velocity. I worry that with the air injected into the stream, the velocity OUT of your pump will be higher than the velocity IN... so the way you've drawn your recirculation loop, the venturi on the OUTPUT side will actually be sucking "non-foamed" water from the inlet side.

IV - you can probably work around this by using larger diameter piping on the OUTPUT side; say run 1/2" into the pump and expand it to 3/4 or 1" pipe after the outlet, even if it's only for a few inches where your recirculation tap is located. This will reduce the water velocity and increase the pressure on the output side so the "foamed" water will be more likely to be forced back to the inlet venturi. You can reduce the output piping back down to 1/2" beyond this point.


I don't know if this made any sense, please excuse the random capitalization but I had to keep all that straight in my mind as I was writing it.

[dbman]

Oh and one other thing - I believe you would have better results if rather than using the 1/2" tee and then using an adapter to reduce the branch down to fit the tubing as you showed, you just drill a hole in the pipe and epoxy a 1/4" barb into it for your recirc hose. The section of 1/2" before the adapter might play havoc with your venturi effect.

[MarkS]

This basically does the same thing, but works independently of the main pump. It might even be a good idea to add a second venturi to this pump.

Regardless, this would chop up the foam as in my original idea but without effecting the main intake pump.

[dbman]

That seems as though it should work also - looks essentially like the functional design of the turboflotor and some other systems that use a "feed pump" and a separate pump to inject air.