Physics Help Forum Bernoulli Equation
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 Jul 29th 2016, 02:03 AM #1 Junior Member   Join Date: Jul 2016 Posts: 4 Bernoulli Equation Dear Sirs By Bernoulli equation, and a pipe reduction from 20" to 52 mm, with an initial static internal pressure of 18 Bar, and 200 cubic metrs per hour (sea water), I found a static internal pressure in the second pipe, of -18 bar! Is that possible?! I have sent my data sheet attached. Best Regards Luis Fernando
 Jul 29th 2016, 02:14 AM #2 Senior Member   Join Date: Apr 2015 Location: Somerset, England Posts: 980 Try the attachment again. Use the paperclip icon in the top toolbar.
Jul 29th 2016, 02:52 AM   #3
Junior Member

Join Date: Jul 2016
Posts: 4
Bernoulli Equation

Dear Sirs

I think now the attachment has been sent.

Best Regards

Luis Fernando
Attached Files
 Cópia de Livro1-20 in-6 in.xls (147.0 KB, 10 views)

 Jul 29th 2016, 03:45 AM #4 Senior Member   Join Date: Apr 2015 Location: Somerset, England Posts: 980 I agree your velocity calculations are close enough. Using continuity I make the inlet velocity 0.2829 m/s and the pipe velocity 26.16 m/s. But there must be some physical agent to cause this velocity, such as a pump or sloping pipe. Both these have a term in Bernoulli that you have not included. Include these and you will have a possible flow with sensible pressures.
 Jul 29th 2016, 04:11 AM #5 Junior Member   Join Date: Jul 2016 Posts: 4 Bernoulli Equation Thank you very mach, Studiot! But I did not quite understood what new terms I must includ in Bernoulli, refered to pump or any other device. Do you think it is correct to have an outlet pressure of -18 bar?! Best Regards Luis
 Jul 29th 2016, 04:59 AM #6 Senior Member   Join Date: Apr 2015 Location: Somerset, England Posts: 980 How does the water at the inlet get to be at 18 bar pressure?
 Jul 29th 2016, 06:04 AM #7 Junior Member   Join Date: Jul 2016 Posts: 4 Bernoulli Equation Dear Studiot By means of a diesel pump. It is a fire water system, feeded by sea water, as the instalation is an oil terminal. Best Regards Luis
 Aug 1st 2016, 04:26 AM #8 Junior Member     Join Date: May 2016 Location: STZGT Posts: 4 hydrodynamica The increase in the speed of a fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid's potential energy: (v^2)/2 + gz + p/d = const

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