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JET PRESSURE

JET PRESSURE

(OP)
Hi Guys,

I have following design:


how do i calculate the jet pressure for each nozzle? I have the flow from each pump is 450m^3/hour.
It has the head of 152m.
If I calculated using H=P/rho.g,
I will get P = 1.52 MPa roughly.

So, from here, should i divide the inlet pressure to number of nozzles? In my case, there are 86 nozzles.

Or, should i use this equation: Q2 = Q1 (P2/P1)^0.5

RE: JET PRESSURE

No. The pressure at each nozzle is equal to the pressure in the manifold.

No.

je suis charlie

RE: JET PRESSURE

(OP)
Thanks for your reply. You are right.

Just to share with all, there is one nozzle calculator that i found helpful for selection of the correct nozzle size.
You can click on the link below:
Link

RE: JET PRESSURE

One caveat: "the pressure at each nozzle is equal to the manifold pressure" only if the manifold pressure is constant over the length. Each nozzle will remove some mass from the system, if the sum of (say) the first 80 nozzles is greater than the inflow then pressure at the last 6 may be very low. I would want for the pump capacity to be at least twice the sum of the flow of the nozzles (using constant manifold pressure and a mass flow rate based on sonic velocity out the nozzle) and three times wouldn't be bad (nozzle wear is a real problem in these sorts of analysis).

David Simpson, PE
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist

RE: JET PRESSURE

(OP)
Yup, in addition to what David mentioned, the operational depth will also affect the performance. Correct me if i'm wrong, say pump operating pressure is 15 Bar and burial depth is 30 meter.
I have to minus 3 Bar from the operating pressure.

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