venturi nozzle instead of sharp edged orifice

Orifice Style bench discussions
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Hans Derbe
Posts: 1
Joined: Wed Feb 16, 2011 6:18 am

venturi nozzle instead of sharp edged orifice

Post by Hans Derbe »

Hello,

does anyone here have ever used a venturi nozzle to measure flow in a flowbench? I'm thinking of a symmetrical design that could be used for intake and exhaust when used with a roots blower and vfd to reverse the flow. the extra space needed by this design an the limitation to one size wouldn't be a problem for me. Anything else to consider?
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jfholm
Posts: 1628
Joined: Fri Feb 19, 2010 7:36 pm
Location: Grantsville, Utah 45 min west of Salt Lake City

Re: venturi nozzle instead of sharp edged orifice

Post by jfholm »

I have a friend with a venturi bench. I works very well but he is a little limited due to number of motors. With a Venturi bench you can have multiple flow ranges with a single venturi just by the placement of the pressure taps on the opening big side of the venturi. I will go into it further when I get home from work.

John
jfholm
Posts: 1628
Joined: Fri Feb 19, 2010 7:36 pm
Location: Grantsville, Utah 45 min west of Salt Lake City

Re: venturi nozzle instead of sharp edged orifice

Post by jfholm »

Below are a couple of pictures that may help you visualize how a venturi bench would be set up. My friends bench only flows one direction and you can probably visualize why. To flow the exhaust ports you have to have an adapter that bolts to the exhaust port and you tip the head to set on the opening on the flow bench and suck through the exhaust port. this makes it a little tough to probe velocity in the exhaust ports.

John
venturifixed1.JPG
venturi bench.JPG
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jfholm
Posts: 1628
Joined: Fri Feb 19, 2010 7:36 pm
Location: Grantsville, Utah 45 min west of Salt Lake City

Re: venturi nozzle instead of sharp edged orifice

Post by jfholm »

Here is a venturi calculator web site if you decide to go that route
http://www.flowmeterdirectory.com/flowm ... _calc.html

John
SWR
Posts: 63
Joined: Sun Feb 28, 2010 10:00 am

Re: venturi nozzle instead of sharp edged orifice

Post by SWR »

Hmm.. 3 different venturi sizes.... swapping them by use of big Wiggins clamps either end... literally seconds to swap, much less pressure loss than a orifice bench. I think I'll test that sometime... :)
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