Water Nozzle Design

[KBement]

Hi everyone,

I'm currently in the process of designing a water nozzle with a set of parameters and I'm almost there but I was wondering if anyone had any materials that could further assist in design. I need to achieve 10.4 GPM minimum with only .44 psig on the inlet flowing to ambient. Best I can achieve right now is about 10 GPM. I've done all the mass flow and Bernoulli's calcs but theoretical and reality are off a bit. I'm 3D printing prototypes so not sure if the friction of the material is limiting flow. I was hoping to find more design information for nozzles like conical, parabolic, rao, astar, etc.

Anyone know of any good reference materials?

Thanks

 

[GregLocock]

I get a 1" bore should easily manage that

In sensible units, assume a perfect design

>> v=sqrt(3033/500)
v = 2.4629 m/s
>> A=.0394/60/v
A = 2.6662e-004 m^2
>> r=sqrt(A/pi)
r = 0.0092124 m


Cheers

Greg Locock


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[KBement]

Hi Greg,

Unfortunately I'm limited to my bore size to about .609". I was trying to speed up flow rate using nozzle principles

 

[GregLocock]

Ah, well that's a fairly important detail. Bernouilli says you can't do it.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[KBement]

The only way I can get there is if I pull vacuum in the nozzle to about -.35 psig. Just by nozzle design I've increased flow from 5 GPM to 10 GPM. So close I just need another lb of water in 30 seconds. Anyways, thanks for the response.

 

[WKTaylor]

KB... intriguing problem... but I am curious...

"...I'm [I've] limited to my bore size to about .609"...." ... WHY????

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[BrianE22]

Can you smooth out the nozzle bore?

 

[EdStainless]

If you are that close then every little thing like transition geometries and surface finish will be very important.
If there are any surface lines from your AM build you need to polish them out.
Solvent washing might work best, but it will change some dimensions.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[rb1957]

so using a Cd of 1 and a delta p of 0.44psi you fail
increasing the delta p to 0.79psi you just about get there
doesn't that suggest a solution ? (increase your vacuum alittle)
I expect the answer is "no".

So with a limited pressure, limited pipe diameter, there's only so much you can get in the best of all worlds (with a Cd of 1).
and this looks to be less than your 10.4 goal.

can't put a quart in a pint pot ...

another day in paradise, or is paradise one day closer ?

 

[KBement]

I was able to achieve the 10.4 GPM today with a .535” bore. Gonna see what a 550” bore will yield. There’s definitely a point of diminishing return with pressure drop on bore size with a C-D nozzle.

I’m limited to a .609” bore due to my ball valve constraints. Im doing these tests with 3D printed material so I figured I’ll gain some with a stainless nozzle, however, my mating parts may rob me of flow with the mismatch transitions.

 

[rb1957]

what Cd are you using ?

another day in paradise, or is paradise one day closer ?

 

[KBement]

CD was about .8 last time I checked. Not sure where I am now