Equal flow Equal velocity distribution through 5 outlets 1

[bichoo]

I am trying to design a water distribution system with 5 outlets
The requirement is to have equal flow and equal velocity from all five outllets
The header is 84 inch in size
flow is 125 cfs
I am looking for 25 cfs through each outlet
What is the most optimal way to design a system like this

 

[bichoo]

The pipe length is 600 ft

 

[BigInch]

From a fluid dynamics perspective the optimum design would be like the attached.

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"Pumping systems account for nearly 20% of the world’s energy used by electric motors and 25% to 50% of the total electrical energy usage in certain industrial facilities." - DOE statistic (Note: Make that 99.99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[bichoo]

BiGInch

I am looking for 5 distribution nozzles at equal distance within a span of 600 ft

 

[BigInch]

Ya I kinda' figured it would be something like that.

You'll need to vary the header diameter, the outlet pipe diameters, use different orifice sizes, or use flow control valves. Maybe a combination of a couple of them. You lose pressure as you go out the header, so you'll need larger outlet diameters each outstep. It can also depend on what each of the pipeline system curves look like. Are the outlet pipelines all running parallel with similar profiles or do they branch off to different profiles, terminal elevations and have different lengths?



**********************
"Pumping systems account for nearly 20% of the world’s energy used by electric motors and 25% to 50% of the total electrical energy usage in certain industrial facilities." - DOE statistic (Note: Make that 99.99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[bichoo]

The outlet lines have the similar profile
What formula or equation to be used in this case
Is there a spreadsheet kind of thing that can be used to calculate the size of the reduced pipe and size of the orifices ?
I think 600 ft is a very small span to account for friction losses and other losses and backpressure from the nozzles

 

[RWF7437]

Too many questions; too few facts.

First, post a sketch of what your system would look like.
Second, define "optimum"; does that mean least first cost, maximum hydraulic efficiency, least operating cost, or what?
You can model this in EPANet or any similar pipe network program but there is no simple "formula" which will magically give you an answer.
Is this a homework problem ?

 

[katmar]

A flow of 125 cfs in an 84" pipe gives a pressure drop of less than 0.1 psi over 600 ft. If you have intermediate outlets along the way the pressure drop will be even less. The velocity in the 84" line is low enough that there will be no significant pressure recovery as the velocity decreases after each outlet.

This means that if you have a reasonable supply pressure (> 1.0 psi) you will effectively have the same pressure at each discharge point and they can all be designed to be identical. The size of the outlets will of course depend on your supply pressure, but they can all be the same size.

If there is any change of elevation then that would complicate the issue.

Katmar Software
Engineering & Risk Analysis Software

http://katmarsoftware.com

 

[BigInch]

Normally you could ignore pressure losses in such a short segment.

Just assume the same velocity everywhere (start with 10 fps to get an idea of pipe diameters) and proportion each pipe diameter based on the areas required to split flow at each tee in the proportions you want. The diameter will equal,

From A = Q/V = pi() * D^2 / 4
You know the flowrate Q that you want in each pipe segment, so solve for D

Starting with your initial flow of 125 CFS

D appx. = (4/10 * 125)^0.5 = 7.07 ft diameter = 84"
looks like your velocity constant is about 10 fps
(I think that might be a bit high, but OK we size on that basis)

Q = 100
(100 cfs * 4/10 fps)^0.5 = 6.3 ft = 76" diameter

Q = 75
run with it!

**********************
"Pumping systems account for nearly 20% of the world’s energy used by electric motors and 25% to 50% of the total electrical energy usage in certain industrial facilities." - DOE statistic (Note: Make that 99.99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[bimr]

If you install orifices with 10 psi pressure drop on each outlet, you will get equal distribution.

You can ignore the pressure drop in the header pipe as being insignificant.